1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
|
// SPDX-License-Identifier: GPL-2.0
#include "kvm_util.h"
#include "processor.h"
#define VCPU_ID 1
#define MMIO_GPA 0x100000000ull
static void guest_code(void)
{
(void)READ_ONCE(*((uint64_t *)MMIO_GPA));
(void)READ_ONCE(*((uint64_t *)MMIO_GPA));
GUEST_ASSERT(0);
}
static void guest_pf_handler(struct ex_regs *regs)
{
/* PFEC == RSVD | PRESENT (read, kernel). */
GUEST_ASSERT(regs->error_code == 0x9);
GUEST_DONE();
}
static void mmu_role_test(u32 *cpuid_reg, u32 evil_cpuid_val)
{
u32 good_cpuid_val = *cpuid_reg;
struct kvm_run *run;
struct kvm_vm *vm;
uint64_t cmd;
int r;
/* Create VM */
vm = vm_create_default(VCPU_ID, 0, guest_code);
run = vcpu_state(vm, VCPU_ID);
/* Map 1gb page without a backing memlot. */
__virt_pg_map(vm, MMIO_GPA, MMIO_GPA, PG_LEVEL_1G);
r = _vcpu_run(vm, VCPU_ID);
/* Guest access to the 1gb page should trigger MMIO. */
TEST_ASSERT(r == 0, "vcpu_run failed: %d\n", r);
TEST_ASSERT(run->exit_reason == KVM_EXIT_MMIO,
"Unexpected exit reason: %u (%s), expected MMIO exit (1gb page w/o memslot)\n",
run->exit_reason, exit_reason_str(run->exit_reason));
TEST_ASSERT(run->mmio.len == 8, "Unexpected exit mmio size = %u", run->mmio.len);
TEST_ASSERT(run->mmio.phys_addr == MMIO_GPA,
"Unexpected exit mmio address = 0x%llx", run->mmio.phys_addr);
/*
* Effect the CPUID change for the guest and re-enter the guest. Its
* access should now #PF due to the PAGE_SIZE bit being reserved or
* the resulting GPA being invalid. Note, kvm_get_supported_cpuid()
* returns the struct that contains the entry being modified. Eww.
*/
*cpuid_reg = evil_cpuid_val;
vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
/*
* Add a dummy memslot to coerce KVM into bumping the MMIO generation.
* KVM does not "officially" support mucking with CPUID after KVM_RUN,
* and will incorrectly reuse MMIO SPTEs. Don't delete the memslot!
* KVM x86 zaps all shadow pages on memslot deletion.
*/
vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
MMIO_GPA << 1, 10, 1, 0);
/* Set up a #PF handler to eat the RSVD #PF and signal all done! */
vm_init_descriptor_tables(vm);
vcpu_init_descriptor_tables(vm, VCPU_ID);
vm_install_exception_handler(vm, PF_VECTOR, guest_pf_handler);
r = _vcpu_run(vm, VCPU_ID);
TEST_ASSERT(r == 0, "vcpu_run failed: %d\n", r);
cmd = get_ucall(vm, VCPU_ID, NULL);
TEST_ASSERT(cmd == UCALL_DONE,
"Unexpected guest exit, exit_reason=%s, ucall.cmd = %lu\n",
exit_reason_str(run->exit_reason), cmd);
/*
* Restore the happy CPUID value for the next test. Yes, changes are
* indeed persistent across VM destruction.
*/
*cpuid_reg = good_cpuid_val;
kvm_vm_free(vm);
}
int main(int argc, char *argv[])
{
struct kvm_cpuid_entry2 *entry;
int opt;
/*
* All tests are opt-in because TDP doesn't play nice with reserved #PF
* in the GVA->GPA translation. The hardware page walker doesn't let
* software change GBPAGES or MAXPHYADDR, and KVM doesn't manually walk
* the GVA on fault for performance reasons.
*/
bool do_gbpages = false;
bool do_maxphyaddr = false;
setbuf(stdout, NULL);
while ((opt = getopt(argc, argv, "gm")) != -1) {
switch (opt) {
case 'g':
do_gbpages = true;
break;
case 'm':
do_maxphyaddr = true;
break;
case 'h':
default:
printf("usage: %s [-g (GBPAGES)] [-m (MAXPHYADDR)]\n", argv[0]);
break;
}
}
if (!do_gbpages && !do_maxphyaddr) {
print_skip("No sub-tests selected");
return 0;
}
entry = kvm_get_supported_cpuid_entry(0x80000001);
if (!(entry->edx & CPUID_GBPAGES)) {
print_skip("1gb hugepages not supported");
return 0;
}
if (do_gbpages) {
pr_info("Test MMIO after toggling CPUID.GBPAGES\n\n");
mmu_role_test(&entry->edx, entry->edx & ~CPUID_GBPAGES);
}
if (do_maxphyaddr) {
pr_info("Test MMIO after changing CPUID.MAXPHYADDR\n\n");
entry = kvm_get_supported_cpuid_entry(0x80000008);
mmu_role_test(&entry->eax, (entry->eax & ~0xff) | 0x20);
}
return 0;
}
|
