Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r271099: revert r269814: blkfront: add support for unmapped IO

Current busdma code for unmapped bios will not properly align the
segment size, causing corruption on blkfront devices. Revert the commit
until busdma code is fixed.

Reported by: mav
Approved by: re

MFC r269814:

blkfront: add support for unmapped IO

Sponsored by: Citrix Systems R&D
Tested by: robak
PR: 191173

MFC r257334, r257336, r257337, r257338, r257341, r257342, r257343, r257370,
r257368, r257416

Hints-only devices should return BUS_PROBE_NOWILDCARD from their probe
methods.

MFC r261916:

In sys/dev/xen/console/console.c, #if 0 an unused static function.

MFC r258622: dtrace sdt: remove the ugly sname parameter of SDT_PROBE_DEFINE

Merge r256868,257276-257277,257515,257913 from head. These are fixes
required to make Xen buтldable w/o INET.

Sponsored by: Nginx, Inc.

MFC 258178:

Improve robustness of the Xen balloon driver.

sys/dev/xen/balloon/balloon.c:
Remove unused and commented out code.

Fix deadlock caused by performing a sleepable malloc
while holding the balloon mutex.

Perform proper accounting of the memory used by the domain.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs
Approved by: gibbs (mentor)
Approved by: re (gjb)

MFC 257876:

On XenServer the "halt" message is used instead of "poweroff", which
makes FreeBSD halt but not poweroff (as expected when issuing a
shutdown from the VM manager). Fix this by using the same handler
for both "halt" and "poweroff".

NB: The "halt" signal seems to be used on XenServer only. The OSS
Xen toolstack (xl) uses "poweroff" instead.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs
Approved by: gibbs (mentor)
Approved by: re (gjb)

MFC: r256425

Centralize the detection logic for the Hyper-V hypervisor.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs, grehan
Approved by: re (gjb)

sys/sys/systm.h:
* Add a new VM_GUEST type, VM_GUEST_HV (HyperV guest).

sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c:
sys/dev/hyperv/vmbus/hv_hv.c:
sys/dev/hyperv/stordisengage/hv_ata_pci_disengage.c:
* Set vm_guest to VM_GUEST_HV and use that on other HyperV related
devices instead of cloning the cpuid hypervisor check.
* Cleanup the vmbus_identify function.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Initialize a variable in sys/dev/xen/control/control.c, to silence a gcc
warning.

Approved by: re (gjb)
MFC after: 3 days

Formalize the concept of virtual CPU ids by adding a per-cpu vcpu_id
field. Perform vcpu enumeration for Xen PV and HVM environments
and convert all Xen drivers to use vcpu_id instead of a hard coded
assumption of the mapping algorithm (acpi or apic ID) in use.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs
Approved by: re (blanket Xen)

amd64/include/pcpu.h:
i386/include/pcpu.h:
Add vcpu_id to the amd64 and i386 pcpu structures.

dev/xen/timer/timer.c
x86/xen/xen_intr.c
Use new vcpu_id instead of assuming acpi_id == vcpu_id.

i386/xen/mp_machdep.c:
i386/xen/mptable.c
x86/xen/hvm.c:
Perform Xen HVM and Xen full PV vcpu_id mapping.

x86/xen/hvm.c:
x86/acpica/madt.c
Change SYSINIT ordering of acpi CPU enumeration so that it
is guaranteed to be available at the time of Xen HVM vcpu
id mapping.

Add support for suspend/resume/migration operations when running as a
Xen PVHVM guest.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs
Approved by: re (blanket Xen)
MFC after: 2 weeks

sys/amd64/amd64/mp_machdep.c:
sys/i386/i386/mp_machdep.c:
- Make sure that are no MMU related IPIs pending on migration.
- Reset pending IPI_BITMAP on resume.
- Init vcpu_info on resume.

sys/amd64/include/intr_machdep.h:
sys/i386/include/intr_machdep.h:
sys/x86/acpica/acpi_wakeup.c:
sys/x86/x86/intr_machdep.c:
sys/x86/isa/atpic.c:
sys/x86/x86/io_apic.c:
sys/x86/x86/local_apic.c:
- Add a "suspend_cancelled" parameter to pic_resume(). For the
Xen PIC, restoration of interrupt services differs between
the aborted suspend and normal resume cases, so we must provide
this information.

sys/dev/acpica/acpi_timer.c:
sys/dev/xen/timer/timer.c:
sys/timetc.h:
- Don't swap out "suspend safe" timers across a suspend/resume
cycle. This includes the Xen PV and ACPI timers.

sys/dev/xen/control/control.c:
- Perform proper suspend/resume process for PVHVM:
- Suspend all APs before going into suspension, this allows us
to reset the vcpu_info on resume for each AP.
- Reset shared info page and callback on resume.

sys/dev/xen/timer/timer.c:
- Implement suspend/resume support for the PV timer. Since FreeBSD
doesn't perform a per-cpu resume of the timer, we need to call
smp_rendezvous in order to correctly resume the timer on each CPU.

sys/dev/xen/xenpci/xenpci.c:
- Don't reset the PCI interrupt on each suspend/resume.

sys/kern/subr_smp.c:
- When suspending a PVHVM domain make sure there are no MMU IPIs
in-flight, or we will get a lockup on resume due to the fact that
pending event channels are not carried over on migration.
- Implement a generic version of restart_cpus that can be used by
suspended and stopped cpus.

sys/x86/xen/hvm.c:
- Implement resume support for the hypercall page and shared info.
- Clear vcpu_info so it can be reset by APs when resuming from
suspension.

sys/dev/xen/xenpci/xenpci.c:
sys/x86/xen/hvm.c:
sys/x86/xen/xen_intr.c:
- Support UP kernel configurations.

sys/x86/xen/xen_intr.c:
- Properly rebind per-cpus VIRQs and IPIs on resume.

Correct blkback handling of the BLKIF_OP_FLUSH_DISKCACHE opcode.

Properly round-trip the "operation code" for client requests.

sys/dev/xen/blkback/blkback.c:
In xbb_dispatch_dev() when processing a flush request,
correctly set bio->bio_caller1 to the request list (not
bare request) for the operation, as is expected by the
completion handler xbb_bio_done().

In xbb_get_resources(), initialize "operation" in the
driver's internal request object from the client's "ring
request", so it is correct when used to populate the reply
when this operation completes.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs

sys/dev/xen/blkback/blkback.c:
Initialize the request id for requests in xbb_get_resources()
instead of its previous location in xbb_dispatch_io(). This
guarantees that all request types (e.g. BLKIF_OP_FLUSH_DISKCACHE)
have the front-end specified id recorded.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D

If reading a virtual-device value fails, attempt to read a virtual-device-ext
value. Some hosts do not publish "extended" disk IDs via virtual-device in
an attempt to avoid confusing old blkfront drivers, and without this change
we failed to attach such disks.

In particular, this commit allows all 24 ephemeral disks on EC2 hs1.8xlarge
instances to be used, instead of only the first 15.

MFC after: 3 days

Introduce a new, HVM compatible, paravirtualized timer driver for Xen.
Use this new driver for both PV and HVM instances.

This driver requires a Xen hypervisor that supports vector callbacks,
VCPUOP hypercalls, and reports that it has a "safe PV clock".

New timer driver:
Submitted by: will
Sponsored by: Spectra Logic Corporation

PV port to new driver, and bug fixes:
Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D

sys/dev/xen/timer/timer.c:
- Register a PV timer device driver which (currently)
implements device_{identify,probe,attach} and stubs
device_detach. The detach routine requires functionality
not provided by timecounters(4). The suspend and resume
routines need additional work (due to Xen requiring that
the hypercalls be executed on the target VCPU), and aren't
needed for our purposes.

- Make sure there can only be one device instance of this
driver, and that it only registers one eventtimers(4) and
one timecounters(4) device interface. Make both interfaces
use PCPU data as needed.

- Match, with a few style cleanups & API differences, the
Xen versions of the "fetch time" functions.

- Document the magic scale_delta() better for the i386 version.

- When registering the event timer, bind a separate event
channel for the timer VIRQ to the device's event timer
interrupt handler for each active VCPU. Describe each
interrupt as "xen_et:c%d", so they can be identified per
CPU in "vmstat -i" or "show intrcnt" in KDB.

- When scheduling a timer into the hypervisor, try up to
60 times if the hypervisor rejects the time as being in
the past. In the common case, this retry shouldn't happen,
and if it does, it should only happen once. This is
because the event timer advertises a minimum period of
100usec, which is only less than the usual hypercall round
trip time about 1 out of every 100 tries. (Unlike other
similar drivers, this one actually checks whether the
hypervisor accepted the singleshot timer set hypercall.)

- Implement a RTC PV clock based on the hypervisor wallclock.

sys/conf/files:
- Add dev/xen/timer/timer.c if the kernel configuration
includes either the XEN or XENHVM options.

sys/conf/files.i386:
sys/i386/include/xen/xen_clock_util.h:
sys/i386/xen/clock.c:
sys/i386/xen/xen_clock_util.c:
sys/i386/xen/mp_machdep.c:
sys/i386/xen/xen_rtc.c:
- Remove previous PV timer used in i386 XEN PV kernels, the
new timer introduced in this change is used instead (so
we share the same code between PVHVM and PV).

MFC after: 2 weeks

Implement vector callback for PVHVM and unify event channel implementations

Re-structure Xen HVM support so that:
- Xen is detected and hypercalls can be performed very
early in system startup.
- Xen interrupt services are implemented using FreeBSD's native
interrupt delivery infrastructure.
- the Xen interrupt service implementation is shared between PV
and HVM guests.
- Xen interrupt handlers can optionally use a filter handler
in order to avoid the overhead of dispatch to an interrupt
thread.
- interrupt load can be distributed among all available CPUs.
- the overhead of accessing the emulated local and I/O apics
on HVM is removed for event channel port events.
- a similar optimization can eventually, and fairly easily,
be used to optimize MSI.

Early Xen detection, HVM refactoring, PVHVM interrupt infrastructure,
and misc Xen cleanups:

Sponsored by: Spectra Logic Corporation

Unification of PV & HVM interrupt infrastructure, bug fixes,
and misc Xen cleanups:

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D

sys/x86/x86/local_apic.c:
sys/amd64/include/apicvar.h:
sys/i386/include/apicvar.h:
sys/amd64/amd64/apic_vector.S:
sys/i386/i386/apic_vector.s:
sys/amd64/amd64/machdep.c:
sys/i386/i386/machdep.c:
sys/i386/xen/exception.s:
sys/x86/include/segments.h:
Reserve IDT vector 0x93 for the Xen event channel upcall
interrupt handler. On Hypervisors that support the direct
vector callback feature, we can request that this vector be
called directly by an injected HVM interrupt event, instead
of a simulated PCI interrupt on the Xen platform PCI device.
This avoids all of the overhead of dealing with the emulated
I/O APIC and local APIC. It also means that the Hypervisor
can inject these events on any CPU, allowing upcalls for
different ports to be handled in parallel.

sys/amd64/amd64/mp_machdep.c:
sys/i386/i386/mp_machdep.c:
Map Xen per-vcpu area during AP startup.

sys/amd64/include/intr_machdep.h:
sys/i386/include/intr_machdep.h:
Increase the FreeBSD IRQ vector table to include space
for event channel interrupt sources.

sys/amd64/include/pcpu.h:
sys/i386/include/pcpu.h:
Remove Xen HVM per-cpu variable data. These fields are now
allocated via the dynamic per-cpu scheme. See xen_intr.c
for details.

sys/amd64/include/xen/hypercall.h:
sys/dev/xen/blkback/blkback.c:
sys/i386/include/xen/xenvar.h:
sys/i386/xen/clock.c:
sys/i386/xen/xen_machdep.c:
sys/xen/gnttab.c:
Prefer FreeBSD primatives to Linux ones in Xen support code.

sys/amd64/include/xen/xen-os.h:
sys/i386/include/xen/xen-os.h:
sys/xen/xen-os.h:
sys/dev/xen/balloon/balloon.c:
sys/dev/xen/blkback/blkback.c:
sys/dev/xen/blkfront/blkfront.c:
sys/dev/xen/console/xencons_ring.c:
sys/dev/xen/control/control.c:
sys/dev/xen/netback/netback.c:
sys/dev/xen/netfront/netfront.c:
sys/dev/xen/xenpci/xenpci.c:
sys/i386/i386/machdep.c:
sys/i386/include/pmap.h:
sys/i386/include/xen/xenfunc.h:
sys/i386/isa/npx.c:
sys/i386/xen/clock.c:
sys/i386/xen/mp_machdep.c:
sys/i386/xen/mptable.c:
sys/i386/xen/xen_clock_util.c:
sys/i386/xen/xen_machdep.c:
sys/i386/xen/xen_rtc.c:
sys/xen/evtchn/evtchn_dev.c:
sys/xen/features.c:
sys/xen/gnttab.c:
sys/xen/gnttab.h:
sys/xen/hvm.h:
sys/xen/xenbus/xenbus.c:
sys/xen/xenbus/xenbus_if.m:
sys/xen/xenbus/xenbusb_front.c:
sys/xen/xenbus/xenbusvar.h:
sys/xen/xenstore/xenstore.c:
sys/xen/xenstore/xenstore_dev.c:
sys/xen/xenstore/xenstorevar.h:
Pull common Xen OS support functions/settings into xen/xen-os.h.

sys/amd64/include/xen/xen-os.h:
sys/i386/include/xen/xen-os.h:
sys/xen/xen-os.h:
Remove constants, macros, and functions unused in FreeBSD's Xen
support.

sys/xen/xen-os.h:
sys/i386/xen/xen_machdep.c:
sys/x86/xen/hvm.c:
Introduce new functions xen_domain(), xen_pv_domain(), and
xen_hvm_domain(). These are used in favor of #ifdefs so that
FreeBSD can dynamically detect and adapt to the presence of
a hypervisor. The goal is to have an HVM optimized GENERIC,
but more is necessary before this is possible.

sys/amd64/amd64/machdep.c:
sys/dev/xen/xenpci/xenpcivar.h:
sys/dev/xen/xenpci/xenpci.c:
sys/x86/xen/hvm.c:
sys/sys/kernel.h:
Refactor magic ioport, Hypercall table and Hypervisor shared
information page setup, and move it to a dedicated HVM support
module.

HVM mode initialization is now triggered during the
SI_SUB_HYPERVISOR phase of system startup. This currently
occurs just after the kernel VM is fully setup which is
just enough infrastructure to allow the hypercall table
and shared info page to be properly mapped.

sys/xen/hvm.h:
sys/x86/xen/hvm.c:
Add definitions and a method for configuring Hypervisor event
delievery via a direct vector callback.

sys/amd64/include/xen/xen-os.h:
sys/x86/xen/hvm.c:

sys/conf/files:
sys/conf/files.amd64:
sys/conf/files.i386:
Adjust kernel build to reflect the refactoring of early
Xen startup code and Xen interrupt services.

sys/dev/xen/blkback/blkback.c:
sys/dev/xen/blkfront/blkfront.c:
sys/dev/xen/blkfront/block.h:
sys/dev/xen/control/control.c:
sys/dev/xen/evtchn/evtchn_dev.c:
sys/dev/xen/netback/netback.c:
sys/dev/xen/netfront/netfront.c:
sys/xen/xenstore/xenstore.c:
sys/xen/evtchn/evtchn_dev.c:
sys/dev/xen/console/console.c:
sys/dev/xen/console/xencons_ring.c
Adjust drivers to use new xen_intr_*() API.

sys/dev/xen/blkback/blkback.c:
Since blkback defers all event handling to a taskqueue,
convert this task queue to a "fast" taskqueue, and schedule
it via an interrupt filter. This avoids an unnecessary
ithread context switch.

sys/xen/xenstore/xenstore.c:
The xenstore driver is MPSAFE. Indicate as much when
registering its interrupt handler.

sys/xen/xenbus/xenbus.c:
sys/xen/xenbus/xenbusvar.h:
Remove unused event channel APIs.

sys/xen/evtchn.h:
Remove all kernel Xen interrupt service API definitions
from this file. It is now only used for structure and
ioctl definitions related to the event channel userland
device driver.

Update the definitions in this file to match those from
NetBSD. Implementing this interface will be necessary for
Dom0 support.

sys/xen/evtchn/evtchnvar.h:
Add a header file for implemenation internal APIs related
to managing event channels event delivery. This is used
to allow, for example, the event channel userland device
driver to access low-level routines that typical kernel
consumers of event channel services should never access.

sys/xen/interface/event_channel.h:
sys/xen/xen_intr.h:
Standardize on the evtchn_port_t type for referring to
an event channel port id. In order to prevent low-level
event channel APIs from leaking to kernel consumers who
should not have access to this data, the type is defined
twice: Once in the Xen provided event_channel.h, and again
in xen/xen_intr.h. The double declaration is protected by
__XEN_EVTCHN_PORT_DEFINED__ to ensure it is never declared
twice within a given compilation unit.

sys/xen/xen_intr.h:
sys/xen/evtchn/evtchn.c:
sys/x86/xen/xen_intr.c:
sys/dev/xen/xenpci/evtchn.c:
sys/dev/xen/xenpci/xenpcivar.h:
New implementation of Xen interrupt services. This is
similar in many respects to the i386 PV implementation with
the exception that events for bound to event channel ports
(i.e. not IPI, virtual IRQ, or physical IRQ) are further
optimized to avoid mask/unmask operations that aren't
necessary for these edge triggered events.

Stubs exist for supporting physical IRQ binding, but will
need additional work before this implementation can be
fully shared between PV and HVM.

sys/amd64/amd64/mp_machdep.c:
sys/i386/i386/mp_machdep.c:
sys/i386/xen/mp_machdep.c
sys/x86/xen/hvm.c:
Add support for placing vcpu_info into an arbritary memory
page instead of using HYPERVISOR_shared_info->vcpu_info.
This allows the creation of domains with more than 32 vcpus.

sys/i386/i386/machdep.c:
sys/i386/xen/clock.c:
sys/i386/xen/xen_machdep.c:
sys/i386/xen/exception.s:
Add support for new event channle implementation.

Remove duplicate dev.xbd.*.max_requests sysctl added in r252260.

Approved by: gibbs

Fix mbuf debugging printf()'s after the recent mbuf header changes.

Replace kernel virtual address space allocation with vmem. This provides
transparent layering and better fragmentation.

- Normalize functions that allocate memory to use kmem_*
- Those that allocate address space are named kva_*
- Those that operate on maps are named kmap_*
- Implement recursive allocation handling for kmem_arena in vmem.

Reviewed by: alc
Tested by: pho
Sponsored by: EMC / Isilon Storage Division

In the Xen block front driver, take advantage of backends that
support cache flush and write barrier commands.

sys/dev/xen/blkfront/block.h:
Add per-command flag that specifies that the I/O queue must
be frozen after this command is dispatched. This is used
to implement "single-stepping".

Remove the unused per-command flag that indicates a polled
command.

Add block device instance flags to record backend features.

Add a block device instance flag to indicate the I/O queue
is frozen until all outstanding I/O completes.

Enhance the queue API to allow the number of elements in a
queue to be interrogated.

Prefer "inline" to "__inline".

sys/dev/xen/blkfront/blkfront.c:
Formalize queue freeze semantics by adding methods for both
global and command-associated queue freezing.

Provide mechanism to freeze the I/O queue until all outstanding
I/O completes. Use this to implement barrier semantics
(BIO_ORDERED) when the backend does not support
BLKIF_OP_WRITE_BARRIER commands.

Implement BIO_FLUSH as either a BLKIF_OP_FLUSH_DISKCACHE
command or a 0 byte write barrier. Currently, all publicly
available backends perform a diskcache flush when processing
barrier commands, and this frontend behavior matches what
is done in Linux.

Simplify code by using new queue length API.

Report backend features during device attach and via sysctl.

Submitted by: Roger Pau Monné
Submitted by: gibbs (Merge with new driver queue API, sysctl support)

sys/dev/xen/blkfront/blkfront.c:
In xbd_thaw(), fix inverted logic to verify the queue is frozen
before attempting a thaw.

MFC after: 1 week

Properly track the different reasons new I/O is temporarily disabled, and
only re-enable I/O when all reasons have cleared.

sys/dev/xen/blkfront/block.h:
In the block front driver softc, replace the boolean
XBDF_FROZEN flag with a count of commands and driver global
issues that freeze the I/O queue. So long xbd_qfrozen_cnt
is non-zero, I/O is halted.

Add flags to xbd_flags for tracking grant table entry and
free command resource shortages. Each of these classes can
increment xbd_qfrozen_cnt at most once.

Add a command flag (XBDCF_ASYNC_MAPPING) that is set whenever
the initial mapping attempt of a command fails with EINPROGRESS.

sys/dev/xen/blkfront/blkfront.c:
In xbd_queue_cb(), use new XBDCF_ASYNC_MAPPING flag to definitively
know if an async bus dmamap load has occurred.

Add xbd_freeze() and xbd_thaw() helper methods for managing
xbd_qfrozen_cnt and use them to implement all queue freezing logic.

Add missing "thaw" to restart I/O processing once grant references
become available.

Sponsored by: Spectra Logic Corporation

Improve debugger visibility into queuing functions by removing the macro
scheme for defining inline command queuing functions.

Prefer enums to #defines.

sys/dev/xen/blkfront/block.h
Replace inline function generation performed by the
XBDQ_COMMAND_QUEUE() macro with single instances of each
inline function (init, enqueue, dequeue, remove). This was
made possible by using queue indexes instead of bit flags
in the command structure, and passing the index enum as
an argument to the functions.

Improve panic/assert messages in the queue functions.

Combine queue data and stats into a single data structure
and declare an array of them instead of each queue individually.

Convert command flags, softc state, and softc flags to enums.

sys/dev/xen/blkfront/blkfront.c
Mechanical adjustments for new queue api.

Sponsored by: Spectra Logic Corporation
MFC after: 1 week

sys/dev/xen/netfront/netfront.c:
In netif_free(), call ifmedia_removeall() after ether_ifdetach()
so that bpf listeners are detached, any link state processing
is completed, and there is no chance for external reference to media
information.

Suggested by: yongari
MFC after: 1 week

Specify a maximum TSO length limiting the segment chain to what the
Xen host side can handle after defragmentation.

This prevents the driver from throwing away too long TSO chains and
improves the performance on Amazon AWS instances with 10GigE virtual
interfaces to the normally expected throughput.

Submitted by: cperciva (earlier version)
Reviewed by: cperciva
Tested by: cperciva
MFC after: 1 week

sys/dev/xen/blkfront/blkfront.c:
Remove dead code.

Sponsored by: Spectra Logic Corporation
MFC after: 1 week

sys/dev/xen/blkfront/blkfront.c:
Remove local, and incorrect, definition for the value of an invalid
grant reference.

Extract ring cleanup code into xbd_free_ring() function for
symetry with xbd_alloc_ring(). This process also eliminated
an initialized but unused variable.

Sponsored by: Spectra Logic Corporation
MFC after: 1 week

Style changes. No intended functional changes.

o rename flush_requests => xbd_flush_requests
o rename xbd_setup_ring => xbd_alloc_ring

Sponsored by: Spectra Logic Corporation
MFC after: 1 week

Style cleanups. No intended functional changes.

o Group functions by by their functionality.
o Remove superfluous declarations.
o Remove more unused (#ifdef'd out) code.

Sponsored by: Spectra Logic Corporation

Style cleanups. No intended functional changes.

o This driver is the "xbd" driver, not the "blkfront", "blkif", "xbf", or
"xb" driver. Use the "xbd_" naming conventions for all functions,
structures, and constants.
o The prevailing convention for structure fields in this driver is to
prefix them with an abreviation of the structure type. Update
"recently added" fields to match this style.
o Remove unused data structures.
o Remove superfluous casts.
o Make a pass over the whole driver and bring it closer to
style(9) conformance.

Sponsored by: Spectra Logic Corporation
MFC after: 1 week

Make netif_free() safe to call on a partially initialized softc.

Sponsored by: Spectra Logic Corporation
MFC after: 1 week

Apply the ad* => ada* IDE device name transition to the Xen block
front driver.

Submitted by: Bei Guan <gbtju85@gmail.com>
Reviewed by: gibbs
MFC after: 1 week

Correct panic on detach of Xen PV network interfaces.

dev/xen/netfront:
In netif_free(), properly stop the interface and drain any pending
timers prior to disconnecting from the backend device.

Remove all media and detach our interface object from the system
prior to deleting it.

PR: kern/176471
Submitted by: Roger Pau Monne <roger.pau@citrix.com>
Reviewed by: gibbs
MFC after: 1 week

- Correct spelling in comments

Submitted by: Christoph Mallon <christoph.mallon@gmx.de> (via private mail)

- Correct mispellings of the word necessary

Submitted by: Christoph Mallon <christoph.mallon@gmx.de> (via private mail)

Use DEVMETHOD_END macro defined in sys/bus.h instead of {0, 0} sentinel on device_method_t arrays

Reviewed by: cognet
Approved by: cognet

Remove files not connected to the build. It's confusing enough that
we still have two not quite the same evtchn.c left over.

MFC after: 3 day

- Replace partially incorrect function names in panic(9) strings with
__func__ and add some missing ones.
- Remove a stale comment.
- Remove unused NUM_ELEMENTS macro.
- Remove extra empty lines.
- Use DEVMETHOD_END.
- Use NULL rather than 0 for pointers.

MFC after: 3 days

- Fix !SMP build.
- Replace incorrect function names in printf(9) strings with __func__.
- Make xctrl_shutdown_reasons table const.
- Use nitems() rather than rolling an own version.
- Use DEVMETHOD_END.
- Use NULL rather than 0 for pointers.

MFC after: 3 days

Mechanically substitute flags from historic mbuf allocator with
malloc(9) flags in sys/dev.

Redo r242889, now using the method from projects/amd64_xen_pv r240747.

Reminded by: kib
MFC after: 3 days

Fix a typo.

Change the XNB_ASSERT from a statement expression to do-while(0) as its
result is never used.

Remove the support for using non-mpsafe filesystem modules.

In particular, do not lock Giant conditionally when calling into the
filesystem module, remove the VFS_LOCK_GIANT() and related
macros. Stop handling buffers belonging to non-mpsafe filesystems.

The VFS_VERSION is bumped to indicate the interface change which does
not result in the interface signatures changes.

Conducted and reviewed by: attilio
Tested by: pho

s/ is is / is /g
s/ a a / a /g

Approved by: cperciva
MFC after: 3 days

Fix a bug which causes a panic in daopen(). The panic is caused by
a da(4) instance going away while GEOM is still probing it.

In this case, the GEOM disk class instance has been created by
disk_create(), and the taste of the disk is queued in the GEOM
event queue.

While that event is queued, the da(4) instance goes away. When the
open call comes into the da(4) driver, it dereferences the freed
(but non-NULL) peripheral pointer provided by GEOM, which results
in a panic.

The solution is to add a callback to the GEOM disk code that is
called when all of its resources are cleaned up. This is
implemented inside GEOM by adding an optional callback that is
called when all consumers have detached from a provider, and the
provider is about to be deleted.

scsi_cd.c,
scsi_da.c: In the register routine for the cd(4) and da(4)
routines, acquire a reference to the CAM peripheral
instance just before we call disk_create().

Use the new GEOM disk d_gone() callback to register
a callback (dadiskgonecb()/cddiskgonecb()) that
decrements the peripheral reference count once GEOM
has finished cleaning up its resources.

In the cd(4) driver, clean up open and close
behavior slightly. GEOM makes sure we only get one
open() and one close call, so there is no need to
set an open flag and decrement the reference count
if we are not the first open.

In the cd(4) driver, use cam_periph_release_locked()
in a couple of error scenarios to avoid extra mutex
calls.

geom.h: Add a new, optional, providergone callback that
is called when a provider is about to be deleted.

geom_disk.h: Add a new d_gone() callback to the GEOM disk
interface.

Bump the DISK_VERSION to version 2. This probably
should have been done after a couple of previous
changes, especially the addition of the d_getattr()
callback.

geom_disk.c: Add a providergone callback for the disk class,
g_disk_providergone(), that calls the user's
d_gone() callback if it exists.

Bump the DISK_VERSION to 2.

geom_subr.c: In g_destroy_provider(), call the providergone
callback if it has been provided.

In g_new_geomf(), propagate the class's
providergone callback to the new geom instance.

blkfront.c: Callers of disk_create() are supposed to pass in
DISK_VERSION, not an explicit disk API version
number. Update the blkfront driver to do that.

disk.9: Update the disk(9) man page to include information
on the new d_gone() callback, as well as the
previously added d_getattr() callback, d_descr
field, and HBA PCI ID fields.

MFC after: 5 days

Allow booting XENHVM kernel without Xen hypervisor.

MFC after: 3 days

Free ballooned pages with the corresponding malloc type.

MFC after: 1 week

Correct failure to attach the PV block front device on Citrix
XenServer configurations that advertise the multi-page ring extension,
but only allow a single page of ring space.

sys/dev/xen/blkfront/blkfront.c:
If only one page of ring space is being used, do not publish
in the XenStore the number of pages in use (1), via either
of the supported multi-page ring extension schemes.

Single page operation is the same with or without the
ring-page extension being negotiated. Relying on the
legacy behavior avoids an incompatible difference in how
the two ring-page extension schemes that are out in the
wild, deal with the base case of a single page. The
Amazon/Red Hat drivers use the same XenStore variable as
if the extension was not negotiated. The Citrix drivers
assume the new ring reference XenStore variables will be
available

Reported by: Oliver Schonefeld <schonefeld@ids-mannheim.de>
MFC after: 3 days

Final pass at having devices use their bus parent for dma tags. The
remaining drivers that haven't been converted have various problems or
complexities that will be dealt with later. This list includes:

hptrr, hptmv, hpt27xx - device aggregation across multiple parents
drm - want to talk to the maintainer first
tsec, sec - Openfirmware devices, not sure if changes are warranted
fatm - Done except for unused testing code
usb - want to talk to the maintainer first
ce, cp, ctau, cx - Significant driver changes needed to convey parent info

There are also devices tucked into architecture subtrees that I'll leave
for the respective maintainers to deal with.

Fix regression in the handling of blkback close events for
devices that are unplugged via QEMU.

sys/dev/xen/blkback/blkback.c:
Toolstack initiated closures change the frontend's state
to Closing. The backend must change to Closing as well,
even if we can't actually close yet, in order for the
frontend to notice and start the closing process.

MFC after: 3 days

Fix a bug in the calculation of the maximum I/O request size.
The previous code did not limit the I/O request size based on
the maximum number of segments supported by the back-end. In
current practice, since the only back-end supporting chained
requests is the FreeBSD implementation, this limit was never
exceeded.

sys/dev/xen/blkfront/block.h:
Add two macros, XBF_SEGS_TO_SIZE() and XBF_SIZE_TO_SEGS(),
to centralize the logic of reserving a segment to deal with
non-page-aligned I/Os.

sys/dev/xen/blkfront/blkfront.c:
o When negotiating transfer parameters, limit the
max_request_size we use and publish, if it is greater
than the maximum, unaligned, I/O we can support with
the number of segments advertised by the backend.
o Don't unilaterally reduce the I/O size published to
the disk layer by a single page. max_request_size
is already properly limited in the transfer parameter
negotiation code.
o Fix typos in printf strings:
"max_requests_segments" -> "max_request_segments"
"specificed" -> "specified"

MFC after: 1 day

Fix typo in a printf string: "specificed" -> "specified".

MFC after: 1 day

Enhance documentation, improve interoperability, and fix defects in
FreeBSD's front and back Xen blkif interface drivers.

sys/dev/xen/blkfront/block.h:
sys/dev/xen/blkfront/blkfront.c:
sys/dev/xen/blkback/blkback.c:
Replace FreeBSD specific multi-page ring impelementation with
support for both the Citrix and Amazon/RedHat versions of this
extension.

sys/dev/xen/blkfront/blkfront.c:
o Add a per-instance sysctl tree that exposes all negotiated
transport parameters (ring pages, max number of requests,
max request size, max number of segments).
o In blkfront_vdevice_to_unit() add a missing return statement
so that we properly identify the unit number for high numbered
xvd devices.

sys/dev/xen/blkback/blkback.c:
o Add static dtrace probes for several events in this driver.
o Defer connection shutdown processing until the front-end
enters the closed state. This avoids prematurely tearing
down the connection when buggy front-ends transition to the
closing state, even though the device is open and they
veto the close request from the tool stack.
o Add nodes for maximum request size and the number of active
ring pages to the exising, per-instance, sysctl tree.
o Miscelaneous style cleanup.

sys/xen/interface/io/blkif.h:
o Add extensive documentation of the XenStore nodes used to
implement the blkif interface.
o Document the startup sequence between a front and back driver.
o Add structures and documenatation for the "discard" feature
(AKA Trim).
o Cleanup some definitions related to FreeBSD's request
number/size/segment-limit extension.

sys/dev/xen/blkfront/blkfront.c:
sys/dev/xen/blkback/blkback.c:
sys/xen/xenbus/xenbusvar.h:
Add the convenience function xenbus_get_otherend_state() and
use it to simplify some logic in both block-front and block-back.

MFC after: 1 day

Fix the netback driver build for i386.

netback.c: Add missing VM includes.

xen/xenvar.h,
xen/xenpmap.h: Move some XENHVM macros from <machine/xen/xenpmap.h> to
<machine/xen/xenvar.h> on i386 to match the amd64 headers.

conf/files: Add netback to the build.

Submitted by: jhb
MFC after: 3 days

Xen netback driver rewrite.

share/man/man4/Makefile,
share/man/man4/xnb.4,
sys/dev/xen/netback/netback.c,
sys/dev/xen/netback/netback_unit_tests.c:

Rewrote the netback driver for xen to attach properly via newbus
and work properly in both HVM and PVM mode (only HVM is tested).
Works with the in-tree FreeBSD netfront driver or the Windows
netfront driver from SuSE. Has not been extensively tested with
a Linux netfront driver. Does not implement LRO, TSO, or
polling. Includes unit tests that may be run through sysctl
after compiling with XNB_DEBUG defined.

sys/dev/xen/blkback/blkback.c,
sys/xen/interface/io/netif.h:

Comment elaboration.

sys/kern/uipc_mbuf.c:

Fix page fault in kernel mode when calling m_print() on a
null mbuf. Since m_print() is only used for debugging, there
are no performance concerns for extra error checking code.

sys/kern/subr_scanf.c:

Add the "hh" and "ll" width specifiers from C99 to scanf().
A few callers were already using "ll" even though scanf()
was handling it as "l".

Submitted by: Alan Somers <alans@spectralogic.com>
Submitted by: John Suykerbuyk <johns@spectralogic.com>
Sponsored by: Spectra Logic
MFC after: 1 week
Reviewed by: ken

Make XENHVM work on i386. The __ffs() function counts bits starting from
zero, unlike ffs(3), which starts counting from 1.

ether_ifattach() sets if_mtu to ETHERMTU, don't bother set it again

Reviewed by: yongari

kern cons: introduce infrastructure for console grabbing by kernel

At the moment grab and ungrab methods of all console drivers are no-ops.

Current intended meaning of the calls is that the kernel takes control of
console input. In the future the semantics may be extended to mean that
the calling thread takes full ownership of the console (e.g. console
output from other threads could be suspended).

Inspired by: bde
MFC after: 2 months

Replace `inline static' by `static inline'.

If I interpret the C standard correctly, the storage specifier should be
placed before the inline keyword. While at it, replace __inline by
inline in the files affected.

- There's no need to overwrite the default device method with the default
one. Interestingly, these are actually the default for quite some time
(bus_generic_driver_added(9) since r52045 and bus_generic_print_child(9)
since r52045) but even recently added device drivers do this unnecessarily.
Discussed with: jhb, marcel
- While at it, use DEVMETHOD_END.
Discussed with: jhb
- Also while at it, use __FBSDID.

Mark all SYSCTL_NODEs static that have no corresponding SYSCTL_DECLs.

The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.

Mark MALLOC_DEFINEs static that have no corresponding MALLOC_DECLAREs.

This means that their use is restricted to a single C file.

Eliminate vestiges of page coloring in VM_ALLOC_NOOBJ calls to
vm_page_alloc(). While I'm here, for the sake of consistency, always
specify the allocation class, such as VM_ALLOC_NORMAL, as the first of
the flags.

Update netfront so that it queries and honors published
back-end features.

sys/dev/xen/netfront/netfront.c:
o Add xn_query_features() which reads the XenStore and
records the TSO, LRO, and chained ring-request support
of the backend.
o Rename xn_configure_lro() to xn_configure_features() and
use this routine to manage the setup of TSO, LRO, and
checksum offload.
o In create_netdev(), initialize if_capabilities and
if_hwassist to the capabilities found on all backends.
Delegate configuration of if_capenable and the TSO flag
if if_hwassist to xn_configure_features().

Reported by: Hugo Silva (fix inspired by patch provided)
Approved by: re
MFC after: 1 week

Modify the netfront driver so it can successfully attach to
PV devices with the ioemu attribute set.

sys/dev/xen/netfront/netfront.c:
o If a mac address for the interface cannot be found
in the front-side XenStore tree, look for an entry
in the back-side tree. With ioemu devices, the
emulator does not populate the front side tree and
neither does Xend.
o Return an error rather than panic when an attach
attempt fails.

Reported by: Janne Snabb (fix inspired by patch provided)
PR: kern/154302
Approved by: re

Correct suspend/resume support in the Netfront driver.

Sponsored by: BQ Internet

sys/dev/xen/netfront/netfront.c:
o Implement netfront_suspend(), a specialized suspend
handler for the netfront driver. This routine simply
disables the carrier so the driver is idle during
system suspend processing.
o Fix a leak when re-initializing LRO during a link reset.
o In netif_release_tx_bufs(), when cleaning up the grant
references for our TX ring, use gnttab_end_foreign_access_ref
instead of attempting to grant the page again.
o In netif_release_tx_bufs(), we do not track mbufs associated
with mbuf chains, but instead just free each mbuf directly.
Use m_free(), not m_freem(), to avoid double frees of mbufs.
o Refactor some code to enhance clarity.

Approved by: re
MFC after: 1 week

Add suspend/resume support to the Xen blkfront driver.

Sponsored by: BQ Internet

sys/dev/xen/blkfront/block.h:
sys/dev/xen/blkfront/blkfront.c:
Remove now unused blkif_vdev_t from the blkfront soft.

sys/dev/xen/blkfront/blkfront.c:
o In blkfront_suspend(), indicate the desire to suspend
by changing the softc connected state to SUSPENDED, and
then wait for any I/O pending on the remote peer to
drain. Cancel suspend processing if I/O does not
drain within 30 seconds.
o Enable and update blkfront_resume(). Since I/O is
drained prior to the suspension of the VM, the complicated
recovery process performed by other Xen blkfront
implementations is avoided. We simply tear down the
connection to our old peer, and then re-connect.
o In blkif_initialize(), fix a resource leak and botched
return if we cannot allocate shadow memory for our
requests.
o In blkfront_backend_changed(), correct our response to
the XenbusStateInitialised state. This state indicates
that our backend peer has published sufficient data for
blkfront to publish ring information and other XenStore
data, not that a connection can occur. Blkfront now
will only perform connection processing in response to
the XenbusStateConnected state. This corrects an issue
where blkfront connected before the backend was ready
during resume processing.

Approved by: re
MFC after: 1 week

Properly handle suspend/resume events in the Xen device
framework.

Sponsored by: BQ Internet

sys/xen/xenbus/xenbusb.c:
o In xenbusb_resume(), publish the state transition of the
resuming device into XenbusStateIntiailising so that the
remote peer can see it. Recording the state locally is
not sufficient to trigger a re-connect sequence.
o In xenbusb_resume(), defer new-bus resume processing until
after the remote peer's XenStore address has been updated.
The drivers may need to refer to this information during
resume processing.

sys/xen/xenbus/xenbusb_back.c:
sys/xen/xenbus/xenbusb_front.c:
Register xenbusb_resume() rather than bus_generic_resume()
as the handler for device_resume events.

sys/xen/xenstore/xenstore.c:
o Fix grammer in a comment.
o In xs_suspend(), pass suspend events on to the child
devices (e.g. xenbusb_front/back, that are attached
to the XenStore.

Approved by: re
MFC after: 1 week

Add support for alternative break-to-debugger support on the Xen console.
This should help debug boot-time hangs experienced in 9.0-BETA.

MFC after: 3 weeks
Tested by: sbruno
Approved by: re (kib)

With retirement of cpumask_t and usage of cpuset_t for representing a
mask of CPUs, pc_other_cpus and pc_cpumask become highly inefficient.

Remove them and replace their usage with custom pc_cpuid magic (as,
atm, pc_cpumask can be easilly represented by (1 << pc_cpuid) and
pc_other_cpus by (all_cpus & ~(1 << pc_cpuid))).

This change is not targeted for MFC because of struct pcpu members
removal and dependency by cpumask_t retirement.

MD review by: marcel, marius, alc
Tested by: pluknet
MD testing by: marcel, marius, gonzo, andreast

Several enhancements to the Xen block back driver.

sys/dev/xen/blkback/blkback.c:
o Implement front-end request coalescing. This greatly improves the
performance of front-end clients that are unaware of the dynamic
request-size/number of requests negotiation available in the
FreeBSD backend driver. This required a large restructuring
in how this driver records in-flight transactions and how those
transactions are mapped into kernel KVA. For example, the driver
now includes a mini "KVA manager" that allocates ranges of
contiguous KVA to patches of requests that are physically
contiguous in the backing store so that a single bio or UIO
segment can be used to represent the I/O.

o Refuse to open any backend files or devices if the system
has yet to mount root. This avoids a panic.

o Properly handle "onlined" devices. An "onlined" backend
device stays attached to its backing store across front-end
disconnections. This feature is intended to reduce latency
when a front-end does a hand-off to another driver (e.g.
PV aware bootloader to OS kernel) or during a VM reboot.

o Harden the driver against a pathological/buggy front-end
by carefully vetting front-end XenStore data such as the
front-end state.

o Add sysctls that report the negotiated number of
segments per-request and the number of requests that
can be concurrently in flight.

Submitted by: kdm
Reviewed by: gibbs
Sponsored by: Spectra Logic Corporation
MFC after: 1 week

Monitor and emit events for XenStore changes to XenBus trees
of the devices we manage. These changes can be due to writes
we make ourselves or due to changes made by the control domain.
The goal of these changes is to insure that all state transitions
can be detected regardless of their source and to allow common
device policies (e.g. "onlined" backend devices) to be centralized
in the XenBus bus code.

sys/xen/xenbus/xenbusvar.h:
sys/xen/xenbus/xenbus.c:
sys/xen/xenbus/xenbus_if.m:
Add a new method for XenBus drivers "localend_changed".
This method is invoked whenever a write is detected to
a device's XenBus tree. The default implementation of
this method is a no-op.

sys/xen/xenbus/xenbus_if.m:
sys/dev/xen/netfront/netfront.c:
sys/dev/xen/blkfront/blkfront.c:
sys/dev/xen/blkback/blkback.c:
Change the signature of the "otherend_changed" method.
This notification cannot fail, so it should return void.

sys/xen/xenbus/xenbusb_back.c:
Add "online" device handling to the XenBus Back Bus
support code. An online backend device remains active
after a front-end detaches as a reconnect is expected
to occur in the near future.

sys/xen/interface/io/xenbus.h:
Add comment block further explaining the meaning and
driver responsibilities associated with the XenBus
Closed state.

sys/xen/xenbus/xenbusb.c:
sys/xen/xenbus/xenbusb.h:
sys/xen/xenbus/xenbusb_back.c:
sys/xen/xenbus/xenbusb_front.c:
sys/xen/xenbus/xenbusb_if.m:
o Register a XenStore watch against the local XenBus tree
for all devices.
o Cache the string length of the path to our local tree.
o Allow the xenbus front and back drivers to hook/filter both
local and otherend watch processing.
o Update the device ivar version of "state" when we detect
a XenStore update of that node.

sys/dev/xen/control/control.c:
sys/xen/xenbus/xenbus.c:
sys/xen/xenbus/xenbusb.c:
sys/xen/xenbus/xenbusb.h:
sys/xen/xenbus/xenbusvar.h:
sys/xen/xenstore/xenstorevar.h:
Allow clients of the XenStore watch mechanism to attach
a single uintptr_t worth of client data to the watch.
This removes the need to carefully place client watch
data within enclosing objects so that a cast or offsetof
calculation can be used to convert from watch to enclosing
object.

Sponsored by: Spectra Logic Corporation
MFC after: 1 week

etire the cpumask_t type and replace it with cpuset_t usage.

This is intended to fix the bug where cpu mask objects are
capped to 32. MAXCPU, then, can now arbitrarely bumped to whatever
value. Anyway, as long as several structures in the kernel are
statically allocated and sized as MAXCPU, it is suggested to keep it
as low as possible for the time being.

Technical notes on this commit itself:
- More functions to handle with cpuset_t objects are introduced.
The most notable are cpusetobj_ffs() (which calculates a ffs(3)
for a cpuset_t object), cpusetobj_strprint() (which prepares a string
representing a cpuset_t object) and cpusetobj_strscan() (which
creates a valid cpuset_t starting from a string representation).
- pc_cpumask and pc_other_cpus are target to be removed soon.
With the moving from cpumask_t to cpuset_t they are now inefficient
and not really useful. Anyway, for the time being, please note that
access to pcpu datas is protected by sched_pin() in order to avoid
migrating the CPU while reading more than one (possible) word
- Please note that size of cpuset_t objects may differ between kernel
and userland. While this is not directly related to the patch itself,
it is good to understand that concept and possibly use the patch
as a reference on how to deal with cpuset_t objects in userland, when
accessing kernland members.
- KTR_CPUMASK is changed and now is represented through a string, to be
set as the example reported in NOTES.

Please additively note that no MAXCPU is bumped in this patch, but
private testing has been done until to MAXCPU=128 on a real 8x8x2(htt)
machine (amd64).

Please note that the FreeBSD version is not yet bumped because of
the upcoming pcpu changes. However, note that this patch is not
targeted for MFC.

People to thank for the time spent on this patch:
- sbruno, pluknet and Nicholas Esborn (nick AT desert DOT net) tested
several revision of the patches and really helped in improving
stability of this work.
- marius fixed several bugs in the sparc64 implementation and reviewed
patches related to ktr.
- jeff and jhb discussed the basic approach followed.
- kib and marcel made targeted review on some specific part of the
patch.
- marius, art, nwhitehorn and andreast reviewed MD specific part of
the patch.
- marius, andreast, gonzo, nwhitehorn and jceel tested MD specific
implementations of the patch.
- Other people have made contributions on other patches that have been
already committed and have been listed separately.

Companies that should be mentioned for having participated at several
degrees:
- Yahoo! for having offered the machines used for testing on big
count of CPUs.
- The FreeBSD Foundation for having sponsored my devsummit attendance,
which has been instrumental.
- Sandvine for having offered offices and infrastructure during
development.

(I really hope I didn't forget anyone, if it happened I apologize in
advance).

Fix msleep() usage in Xen balloon driver to not wake up on every HZ tick.

Make various (pseudo) interfaces compile without INET in the kernel
adding appropriate #ifdefs. For module builds the framework needs
adjustments for at least carp.

Reviewed by: gnn
Sponsored by: The FreeBSD Foundation
Sponsored by: iXsystems
MFC after: 4 days

Fix bug in the netfront driver that caused excessive packet drops during
receive processing.

Remove unnecessary restrictions on the mbuf chain length built during an
LRO receive. This restriction was copied from the Linux netfront driver
where the LRO implementation cannot handle more than 18 discontinuities.
The FreeBSD implementation has no such restriction.

MFC after: 1 week

Fix a few more SYSCTL_PROC() that were missing a CTLFLAG type specifier.

Make "options XENHVM" compile for i386, not just amd64 -- a largely
mechanical change. This opens the door for using PV device drivers
under Xen HVM on i386, as well as more general harmonisation of i386
and amd64 Xen support in FreeBSD.

Reviewed by: cperciva
MFC after: 3 weeks

A lack of console input is not the same thing as a byte of \0 input.
Correctly return -1 from cngetc when no input is available to be read.

This fixes the '(CTRL-C to abort)' spam while dumping.

MFC after: 3 days

Set correct maximum I/O length. We can only handle I/O of up to
max_request_segments * PAGE_SIZE if the I/O is page-aligned; the
largest I/O we can guarantee will work is PAGE_SIZE less than that.
This unbreaks 'diskinfo -t'.

Purge mergeinfo on sys/dev/xen/xenpci. The only unique mergeinfo compared
to head was not useful (it came in with the merge from /user/dfr/xenhvm/7
and that mergeinfo is still present at sys/) and not worth keeping an extra
set of mergeinfo around in the kernel.

Remove some bogus, self-referential mergeinfo.

sys/dev/xen/blkback/blkback.c:
In xbb_detach() only perform cleanup of our taskqueue and
device statistics structures if they have been initialized.
This avoids a panic when xbb_detach() is called on a partially
initialized device instance, due to an early failure in
attach.

Sponsored by: Spectra Logic Corporation

Improve the Xen para-virtualized device infrastructure of FreeBSD:

o Add support for backend devices (e.g. blkback)
o Implement extensions to the Xen para-virtualized block API to allow
for larger and more outstanding I/Os.
o Import a completely rewritten block back driver with support for fronting
I/O to both raw devices and files.
o General cleanup and documentation of the XenBus and XenStore support code.
o Robustness and performance updates for the block front driver.
o Fixes to the netfront driver.

Sponsored by: Spectra Logic Corporation

sys/xen/xenbus/init.txt:
Deleted: This file explains the Linux method for XenBus device
enumeration and thus does not apply to FreeBSD's NewBus approach.

sys/xen/xenbus/xenbus_probe_backend.c:
Deleted: Linux version of backend XenBus service routines. It
was never ported to FreeBSD. See xenbusb.c, xenbusb_if.m,
xenbusb_front.c xenbusb_back.c for details of FreeBSD's XenBus
support.

sys/xen/xenbus/xenbusvar.h:
sys/xen/xenbus/xenbus_xs.c:
sys/xen/xenbus/xenbus_comms.c:
sys/xen/xenbus/xenbus_comms.h:
sys/xen/xenstore/xenstorevar.h:
sys/xen/xenstore/xenstore.c:
Split XenStore into its own tree. XenBus is a software layer built
on top of XenStore. The old arrangement and the naming of some
structures and functions blurred these lines making it difficult to
discern what services are provided by which layer and at what times
these services are available (e.g. during system startup and shutdown).

sys/xen/xenbus/xenbus_client.c:
sys/xen/xenbus/xenbus.c:
sys/xen/xenbus/xenbus_probe.c:
sys/xen/xenbus/xenbusb.c:
sys/xen/xenbus/xenbusb.h:
Split up XenBus code into methods available for use by client
drivers (xenbus.c) and code used by the XenBus "bus code" to
enumerate, attach, detach, and service bus drivers.

sys/xen/reboot.c:
sys/dev/xen/control/control.c:
Add a XenBus front driver for handling shutdown, reboot, suspend, and
resume events published in the XenStore. Move all PV suspend/reboot
support from reboot.c into this driver.

sys/xen/blkif.h:
New file from Xen vendor with macros and structures used by
a block back driver to service requests from a VM running a
different ABI (e.g. amd64 back with i386 front).

sys/conf/files:
Adjust kernel build spec for new XenBus/XenStore layout and added
Xen functionality.

sys/dev/xen/balloon/balloon.c:
sys/dev/xen/netfront/netfront.c:
sys/dev/xen/blkfront/blkfront.c:
sys/xen/xenbus/...
sys/xen/xenstore/...
o Rename XenStore APIs and structures from xenbus_* to xs_*.
o Adjust to use of M_XENBUS and M_XENSTORE malloc types for allocation
of objects returned by these APIs.
o Adjust for changes in the bus interface for Xen drivers.

sys/xen/xenbus/...
sys/xen/xenstore/...
Add Doxygen comments for these interfaces and the code that
implements them.

sys/dev/xen/blkback/blkback.c:
o Rewrite the Block Back driver to attach properly via newbus,
operate correctly in both PV and HVM mode regardless of domain
(e.g. can be in a DOM other than 0), and to deal with the latest
metadata available in XenStore for block devices.

o Allow users to specify a file as a backend to blkback, in addition
to character devices. Use the namei lookup of the backend path
to automatically configure, based on file type, the appropriate
backend method.

The current implementation is limited to a single outstanding I/O
at a time to file backed storage.

sys/dev/xen/blkback/blkback.c:
sys/xen/interface/io/blkif.h:
sys/xen/blkif.h:
sys/dev/xen/blkfront/blkfront.c:
sys/dev/xen/blkfront/block.h:
Extend the Xen blkif API: Negotiable request size and number of
requests.

This change extends the information recorded in the XenStore
allowing block front/back devices to negotiate for optimal I/O
parameters. This has been achieved without sacrificing backward
compatibility with drivers that are unaware of these protocol
enhancements. The extensions center around the connection protocol
which now includes these additions:

o The back-end device publishes its maximum supported values for,
request I/O size, the number of page segments that can be
associated with a request, the maximum number of requests that
can be concurrently active, and the maximum number of pages that
can be in the shared request ring. These values are published
before the back-end enters the XenbusStateInitWait state.

o The front-end waits for the back-end to enter either the InitWait
or Initialize state. At this point, the front end limits it's
own capabilities to the lesser of the values it finds published
by the backend, it's own maximums, or, should any back-end data
be missing in the store, the values supported by the original
protocol. It then initializes it's internal data structures
including allocation of the shared ring, publishes its maximum
capabilities to the XenStore and transitions to the Initialized
state.

o The back-end waits for the front-end to enter the Initalized
state. At this point, the back end limits it's own capabilities
to the lesser of the values it finds published by the frontend,
it's own maximums, or, should any front-end data be missing in
the store, the values supported by the original protocol. It
then initializes it's internal data structures, attaches to the
shared ring and transitions to the Connected state.

o The front-end waits for the back-end to enter the Connnected
state, transitions itself to the connected state, and can
commence I/O.

Although an updated front-end driver must be aware of the back-end's
InitWait state, the back-end has been coded such that it can
tolerate a front-end that skips this step and transitions directly
to the Initialized state without waiting for the back-end.

sys/xen/interface/io/blkif.h:
o Increase BLKIF_MAX_SEGMENTS_PER_REQUEST to 255. This is
the maximum number possible without changing the blkif
request header structure (nr_segs is a uint8_t).

o Add two new constants:
BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK, and
BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK. These respectively
indicate the number of segments that can fit in the first
ring-buffer entry of a request, and for each subsequent
(sg element only) ring-buffer entry associated with the
"header" ring-buffer entry of the request.

o Add the blkif_request_segment_t typedef for segment
elements.

o Add the BLKRING_GET_SG_REQUEST() macro which wraps the
RING_GET_REQUEST() macro and returns a properly cast
pointer to an array of blkif_request_segment_ts.

o Add the BLKIF_SEGS_TO_BLOCKS() macro which calculates the
number of ring entries that will be consumed by a blkif
request with the given number of segments.

sys/xen/blkif.h:
o Update for changes in interface/io/blkif.h macros.

o Update the BLKIF_MAX_RING_REQUESTS() macro to take the
ring size as an argument to allow this calculation on
multi-page rings.

o Add a companion macro to BLKIF_MAX_RING_REQUESTS(),
BLKIF_RING_PAGES(). This macro determines the number of
ring pages required in order to support a ring with the
supplied number of request blocks.

sys/dev/xen/blkback/blkback.c:
sys/dev/xen/blkfront/blkfront.c:
sys/dev/xen/blkfront/block.h:
o Negotiate with the other-end with the following limits:
Reqeust Size: MAXPHYS
Max Segments: (MAXPHYS/PAGE_SIZE) + 1
Max Requests: 256
Max Ring Pages: Sufficient to support Max Requests with
Max Segments.

o Dynamically allocate request pools and segemnts-per-request.

o Update ring allocation/attachment code to support a
multi-page shared ring.

o Update routines that access the shared ring to handle
multi-block requests.

sys/dev/xen/blkfront/blkfront.c:
o Track blkfront allocations in a blkfront driver specific
malloc pool.

o Strip out XenStore transaction retry logic in the
connection code. Transactions only need to be used when
the update to multiple XenStore nodes must be atomic.
That is not the case here.

o Fully disable blkif_resume() until it can be fixed
properly (it didn't work before this change).

o Destroy bus-dma objects during device instance tear-down.

o Properly handle backend devices with powef-of-2 sector
sizes larger than 512b.

sys/dev/xen/blkback/blkback.c:
Advertise support for and implement the BLKIF_OP_WRITE_BARRIER
and BLKIF_OP_FLUSH_DISKCACHE blkif opcodes using BIO_FLUSH and
the BIO_ORDERED attribute of bios.

sys/dev/xen/blkfront/blkfront.c:
sys/dev/xen/blkfront/block.h:
Fix various bugs in blkfront.

o gnttab_alloc_grant_references() returns 0 for success and
non-zero for failure. The check for < 0 is a leftover
Linuxism.

o When we negotiate with blkback and have to reduce some of our
capabilities, print out the original and reduced capability before
changing the local capability. So the user now gets the correct
information.

o Fix blkif_restart_queue_callback() formatting. Make sure we hold
the mutex in that function before calling xb_startio().

o Fix a couple of KASSERT()s.

o Fix a check in the xb_remove_* macro to be a little more specific.

sys/xen/gnttab.h:
sys/xen/gnttab.c:
Define GNTTAB_LIST_END publicly as GRANT_REF_INVALID.

sys/dev/xen/netfront/netfront.c:
Use GRANT_REF_INVALID instead of driver private definitions of the
same constant.

sys/xen/gnttab.h:
sys/xen/gnttab.c:
Add the gnttab_end_foreign_access_references() API.

This API allows a client to batch the release of an array of grant
references, instead of coding a private for loop. The implementation
takes advantage of this batching to reduce lock overhead to one
acquisition and release per-batch instead of per-freed grant reference.

While here, reduce the duration the gnttab_list_lock is held during
gnttab_free_grant_references() operations. The search to find the
tail of the incoming free list does not rely on global state and so
can be performed without holding the lock.

sys/dev/xen/xenpci/evtchn.c:
sys/dev/xen/evtchn/evtchn.c:
sys/xen/xen_intr.h:
o Implement the bind_interdomain_evtchn_to_irqhandler API for HVM mode.
This allows an HVM domain to serve back end devices to other domains.
This API is already implemented for PV mode.

o Synchronize the API between HVM and PV.

sys/dev/xen/xenpci/xenpci.c:
o Scan the full region of CPUID space in which the Xen VMM interface
may be implemented. On systems using SuSE as a Dom0 where the
Viridian API is also exported, the VMM interface is above the region
we used to search.

o Pass through bus_alloc_resource() calls so that XenBus drivers
attaching on an HVM system can allocate unused physical address
space from the nexus. The block back driver makes use of this
facility.

sys/i386/xen/xen_machdep.c:
Use the correct type for accessing the statically mapped xenstore
metadata.

sys/xen/interface/hvm/params.h:
sys/xen/xenstore/xenstore.c:
Move hvm_get_parameter() to the correct global header file instead
of as a private method to the XenStore.

sys/xen/interface/io/protocols.h:
Sync with vendor.

sys/xeninterface/io/ring.h:
Add macro for calculating the number of ring pages needed for an N
deep ring.

To avoid duplication within the macros, create and use the new
__RING_HEADER_SIZE() macro. This macro calculates the size of the
ring book keeping struct (producer/consumer indexes, etc.) that
resides at the head of the ring.

Add the __RING_PAGES() macro which calculates the number of shared
ring pages required to support a ring with the given number of
requests.

These APIs are used to support the multi-page ring version of the
Xen block API.

sys/xeninterface/io/xenbus.h:
Add Comments.

sys/xen/xenbus/...
o Refactor the FreeBSD XenBus support code to allow for both front and
backend device attachments.

o Make use of new config_intr_hook capabilities to allow front and back
devices to be probed/attached in parallel.

o Fix bugs in probe/attach state machine that could cause the system to
hang when confronted with a failure either in the local domain or in
a remote domain to which one of our driver instances is attaching.

o Publish all required state to the XenStore on device detach and
failure. The majority of the missing functionality was for serving
as a back end since the typical "hot-plug" scripts in Dom0 don't
handle the case of cleaning up for a "service domain" that is not
itself.

o Add dynamic sysctl nodes exposing the generic ivars of
XenBus devices.

o Add doxygen style comments to the majority of the code.

o Cleanup types, formatting, etc.

sys/xen/xenbus/xenbusb.c:
Common code used by both front and back XenBus busses.

sys/xen/xenbus/xenbusb_if.m:
Method definitions for a XenBus bus.

sys/xen/xenbus/xenbusb_front.c:
sys/xen/xenbus/xenbusb_back.c:
XenBus bus specialization for front and back devices.

MFC after: 1 month

A number of netfront fixes and stability improvements:

- Re-enable TSO. This was broken previously due to CSUM_TSO clearing the
CSUM_TCP flag, so our checksum flags were incorrectly set going to the
netback driver. That was fixed in r206844 in tcp_output.c, so we can
turn TSO back on here.

- Fix the way transmit slots are calculated, so that we can't overfill
the ring.

- Avoid sending packets with more fragments/segments than netback can
handle. The Linux netback code can only handle packets of
MAX_SKB_FRAGS, which turns out to be 18 on machines with 4K pages. We
can easily generate packets with 32 or so fragments with TSO turned on.
Right now the solution is just to drop the packets (since netback
doesn't seem to handle it gracefully), but we should come up with a way
to allow a driver to tell the TCP stack the maximum number of fragments
it can handle in a single packet.

- Fix the way the consumer is tracked in the receive path. It could get
out of sync fairly easily.

- Use standard Xen ring macros to make it clearer how netfront is using
the rings.

- Get rid of Linux-ish negative errno return values.

- Added more documentation to the driver.

- Refactored code to make it easier to read.

- Some other minor fixes.

Reviewed by: gibbs

Reviewed by: gibbs
Sponsored by: Spectra Logic
MFC after: 7 days

Merger of the quota64 project into head.

This joint work of Dag-Erling Smørgrav and myself updates the
FFS quota system to support both traditional 32-bit and new 64-bit
quotas (for those of you who want to put 2+Tb quotas on your users).

By default quotas are not compiled into the kernel. To include them
in your kernel configuration you need to specify:

options QUOTA # Enable FFS quotas

If you are already running with the current 32-bit quotas, they
should continue to work just as they have in the past. If you
wish to convert to using 64-bit quotas, use `quotacheck -c 64';
if you wish to revert from 64-bit quotas back to 32-bit quotas,
use `quotacheck -c 32'.

There is a new library of functions to simplify the use of the
quota system, do `man quotafile' for details. If your application
is currently using the quotactl(2), it is highly recommended that
you convert your application to use the quotafile interface.
Note that existing binaries will continue to work.

Special thanks to John Kozubik of rsync.net for getting me
interested in pursuing 64-bit quota support and for funding
part of my development time on this project.

Switch to our preferred 2-clause BSD license.

Approved by: kmacy

The proper fix for the delayed SCTP checksum is to
have the delayed function take an argument as to the offset
to the SCTP header. This allows it to work for V4 and V6.
This of course means changing all callers of the function
to either pass the header len, if they have it, or create
it (ip_hl << 2 or sizeof(ip6_hdr)).
PR: 144529
MFC after: 2 weeks

- make printf conditional
- fix witness warnings by making configuration lock a mutex

In blkif_queue_cb(), test the return value from gnttab_claim_grant_reference()
for >= 0 instead of != ENOSPC.

Correct alignment and boundary constraints in blkfront's bus dma tag. The
blkif interface in Xen requires all I/O to be 512 byte aligned with each
segment bounded by a 4k page.

Note: This submission only documents the proper contraints for blkif I/O.
The alignment code in busdma does not yet handle alignment constraints
correctly in all cases.

Add media ioctl support and link notifications so that devd will attempt
to run dhclient on a netfront (xn) device that is setup for DHCP in
/etc/rc.conf.

PR: kern/136251 (fixed differently than the submitted patch)

Merge Scott Long's latest blkfront now that the licensing issues are resolved

Update license to reflect terms in xen 2.0 as of the time when the driver was ported
to FreeBSD

remove annoying printf that cripples kdb on PV guests

fixup kernel core dumps on paravirtual guests

Remove commented out reference to if_watchdog and an assignment of zero to
if_timer.

Reviewed by: scottl

add core dump support to blkfront

Obtained from: Frank Suchomel

Cleanups to the Xen console driver:

- Use CONSOLE_DRIVER() instead of the deprecated CONS_DRIVER() declaration.

- This means we cannot use cn_checkc anymore, which is supposed to do
the same as cn_getc nowadays. Remove the cn_getc implementation (that
was never being called) and rename cn_checkc to cn_getc.

- Don't run-time patch cn_putc, but add the logic to xc_cnputc().

This means I could do some cleanups to our console code...

Tested by: nobody on hackers@

Temporarily revert the new-bus locking for 8.0 release. It will be
reintroduced after HEAD is reopened for commits by re@.

Approved by: re (kib), attilio

- Remove self-referential mergeinfo from xen/netfront and xen/xenpci that
claims those directories were merged into themselves.
- Remove mergeinfo on xen/xenpci that claims the stable/7 xenpci was merged
into head.

Approved by: re (mergeinfo blanket)

Make the newbus subsystem Giant free by adding the new newbus sxlock.
The newbus lock is responsible for protecting newbus internIal structures,
device states and devclass flags. It is necessary to hold it when all
such datas are accessed. For the other operations, softc locking should
ensure enough protection to avoid races.

Newbus lock is automatically held when virtual operations on the device
and bus are invoked when loading the driver or when the suspend/resume
take place. For other 'spourious' operations trying to access/modify
the newbus topology, newbus lock needs to be automatically acquired and
dropped.

For the moment Giant is also acquired in some key point (modules subsystem)
in order to avoid problems before the 8.0 release as module handlers could
make assumptions about it. This Giant locking should go just after
the release happens.

Please keep in mind that the public interface can be expanded in order
to provide more support, if there are really necessities at some point
and also some bugs could arise as long as the patch needs a bit of
further testing.

Bump __FreeBSD_version in order to reflect the newbus lock introduction.

Reviewed by: ed, hps, jhb, imp, mav, scottl
No answer by: ariff, thompsa, yongari
Tested by: pho,
G. Trematerra <giovanni dot trematerra at gmail dot com>,
Brandon Gooch <jamesbrandongooch at gmail dot com>
Sponsored by: Yahoo! Incorporated
Approved by: re (ksmith)

update backend_changed to reflect .m prototype

Fix compilation when compiled w/out WITNESS.

Submitted by: Edwin Shao <poleris@gmail.com>

Last minute TTY API change: remove mutex argument from tty_alloc().

I don't want people to override the mutex when allocating a TTY. It has
to be there, to keep drivers like syscons happy. So I'm creating a
tty_alloc_mutex() which can be used in those cases. tty_alloc_mutex()
should eventually be removed.

The advantage of this approach, is that we can just remove a function,
without breaking the regular API in the future.

Delete useless #ifdef; make it more obvious if setting TSO fails.

Clear IFF_DRV_OACTIVE if at least one TX xen/mbuf ring slot has been freed.

Enforce that there are actually enough xenbus TX ring descriptors available
before attempting to queue the packet.

Comment tidyup; comment where the next explicit check should
appear.

Ensure that there are enough TX mbuf ring slots available before beginning
to dequeue a packet.

The tx path was trying to ensure that enough Xenbus TX ring slots existed but
it didn't check to see whether the mbuf TX ring slots were also available.
They get freed in xn_txeof() which occurs after transmission, rather than earlier
on in the process. (The same happens under Linux too.)

Due to whatever reason (CPU use, scheduling, memory constraints, whatever) the
mbuf TX ring may not have enough slots free and would allocate slot 0. This is
used as the freelist head pointer to represent "free" mbuf TX ring slots; setting
this to an actual mbuf value rather than an id crashes the code.

This commit introduces some basic code to track the TX mbuf ring use and then
(hopefully!) ensures that enough slots are free in said TX mbuf ring before it
enters the actual work loop.

A few notes:

* Similar logic needs to be introduced to check there are enough actual slots
available in the xenbuf TX ring. There's some logic which is invoked earlier
but it doesn't hard-check against the number of available ring slots.
Its trivial to do; I'll do it in a subsequent commit.

* As I've now commented in the source, it is likely possible to deadlock the
driver under certain conditions where the rings aren't receiving any changes
(which I should enumerate) and thus Xen doesn't send any further software
interrupts. I need to make sure that the timer(s) are running right and
the queues are periodically kicked.

PR: 134926

Do the invariant check before the mbuf is dereferenced.

Flesh out some inline documentation which hopefully reflect the intended
reality of these functions.

Add in some INVARIANT checks in the TX mbuf descriptor "freelist" management code.

Slot 0 must always remain "free" and be a pointer to the first free entry in the
mbuf descriptor list. It is thus an error to have code allocate or push slot 0
back into the list.

The merge in r189699 reverted part of the work done in a previous commit
(r188036.)

Re-revert that change so the Xen networking functions again.

Disable some un-needed console debugging.

don't acquire tty lock with console lock held

xen console lock needs to be a spin lock in case it is acquired from an interrupt context

Implement an ipfw action to reassemble ip packets: reass.

Fix the Xen build for i386 PV mode.

Integrate user/mav/ata branch:

Add ch_suspend/ch_resume methods for PCI controllers and implement them
for AHCI. Refactor AHCI channel initialization according to it.

Fix Port Multipliers operation. It is far from perfect yet, but works now.
Tested with JMicron JMB363 AHCI + SiI 3726 PMP pair.
Previous version was also tested with SiI 4726 PMP.

Hardware sponsored by: Vitsch Electronics / VEHosting.nl

Merge in support for Xen HVM on amd64 architecture.

fix non-witness compile

Adds support for SCTP checksum offload. This means
we, like TCP and UDP, move the checksum calculation
into the IP routines when there is no hardware support
we call into the normal SCTP checksum routine.

The next round of SCTP updates will use
this functionality. Of course the IGB driver needs
a few updates to support the new intel controller set
that actually does SCTP csum offload too.

Reviewed by: gnn, rwatson, kmacy

break out of loop if we run out of mbufs

Last step of splitting up minor and unit numbers: remove minor().

Inside the kernel, the minor() function was responsible for obtaining
the device minor number of a character device. Because we made device
numbers dynamically allocated and independent of the unit number passed
to make_dev() a long time ago, it was actually a misnomer. If you really
want to obtain the device number, you should use dev2udev().

We already converted all the drivers to use dev2unit() to obtain the
device unit number, which is still used by a lot of drivers. I've
noticed not a single driver passes NULL to dev2unit(). Even if they
would, its behaviour would make little sense. This is why I've removed
the NULL check.

Ths commit removes minor(), minor2unit() and unit2minor() from the
kernel. Because there was a naming collision with uminor(), we can
rename umajor() and uminor() back to major() and minor(). This means
that the makedev(3) manual page also applies to kernel space code now.

I suspect umajor() and uminor() isn't used that often in external code,
but to make it easier for other parties to port their code, I've
increased __FreeBSD_version to 800062.

merge 186535, 186537, and 186538 from releng_7_xen

Log:
- merge in latest xenbus from dfr's xenhvm
- fix race condition in xs_read_reply by converting tsleep to mtx_sleep

Log:
unmask evtchn in bind_{virq, ipi}_to_irq

Log:
- remove code for handling case of not being able to sleep
- eliminate tsleep - make sleeps atomic

Integrate 185578 from dfr
Use newbus to managed devices

Don't call ether_ioctl() with locks held. Loop in xn_rxeof() until the backend
stops adding stuff to the ring otherwise we miss RX interrupts which kills
performance.

Remove unused consdev structure fields.

The cn_unit and cn_tp fields don't seem to be used anywhere. Some
drivers set them, while others don't. Just remove them, in an attempt to
make our consdev code a little easier to understand.

Replace all calls to minor() with dev2unit().

After I removed all the unit2minor()/minor2unit() calls from the kernel
yesterday, I realised calling minor() everywhere is quite confusing.
Character devices now only have the ability to store a unit number, not
a minor number. Remove the confusion by using dev2unit() everywhere.

This commit could also be considered as a bug fix. A lot of drivers call
minor(), while they should actually be calling dev2unit(). In -CURRENT
this isn't a problem, but it turns out we never had any problem reports
related to that issue in the past. I suspect not many people connect
more than 256 pieces of the same hardware.

Reviewed by: kib

Update xen/interface includes to the latest in mercurial

MFC after: 1 month

reflect header change in netfront

MFC after: 1 month

Decontextualize the couplet VOP_GETATTR / VOP_SETATTR as the passed thread
was always curthread and totally unuseful.

Tested by: Giovanni Trematerra <giovanni dot trematerra at gmail dot com>

Evidently the block device starts at 767.

MFC after: 1 month

make block devices start at 0

For reasons that I have not delved in to Xen 3.2 netback now does header splitting
so packets > 128 bytes are now split in to multiple buffer. This fixes netfront
to handle multiple buffers per rx packet.

MFC after: 1 month

change netfront to match xen31_6
fix console locking

mark blkfront_info as ready

MFC after: 1 month

include vmparam.h for KERNBASE and fix typo

register netfront before xenbus does its probing

MFC after: 1 month

Integrate the Xen console driver.

I initially didn't want to integrate the Xen console driver, because it
did not receive any testing. Kip Macy suggested that I'd better check it
in right now, because this is the easiest way for him to test it while
he is working on the Xen import.

Requested by: kmacy

Make sure that machine addresses are vm_paddr_t

MFC after: 1 month

Compile fixes for xen build.

MFC after: 1 month.

Import Xen paravirtual drivers.

MFC after: 2 weeks