ca35906688
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 c4d2188206ba ("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>
130 lines
2.5 KiB
C
130 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* CR4 and CPUID sync test
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*
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* Copyright 2018, Red Hat, Inc. and/or its affiliates.
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*
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* Author:
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* Wei Huang <wei@redhat.com>
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*/
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include "test_util.h"
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#include "kvm_util.h"
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#include "x86.h"
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#define X86_FEATURE_XSAVE (1<<26)
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#define X86_FEATURE_OSXSAVE (1<<27)
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#define VCPU_ID 1
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enum {
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GUEST_UPDATE_CR4 = 0x1000,
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GUEST_FAILED,
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GUEST_DONE,
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};
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static void exit_to_hv(uint16_t port)
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{
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__asm__ __volatile__("in %[port], %%al"
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:
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: [port]"d"(port)
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: "rax");
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}
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static inline bool cr4_cpuid_is_sync(void)
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{
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int func, subfunc;
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uint32_t eax, ebx, ecx, edx;
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uint64_t cr4;
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func = 0x1;
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subfunc = 0x0;
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__asm__ __volatile__("cpuid"
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: "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx)
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: "a"(func), "c"(subfunc));
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cr4 = get_cr4();
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return (!!(ecx & X86_FEATURE_OSXSAVE)) == (!!(cr4 & X86_CR4_OSXSAVE));
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}
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static void guest_code(void)
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{
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uint64_t cr4;
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/* turn on CR4.OSXSAVE */
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cr4 = get_cr4();
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cr4 |= X86_CR4_OSXSAVE;
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set_cr4(cr4);
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/* verify CR4.OSXSAVE == CPUID.OSXSAVE */
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if (!cr4_cpuid_is_sync())
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exit_to_hv(GUEST_FAILED);
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/* notify hypervisor to change CR4 */
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exit_to_hv(GUEST_UPDATE_CR4);
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/* check again */
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if (!cr4_cpuid_is_sync())
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exit_to_hv(GUEST_FAILED);
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exit_to_hv(GUEST_DONE);
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}
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int main(int argc, char *argv[])
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{
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struct kvm_run *run;
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struct kvm_vm *vm;
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struct kvm_sregs sregs;
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struct kvm_cpuid_entry2 *entry;
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int rc;
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entry = kvm_get_supported_cpuid_entry(1);
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if (!(entry->ecx & X86_FEATURE_XSAVE)) {
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printf("XSAVE feature not supported, skipping test\n");
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return 0;
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}
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/* Tell stdout not to buffer its content */
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setbuf(stdout, NULL);
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/* Create VM */
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vm = vm_create_default(VCPU_ID, guest_code);
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vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
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run = vcpu_state(vm, VCPU_ID);
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while (1) {
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rc = _vcpu_run(vm, VCPU_ID);
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if (run->exit_reason == KVM_EXIT_IO) {
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switch (run->io.port) {
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case GUEST_UPDATE_CR4:
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/* emulate hypervisor clearing CR4.OSXSAVE */
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vcpu_sregs_get(vm, VCPU_ID, &sregs);
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sregs.cr4 &= ~X86_CR4_OSXSAVE;
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vcpu_sregs_set(vm, VCPU_ID, &sregs);
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break;
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case GUEST_FAILED:
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TEST_ASSERT(false, "Guest CR4 bit (OSXSAVE) unsynchronized with CPUID bit.");
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break;
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case GUEST_DONE:
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goto done;
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default:
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TEST_ASSERT(false, "Unknown port 0x%x.",
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run->io.port);
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}
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}
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}
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kvm_vm_free(vm);
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done:
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return 0;
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}
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