1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * CR4 and CPUID sync test
4 *
5 * Copyright 2018, Red Hat, Inc. and/or its affiliates.
6 *
7 * Author:
8 * Wei Huang <[email protected]>
9 */
10
11 #include <fcntl.h>
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <sys/ioctl.h>
16
17 #include "test_util.h"
18
19 #include "kvm_util.h"
20 #include "processor.h"
21
22 #define MAGIC_HYPERCALL_PORT 0x80
23
guest_code(void)24 static void guest_code(void)
25 {
26 u32 regs[4] = {
27 [KVM_CPUID_EAX] = X86_FEATURE_OSXSAVE.function,
28 [KVM_CPUID_ECX] = X86_FEATURE_OSXSAVE.index,
29 };
30
31 /* CR4.OSXSAVE should be enabled by default (for selftests vCPUs). */
32 GUEST_ASSERT(get_cr4() & X86_CR4_OSXSAVE);
33
34 /* verify CR4.OSXSAVE == CPUID.OSXSAVE */
35 GUEST_ASSERT(this_cpu_has(X86_FEATURE_OSXSAVE));
36
37 /*
38 * Notify hypervisor to clear CR4.0SXSAVE, do CPUID and save output,
39 * and then restore CR4. Do this all in assembly to ensure no AVX
40 * instructions are executed while OSXSAVE=0.
41 */
42 asm volatile (
43 "out %%al, $" __stringify(MAGIC_HYPERCALL_PORT) "\n\t"
44 "cpuid\n\t"
45 "mov %%rdi, %%cr4\n\t"
46 : "+a" (regs[KVM_CPUID_EAX]),
47 "=b" (regs[KVM_CPUID_EBX]),
48 "+c" (regs[KVM_CPUID_ECX]),
49 "=d" (regs[KVM_CPUID_EDX])
50 : "D" (get_cr4())
51 );
52
53 /* Verify KVM cleared OSXSAVE in CPUID when it was cleared in CR4. */
54 GUEST_ASSERT(!(regs[X86_FEATURE_OSXSAVE.reg] & BIT(X86_FEATURE_OSXSAVE.bit)));
55
56 /* Verify restoring CR4 also restored OSXSAVE in CPUID. */
57 GUEST_ASSERT(this_cpu_has(X86_FEATURE_OSXSAVE));
58
59 GUEST_DONE();
60 }
61
main(int argc,char * argv[])62 int main(int argc, char *argv[])
63 {
64 struct kvm_vcpu *vcpu;
65 struct kvm_vm *vm;
66 struct kvm_sregs sregs;
67 struct ucall uc;
68
69 TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_XSAVE));
70
71 vm = vm_create_with_one_vcpu(&vcpu, guest_code);
72
73 while (1) {
74 vcpu_run(vcpu);
75 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
76
77 if (vcpu->run->io.port == MAGIC_HYPERCALL_PORT &&
78 vcpu->run->io.direction == KVM_EXIT_IO_OUT) {
79 /* emulate hypervisor clearing CR4.OSXSAVE */
80 vcpu_sregs_get(vcpu, &sregs);
81 sregs.cr4 &= ~X86_CR4_OSXSAVE;
82 vcpu_sregs_set(vcpu, &sregs);
83 continue;
84 }
85
86 switch (get_ucall(vcpu, &uc)) {
87 case UCALL_ABORT:
88 REPORT_GUEST_ASSERT(uc);
89 break;
90 case UCALL_DONE:
91 goto done;
92 default:
93 TEST_FAIL("Unknown ucall %lu", uc.cmd);
94 }
95 }
96
97 done:
98 kvm_vm_free(vm);
99 return 0;
100 }
101