tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2020, Google LLC.
4 *
5 * Tests for KVM paravirtual feature disablement
6 */
7#include <asm/kvm_para.h>
8#include <linux/kvm_para.h>
9#include <stdint.h>
10
11#include "test_util.h"
12#include "kvm_util.h"
13#include "processor.h"
14
15struct msr_data {
16 uint32_t idx;
17 const char *name;
18};
19
20#define TEST_MSR(msr) { .idx = msr, .name = #msr }
21#define UCALL_PR_MSR 0xdeadbeef
22#define PR_MSR(msr) ucall(UCALL_PR_MSR, 1, msr)
23
24/*
25 * KVM paravirtual msrs to test. Expect a #GP if any of these msrs are read or
26 * written, as the KVM_CPUID_FEATURES leaf is cleared.
27 */
28static struct msr_data msrs_to_test[] = {
29 TEST_MSR(MSR_KVM_SYSTEM_TIME),
30 TEST_MSR(MSR_KVM_SYSTEM_TIME_NEW),
31 TEST_MSR(MSR_KVM_WALL_CLOCK),
32 TEST_MSR(MSR_KVM_WALL_CLOCK_NEW),
33 TEST_MSR(MSR_KVM_ASYNC_PF_EN),
34 TEST_MSR(MSR_KVM_STEAL_TIME),
35 TEST_MSR(MSR_KVM_PV_EOI_EN),
36 TEST_MSR(MSR_KVM_POLL_CONTROL),
37 TEST_MSR(MSR_KVM_ASYNC_PF_INT),
38 TEST_MSR(MSR_KVM_ASYNC_PF_ACK),
39};
40
41static void test_msr(struct msr_data *msr)
42{
43 uint64_t ignored;
44 uint8_t vector;
45
46 PR_MSR(msr);
47
48 vector = rdmsr_safe(msr->idx, &ignored);
49 GUEST_ASSERT_EQ(vector, GP_VECTOR);
50
51 vector = wrmsr_safe(msr->idx, 0);
52 GUEST_ASSERT_EQ(vector, GP_VECTOR);
53}
54
55struct hcall_data {
56 uint64_t nr;
57 const char *name;
58};
59
60#define TEST_HCALL(hc) { .nr = hc, .name = #hc }
61#define UCALL_PR_HCALL 0xdeadc0de
62#define PR_HCALL(hc) ucall(UCALL_PR_HCALL, 1, hc)
63
64/*
65 * KVM hypercalls to test. Expect -KVM_ENOSYS when called, as the corresponding
66 * features have been cleared in KVM_CPUID_FEATURES.
67 */
68static struct hcall_data hcalls_to_test[] = {
69 TEST_HCALL(KVM_HC_KICK_CPU),
70 TEST_HCALL(KVM_HC_SEND_IPI),
71 TEST_HCALL(KVM_HC_SCHED_YIELD),
72};
73
74static void test_hcall(struct hcall_data *hc)
75{
76 uint64_t r;
77
78 PR_HCALL(hc);
79 r = kvm_hypercall(hc->nr, 0, 0, 0, 0);
80 GUEST_ASSERT_EQ(r, -KVM_ENOSYS);
81}
82
83static void guest_main(void)
84{
85 int i;
86
87 for (i = 0; i < ARRAY_SIZE(msrs_to_test); i++) {
88 test_msr(&msrs_to_test[i]);
89 }
90
91 for (i = 0; i < ARRAY_SIZE(hcalls_to_test); i++) {
92 test_hcall(&hcalls_to_test[i]);
93 }
94
95 GUEST_DONE();
96}
97
98static void pr_msr(struct ucall *uc)
99{
100 struct msr_data *msr = (struct msr_data *)uc->args[0];
101
102 pr_info("testing msr: %s (%#x)\n", msr->name, msr->idx);
103}
104
105static void pr_hcall(struct ucall *uc)
106{
107 struct hcall_data *hc = (struct hcall_data *)uc->args[0];
108
109 pr_info("testing hcall: %s (%lu)\n", hc->name, hc->nr);
110}
111
112static void enter_guest(struct kvm_vcpu *vcpu)
113{
114 struct ucall uc;
115
116 while (true) {
117 vcpu_run(vcpu);
118 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
119
120 switch (get_ucall(vcpu, &uc)) {
121 case UCALL_PR_MSR:
122 pr_msr(&uc);
123 break;
124 case UCALL_PR_HCALL:
125 pr_hcall(&uc);
126 break;
127 case UCALL_ABORT:
128 REPORT_GUEST_ASSERT(uc);
129 return;
130 case UCALL_DONE:
131 return;
132 }
133 }
134}
135
136static void test_pv_unhalt(void)
137{
138 struct kvm_vcpu *vcpu;
139 struct kvm_vm *vm;
140 struct kvm_cpuid_entry2 *ent;
141 u32 kvm_sig_old;
142 int r;
143
144 if (!(kvm_check_cap(KVM_CAP_X86_DISABLE_EXITS) & KVM_X86_DISABLE_EXITS_HLT))
145 return;
146
147 pr_info("testing KVM_FEATURE_PV_UNHALT\n");
148
149 /* KVM_PV_UNHALT test */
150 vm = vm_create_with_one_vcpu(&vcpu, guest_main);
151 vcpu_set_cpuid_feature(vcpu, X86_FEATURE_KVM_PV_UNHALT);
152
153 TEST_ASSERT(vcpu_cpuid_has(vcpu, X86_FEATURE_KVM_PV_UNHALT),
154 "Enabling X86_FEATURE_KVM_PV_UNHALT had no effect");
155
156 /* Verify KVM disallows disabling exits after vCPU creation. */
157 r = __vm_enable_cap(vm, KVM_CAP_X86_DISABLE_EXITS, KVM_X86_DISABLE_EXITS_HLT);
158 TEST_ASSERT(r && errno == EINVAL,
159 "Disabling exits after vCPU creation didn't fail as expected");
160
161 kvm_vm_free(vm);
162
163 /* Verify that KVM clear PV_UNHALT from guest CPUID. */
164 vm = vm_create(1);
165 vm_enable_cap(vm, KVM_CAP_X86_DISABLE_EXITS, KVM_X86_DISABLE_EXITS_HLT);
166
167 vcpu = vm_vcpu_add(vm, 0, NULL);
168 TEST_ASSERT(!vcpu_cpuid_has(vcpu, X86_FEATURE_KVM_PV_UNHALT),
169 "vCPU created with PV_UNHALT set by default");
170
171 vcpu_set_cpuid_feature(vcpu, X86_FEATURE_KVM_PV_UNHALT);
172 TEST_ASSERT(!vcpu_cpuid_has(vcpu, X86_FEATURE_KVM_PV_UNHALT),
173 "PV_UNHALT set in guest CPUID when HLT-exiting is disabled");
174
175 /*
176 * Clobber the KVM PV signature and verify KVM does NOT clear PV_UNHALT
177 * when KVM PV is not present, and DOES clear PV_UNHALT when switching
178 * back to the correct signature..
179 */
180 ent = vcpu_get_cpuid_entry(vcpu, KVM_CPUID_SIGNATURE);
181 kvm_sig_old = ent->ebx;
182 ent->ebx = 0xdeadbeef;
183 vcpu_set_cpuid(vcpu);
184
185 vcpu_set_cpuid_feature(vcpu, X86_FEATURE_KVM_PV_UNHALT);
186 TEST_ASSERT(vcpu_cpuid_has(vcpu, X86_FEATURE_KVM_PV_UNHALT),
187 "PV_UNHALT cleared when using bogus KVM PV signature");
188
189 ent = vcpu_get_cpuid_entry(vcpu, KVM_CPUID_SIGNATURE);
190 ent->ebx = kvm_sig_old;
191 vcpu_set_cpuid(vcpu);
192
193 TEST_ASSERT(!vcpu_cpuid_has(vcpu, X86_FEATURE_KVM_PV_UNHALT),
194 "PV_UNHALT set in guest CPUID when HLT-exiting is disabled");
195
196 /* FIXME: actually test KVM_FEATURE_PV_UNHALT feature */
197
198 kvm_vm_free(vm);
199}
200
201int main(void)
202{
203 struct kvm_vcpu *vcpu;
204 struct kvm_vm *vm;
205
206 TEST_REQUIRE(kvm_has_cap(KVM_CAP_ENFORCE_PV_FEATURE_CPUID));
207
208 vm = vm_create_with_one_vcpu(&vcpu, guest_main);
209
210 vcpu_enable_cap(vcpu, KVM_CAP_ENFORCE_PV_FEATURE_CPUID, 1);
211
212 vcpu_clear_cpuid_entry(vcpu, KVM_CPUID_FEATURES);
213
214 enter_guest(vcpu);
215 kvm_vm_free(vm);
216
217 test_pv_unhalt();
218}