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 --- tools/testing/selftests/kvm/Makefile | 1 + tools/testing/selftests/kvm/cr4_cpuid_sync_test.c | 129 ++++++++++++++++++++++ 2 files changed, 130 insertions(+) create mode 100644 tools/testing/selftests/kvm/cr4_cpuid_sync_test.c
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index d9d0031..65bda4f 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -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)) diff --git a/tools/testing/selftests/kvm/cr4_cpuid_sync_test.c b/tools/testing/selftests/kvm/cr4_cpuid_sync_test.c new file mode 100644 index 0000000..dbbaf3c --- /dev/null +++ b/tools/testing/selftests/kvm/cr4_cpuid_sync_test.c @@ -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_vmx(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; +}
On 26/06/2018 05:41, Wei Huang wrote:
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
tools/testing/selftests/kvm/Makefile | 1 + tools/testing/selftests/kvm/cr4_cpuid_sync_test.c | 129 ++++++++++++++++++++++ 2 files changed, 130 insertions(+) create mode 100644 tools/testing/selftests/kvm/cr4_cpuid_sync_test.c
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index d9d0031..65bda4f 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -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)) diff --git a/tools/testing/selftests/kvm/cr4_cpuid_sync_test.c b/tools/testing/selftests/kvm/cr4_cpuid_sync_test.c new file mode 100644 index 0000000..dbbaf3c --- /dev/null +++ b/tools/testing/selftests/kvm/cr4_cpuid_sync_test.c @@ -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_vmx(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;
+}
Queued, thanks.
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