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kvm: selftests: add cr4_cpuid_sync_test

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KVM is supposed to update some guest VM's CPUID bits (e.g. OSXSAVE) when
CR4 is changed. A bug was found in KVM recently and it was fixed by
Commit c4d2188206 ("KVM: x86: Update cpuid properly when CR4.OSXAVE or
CR4.PKE is changed"). This patch adds a test to verify the synchronization
between guest VM's CR4 and CPUID bits.

Signed-off-by: Wei Huang <wei@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Wei Huang 2018-06-25 23:41:57 -04:00 committed by Paolo Bonzini
parent d2ce98ca0a
commit ca35906688
3 changed files with 131 additions and 0 deletions
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1
tools/testing/selftests/kvm/.gitignore vendored
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@ -1,3 +1,4 @@
cr4_cpuid_sync_test
set_sregs_test
sync_regs_test
vmx_tsc_adjust_test

1
tools/testing/selftests/kvm/Makefile
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@ -9,6 +9,7 @@ LIBKVM_x86_64 = lib/x86.c lib/vmx.c
TEST_GEN_PROGS_x86_64 = set_sregs_test
TEST_GEN_PROGS_x86_64 += sync_regs_test
TEST_GEN_PROGS_x86_64 += vmx_tsc_adjust_test
TEST_GEN_PROGS_x86_64 += cr4_cpuid_sync_test
TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
LIBKVM += $(LIBKVM_$(UNAME_M))

129
tools/testing/selftests/kvm/cr4_cpuid_sync_test.c Normal file
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@ -0,0 +1,129 @@
// SPDX-License-Identifier: GPL-2.0
/*
* CR4 and CPUID sync test
*
* Copyright 2018, Red Hat, Inc. and/or its affiliates.
*
* Author:
* Wei Huang <wei@redhat.com>
*/
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include "test_util.h"
#include "kvm_util.h"
#include "x86.h"
#define X86_FEATURE_XSAVE (1<<26)
#define X86_FEATURE_OSXSAVE (1<<27)
#define VCPU_ID 1
enum {
GUEST_UPDATE_CR4 = 0x1000,
GUEST_FAILED,
GUEST_DONE,
};
static void exit_to_hv(uint16_t port)
{
__asm__ __volatile__("in %[port], %%al"
:
: [port]"d"(port)
: "rax");
}
static inline bool cr4_cpuid_is_sync(void)
{
int func, subfunc;
uint32_t eax, ebx, ecx, edx;
uint64_t cr4;
func = 0x1;
subfunc = 0x0;
__asm__ __volatile__("cpuid"
: "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx)
: "a"(func), "c"(subfunc));
cr4 = get_cr4();
return (!!(ecx & X86_FEATURE_OSXSAVE)) == (!!(cr4 & X86_CR4_OSXSAVE));
}
static void guest_code(void)
{
uint64_t cr4;
/* turn on CR4.OSXSAVE */
cr4 = get_cr4();
cr4 |= X86_CR4_OSXSAVE;
set_cr4(cr4);
/* verify CR4.OSXSAVE == CPUID.OSXSAVE */
if (!cr4_cpuid_is_sync())
exit_to_hv(GUEST_FAILED);
/* notify hypervisor to change CR4 */
exit_to_hv(GUEST_UPDATE_CR4);
/* check again */
if (!cr4_cpuid_is_sync())
exit_to_hv(GUEST_FAILED);
exit_to_hv(GUEST_DONE);
}
int main(int argc, char *argv[])
{
struct kvm_run *run;
struct kvm_vm *vm;
struct kvm_sregs sregs;
struct kvm_cpuid_entry2 *entry;
int rc;
entry = kvm_get_supported_cpuid_entry(1);
if (!(entry->ecx & X86_FEATURE_XSAVE)) {
printf("XSAVE feature not supported, skipping test\n");
return 0;
}
/* Tell stdout not to buffer its content */
setbuf(stdout, NULL);
/* Create VM */
vm = vm_create_default(VCPU_ID, guest_code);
vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
run = vcpu_state(vm, VCPU_ID);
while (1) {
rc = _vcpu_run(vm, VCPU_ID);
if (run->exit_reason == KVM_EXIT_IO) {
switch (run->io.port) {
case GUEST_UPDATE_CR4:
/* emulate hypervisor clearing CR4.OSXSAVE */
vcpu_sregs_get(vm, VCPU_ID, &sregs);
sregs.cr4 &= ~X86_CR4_OSXSAVE;
vcpu_sregs_set(vm, VCPU_ID, &sregs);
break;
case GUEST_FAILED:
TEST_ASSERT(false, "Guest CR4 bit (OSXSAVE) unsynchronized with CPUID bit.");
break;
case GUEST_DONE:
goto done;
default:
TEST_ASSERT(false, "Unknown port 0x%x.",
run->io.port);
}
}
}
kvm_vm_free(vm);
done:
return 0;
}