1// SPDX-License-Identifier: MIT License
2/*
3 * hypervisor.c
4 *
5 * Communication to/from hypervisor.
6 *
7 * Copyright (c) 2002-2003, K A Fraser
8 * Copyright (c) 2005, Grzegorz Milos, gm281@cam.ac.uk,Intel Research Cambridge
9 * Copyright (c) 2020, EPAM Systems Inc.
10 */
11#include <common.h>
12#include <cpu_func.h>
13#include <log.h>
14#include <memalign.h>
15
16#include <asm/io.h>
17#include <asm/armv8/mmu.h>
18#include <asm/xen/system.h>
19
20#include <linux/bug.h>
21
22#include <xen/hvm.h>
23#include <xen/events.h>
24#include <xen/gnttab.h>
25#include <xen/xenbus.h>
26#include <xen/interface/memory.h>
27
28#define active_evtchns(cpu, sh, idx)	\
29	((sh)->evtchn_pending[idx] &	\
30	 ~(sh)->evtchn_mask[idx])
31
32int in_callback;
33
34/*
35 * Shared page for communicating with the hypervisor.
36 * Events flags go here, for example.
37 */
38struct shared_info *HYPERVISOR_shared_info;
39
40static const char *param_name(int op)
41{
42#define PARAM(x)[HVM_PARAM_##x] = #x
43	static const char *const names[] = {
44		PARAM(CALLBACK_IRQ),
45		PARAM(STORE_PFN),
46		PARAM(STORE_EVTCHN),
47		PARAM(PAE_ENABLED),
48		PARAM(IOREQ_PFN),
49		PARAM(VPT_ALIGN),
50		PARAM(CONSOLE_PFN),
51		PARAM(CONSOLE_EVTCHN),
52	};
53#undef PARAM
54
55	if (op >= ARRAY_SIZE(names))
56		return "unknown";
57
58	if (!names[op])
59		return "reserved";
60
61	return names[op];
62}
63
64/**
65 * hvm_get_parameter_maintain_dcache - function to obtain a HVM
66 * parameter value.
67 * @idx: HVM parameter index
68 * @value: Value to fill in
69 *
70 * According to Xen on ARM ABI (xen/include/public/arch-arm.h):
71 * all memory which is shared with other entities in the system
72 * (including the hypervisor and other guests) must reside in memory
73 * which is mapped as Normal Inner Write-Back Outer Write-Back
74 * Inner-Shareable.
75 *
76 * Thus, page attributes must be equally set for all the entities
77 * working with that page.
78 *
79 * Before MMU setup the data cache is turned off, so it means that
80 * manual data cache maintenance is required, because of the
81 * difference of page attributes.
82 */
83int hvm_get_parameter_maintain_dcache(int idx, uint64_t *value)
84{
85	struct xen_hvm_param xhv;
86	int ret;
87
88	invalidate_dcache_range((unsigned long)&xhv,
89				(unsigned long)&xhv + sizeof(xhv));
90	xhv.domid = DOMID_SELF;
91	xhv.index = idx;
92	invalidate_dcache_range((unsigned long)&xhv,
93				(unsigned long)&xhv + sizeof(xhv));
94
95	ret = HYPERVISOR_hvm_op(HVMOP_get_param, &xhv);
96	if (ret < 0) {
97		pr_err("Cannot get hvm parameter %s (%d): %d!\n",
98			   param_name(idx), idx, ret);
99		BUG();
100	}
101	invalidate_dcache_range((unsigned long)&xhv,
102				(unsigned long)&xhv + sizeof(xhv));
103
104	*value = xhv.value;
105
106	return ret;
107}
108
109int hvm_get_parameter(int idx, uint64_t *value)
110{
111	struct xen_hvm_param xhv;
112	int ret;
113
114	xhv.domid = DOMID_SELF;
115	xhv.index = idx;
116	ret = HYPERVISOR_hvm_op(HVMOP_get_param, &xhv);
117	if (ret < 0) {
118		pr_err("Cannot get hvm parameter %s (%d): %d!\n",
119			   param_name(idx), idx, ret);
120		BUG();
121	}
122
123	*value = xhv.value;
124
125	return ret;
126}
127
128struct shared_info *map_shared_info(void *p)
129{
130	struct xen_add_to_physmap xatp;
131
132	HYPERVISOR_shared_info = (struct shared_info *)memalign(PAGE_SIZE,
133								PAGE_SIZE);
134	if (!HYPERVISOR_shared_info)
135		BUG();
136
137	xatp.domid = DOMID_SELF;
138	xatp.idx = 0;
139	xatp.space = XENMAPSPACE_shared_info;
140	xatp.gpfn = virt_to_pfn(HYPERVISOR_shared_info);
141	if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp) != 0)
142		BUG();
143
144	return HYPERVISOR_shared_info;
145}
146
147void unmap_shared_info(void)
148{
149	xen_pfn_t shared_info_pfn = virt_to_pfn(HYPERVISOR_shared_info);
150	struct xen_remove_from_physmap xrfp = {0};
151	struct xen_memory_reservation reservation = {0};
152	xen_ulong_t nr_exts = 1;
153
154	xrfp.domid = DOMID_SELF;
155	xrfp.gpfn = shared_info_pfn;
156	if (HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrfp) != 0)
157		panic("Failed to unmap HYPERVISOR_shared_info\n");
158
159	/*
160	 * After removing from physmap there will be a hole in address space on
161	 * HYPERVISOR_shared_info address, so to free memory allocated with
162	 * memalign and prevent exceptions during access to this page we need to
163	 * fill this 4KB hole with XENMEM_populate_physmap before jumping to Linux.
164	 */
165	reservation.domid = DOMID_SELF;
166	reservation.extent_order = 0;
167	reservation.address_bits = 0;
168	set_xen_guest_handle(reservation.extent_start, &shared_info_pfn);
169	reservation.nr_extents = nr_exts;
170	if (HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation) != nr_exts)
171		panic("Failed to populate memory on HYPERVISOR_shared_info addr\n");
172
173	/* Now we can return this to memory allocator */
174	free(HYPERVISOR_shared_info);
175}
176
177void do_hypervisor_callback(struct pt_regs *regs)
178{
179	unsigned long l1, l2, l1i, l2i;
180	unsigned int port;
181	int cpu = 0;
182	struct shared_info *s = HYPERVISOR_shared_info;
183	struct vcpu_info *vcpu_info = &s->vcpu_info[cpu];
184
185	in_callback = 1;
186
187	vcpu_info->evtchn_upcall_pending = 0;
188	l1 = xchg(&vcpu_info->evtchn_pending_sel, 0);
189
190	while (l1 != 0) {
191		l1i = __ffs(l1);
192		l1 &= ~(1UL << l1i);
193
194		while ((l2 = active_evtchns(cpu, s, l1i)) != 0) {
195			l2i = __ffs(l2);
196			l2 &= ~(1UL << l2i);
197
198			port = (l1i * (sizeof(unsigned long) * 8)) + l2i;
199			do_event(port, regs);
200		}
201	}
202
203	in_callback = 0;
204}
205
206void force_evtchn_callback(void)
207{
208#ifdef XEN_HAVE_PV_UPCALL_MASK
209	int save;
210#endif
211	struct vcpu_info *vcpu;
212
213	vcpu = &HYPERVISOR_shared_info->vcpu_info[smp_processor_id()];
214#ifdef XEN_HAVE_PV_UPCALL_MASK
215	save = vcpu->evtchn_upcall_mask;
216#endif
217
218	while (vcpu->evtchn_upcall_pending) {
219#ifdef XEN_HAVE_PV_UPCALL_MASK
220		vcpu->evtchn_upcall_mask = 1;
221#endif
222		do_hypervisor_callback(NULL);
223#ifdef XEN_HAVE_PV_UPCALL_MASK
224		vcpu->evtchn_upcall_mask = save;
225#endif
226	};
227}
228
229void mask_evtchn(uint32_t port)
230{
231	struct shared_info *s = HYPERVISOR_shared_info;
232
233	synch_set_bit(port, &s->evtchn_mask[0]);
234}
235
236void unmask_evtchn(uint32_t port)
237{
238	struct shared_info *s = HYPERVISOR_shared_info;
239	struct vcpu_info *vcpu_info = &s->vcpu_info[smp_processor_id()];
240
241	synch_clear_bit(port, &s->evtchn_mask[0]);
242
243	/*
244	 * Just like a real IO-APIC we 'lose the interrupt edge' if the
245	 * channel is masked.
246	 */
247	if (synch_test_bit(port, &s->evtchn_pending[0]) &&
248	    !synch_test_and_set_bit(port / (sizeof(unsigned long) * 8),
249				    &vcpu_info->evtchn_pending_sel)) {
250		vcpu_info->evtchn_upcall_pending = 1;
251#ifdef XEN_HAVE_PV_UPCALL_MASK
252		if (!vcpu_info->evtchn_upcall_mask)
253#endif
254			force_evtchn_callback();
255	}
256}
257
258void clear_evtchn(uint32_t port)
259{
260	struct shared_info *s = HYPERVISOR_shared_info;
261
262	synch_clear_bit(port, &s->evtchn_pending[0]);
263}
264
265int xen_init(void)
266{
267	int el = current_el();
268
269	debug("%s\n", __func__);
270
271	if (el != 1) {
272		puts("XEN:\tnot running from EL1\n");
273		return 0;
274	}
275
276	map_shared_info(NULL);
277	init_events();
278	init_xenbus();
279	init_gnttab();
280
281	return 0;
282}
283
284void xen_fini(void)
285{
286	debug("%s\n", __func__);
287
288	fini_gnttab();
289	fini_xenbus();
290	fini_events();
291	unmap_shared_info();
292}
293