1 // SPDX-License-Identifier: GPL-2.0-only
2 #include "linux/types.h"
3 #include "linux/bitmap.h"
4 #include "linux/atomic.h"
5
6 #include "kvm_util.h"
7 #include "ucall_common.h"
8
9
10 #define GUEST_UCALL_FAILED -1
11
12 struct ucall_header {
13 DECLARE_BITMAP(in_use, KVM_MAX_VCPUS);
14 struct ucall ucalls[KVM_MAX_VCPUS];
15 };
16
17 int ucall_nr_pages_required(uint64_t page_size)
18 {
19 return align_up(sizeof(struct ucall_header), page_size) / page_size;
20 }
21
22 /*
23 * ucall_pool holds per-VM values (global data is duplicated by each VM), it
24 * must not be accessed from host code.
25 */
26 static struct ucall_header *ucall_pool;
27
28 void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
29 {
30 struct ucall_header *hdr;
31 struct ucall *uc;
32 vm_vaddr_t vaddr;
33 int i;
34
35 vaddr = vm_vaddr_alloc_shared(vm, sizeof(*hdr), KVM_UTIL_MIN_VADDR,
36 MEM_REGION_DATA);
37 hdr = (struct ucall_header *)addr_gva2hva(vm, vaddr);
38 memset(hdr, 0, sizeof(*hdr));
39
40 for (i = 0; i < KVM_MAX_VCPUS; ++i) {
41 uc = &hdr->ucalls[i];
42 uc->hva = uc;
43 }
44
45 write_guest_global(vm, ucall_pool, (struct ucall_header *)vaddr);
46
47 ucall_arch_init(vm, mmio_gpa);
48 }
49
50 static struct ucall *ucall_alloc(void)
51 {
52 struct ucall *uc;
53 int i;
54
55 if (!ucall_pool)
56 goto ucall_failed;
57
58 for (i = 0; i < KVM_MAX_VCPUS; ++i) {
59 if (!test_and_set_bit(i, ucall_pool->in_use)) {
60 uc = &ucall_pool->ucalls[i];
61 memset(uc->args, 0, sizeof(uc->args));
62 return uc;
63 }
64 }
65
66 ucall_failed:
67 /*
68 * If the vCPU cannot grab a ucall structure, make a bare ucall with a
69 * magic value to signal to get_ucall() that things went sideways.
70 * GUEST_ASSERT() depends on ucall_alloc() and so cannot be used here.
71 */
72 ucall_arch_do_ucall(GUEST_UCALL_FAILED);
73 return NULL;
74 }
75
76 static void ucall_free(struct ucall *uc)
77 {
78 /* Beware, here be pointer arithmetic. */
79 clear_bit(uc - ucall_pool->ucalls, ucall_pool->in_use);
80 }
81
82 void ucall_assert(uint64_t cmd, const char *exp, const char *file,
83 unsigned int line, const char *fmt, ...)
84 {
85 struct ucall *uc;
86 va_list va;
87
88 uc = ucall_alloc();
89 uc->cmd = cmd;
90
91 WRITE_ONCE(uc->args[GUEST_ERROR_STRING], (uint64_t)(exp));
92 WRITE_ONCE(uc->args[GUEST_FILE], (uint64_t)(file));
93 WRITE_ONCE(uc->args[GUEST_LINE], line);
94
95 va_start(va, fmt);
96 guest_vsnprintf(uc->buffer, UCALL_BUFFER_LEN, fmt, va);
97 va_end(va);
98
99 ucall_arch_do_ucall((vm_vaddr_t)uc->hva);
100
101 ucall_free(uc);
102 }
103
104 void ucall_fmt(uint64_t cmd, const char *fmt, ...)
105 {
106 struct ucall *uc;
107 va_list va;
108
109 uc = ucall_alloc();
110 uc->cmd = cmd;
111
112 va_start(va, fmt);
113 guest_vsnprintf(uc->buffer, UCALL_BUFFER_LEN, fmt, va);
114 va_end(va);
115
116 ucall_arch_do_ucall((vm_vaddr_t)uc->hva);
117
118 ucall_free(uc);
119 }
120
121 void ucall(uint64_t cmd, int nargs, ...)
122 {
123 struct ucall *uc;
124 va_list va;
125 int i;
126
127 uc = ucall_alloc();
128
129 WRITE_ONCE(uc->cmd, cmd);
130
131 nargs = min(nargs, UCALL_MAX_ARGS);
132
133 va_start(va, nargs);
134 for (i = 0; i < nargs; ++i)
135 WRITE_ONCE(uc->args[i], va_arg(va, uint64_t));
136 va_end(va);
137
138 ucall_arch_do_ucall((vm_vaddr_t)uc->hva);
139
140 ucall_free(uc);
141 }
142
143 uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
144 {
145 struct ucall ucall;
146 void *addr;
147
148 if (!uc)
149 uc = &ucall;
150
151 addr = ucall_arch_get_ucall(vcpu);
152 if (addr) {
153 TEST_ASSERT(addr != (void *)GUEST_UCALL_FAILED,
154 "Guest failed to allocate ucall struct");
155
156 memcpy(uc, addr, sizeof(*uc));
157 vcpu_run_complete_io(vcpu);
158 } else {
159 memset(uc, 0, sizeof(*uc));
160 }
161
162 return uc->cmd;
163 }
164
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