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KVM: selftests: nSVM: Add enlightened MSR-Bitmap selftest
Introduce a new test for Hyper-V nSVM extensions (Hyper-V on KVM) and add a test for enlightened MSR-Bitmap feature: - Intercept access to MSR_FS_BASE in L1 and check that this works with enlightened MSR-Bitmap disabled. - Enabled enlightened MSR-Bitmap and check that the intercept still works as expected. - Intercept access to MSR_GS_BASE but don't clear the corresponding bit from clean fields mask, KVM is supposed to skip updating MSR-Bitmap02 and thus the consequent access to the MSR from L2 will not get intercepted. - Finally, clear the corresponding bit from clean fields mask and check that access to MSR_GS_BASE is now intercepted. The test works with the assumption, that access to MSR_FS_BASE/MSR_GS_BASE is not intercepted for L1. If this ever becomes not true the test will fail as nested_svm_exit_handled_msr() always checks L1's MSR-Bitmap for L2 irrespective of clean fields. The behavior is correct as enlightened MSR-Bitmap feature is just an optimization, KVM is not obliged to ignore updates when the corresponding bit in clean fields stays clear. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220203104620.277031-7-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -51,6 +51,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/emulator_error_test
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TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock
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TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
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TEST_GEN_PROGS_x86_64 += x86_64/hyperv_features
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TEST_GEN_PROGS_x86_64 += x86_64/hyperv_svm_test
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TEST_GEN_PROGS_x86_64 += x86_64/kvm_clock_test
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TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
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TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test
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@ -16,6 +16,7 @@
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#define CPUID_SVM_BIT 2
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#define CPUID_SVM BIT_ULL(CPUID_SVM_BIT)
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#define SVM_EXIT_MSR 0x07c
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#define SVM_EXIT_VMMCALL 0x081
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struct svm_test_data {
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175
tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
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175
tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
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@ -0,0 +1,175 @@
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* KVM_GET/SET_* tests
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*
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* Copyright (C) 2022, Red Hat, Inc.
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*
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* Tests for Hyper-V extensions to SVM.
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*/
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#define _GNU_SOURCE /* for program_invocation_short_name */
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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 <linux/bitmap.h>
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#include "test_util.h"
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#include "kvm_util.h"
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#include "processor.h"
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#include "svm_util.h"
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#include "hyperv.h"
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#define VCPU_ID 1
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#define L2_GUEST_STACK_SIZE 256
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struct hv_enlightenments {
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struct __packed hv_enlightenments_control {
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u32 nested_flush_hypercall:1;
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u32 msr_bitmap:1;
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u32 enlightened_npt_tlb: 1;
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u32 reserved:29;
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} __packed hv_enlightenments_control;
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u32 hv_vp_id;
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u64 hv_vm_id;
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u64 partition_assist_page;
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u64 reserved;
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} __packed;
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/*
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* Hyper-V uses the software reserved clean bit in VMCB
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*/
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#define VMCB_HV_NESTED_ENLIGHTENMENTS (1U << 31)
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static inline void vmmcall(void)
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{
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__asm__ __volatile__("vmmcall");
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}
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void l2_guest_code(void)
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{
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GUEST_SYNC(3);
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/* Exit to L1 */
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vmmcall();
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/* MSR-Bitmap tests */
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rdmsr(MSR_FS_BASE); /* intercepted */
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rdmsr(MSR_FS_BASE); /* intercepted */
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rdmsr(MSR_GS_BASE); /* not intercepted */
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vmmcall();
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rdmsr(MSR_GS_BASE); /* intercepted */
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GUEST_SYNC(5);
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/* Done, exit to L1 and never come back. */
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vmmcall();
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}
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static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
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{
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unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
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struct vmcb *vmcb = svm->vmcb;
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struct hv_enlightenments *hve =
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(struct hv_enlightenments *)vmcb->control.reserved_sw;
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GUEST_SYNC(1);
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wrmsr(HV_X64_MSR_GUEST_OS_ID, (u64)0x8100 << 48);
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GUEST_ASSERT(svm->vmcb_gpa);
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/* Prepare for L2 execution. */
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generic_svm_setup(svm, l2_guest_code,
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&l2_guest_stack[L2_GUEST_STACK_SIZE]);
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GUEST_SYNC(2);
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run_guest(vmcb, svm->vmcb_gpa);
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GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
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GUEST_SYNC(4);
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vmcb->save.rip += 3;
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/* Intercept RDMSR 0xc0000100 */
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vmcb->control.intercept |= 1ULL << INTERCEPT_MSR_PROT;
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set_bit(2 * (MSR_FS_BASE & 0x1fff), svm->msr + 0x800);
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run_guest(vmcb, svm->vmcb_gpa);
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GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR);
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vmcb->save.rip += 2; /* rdmsr */
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/* Enable enlightened MSR bitmap */
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hve->hv_enlightenments_control.msr_bitmap = 1;
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run_guest(vmcb, svm->vmcb_gpa);
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GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR);
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vmcb->save.rip += 2; /* rdmsr */
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/* Intercept RDMSR 0xc0000101 without telling KVM about it */
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set_bit(2 * (MSR_GS_BASE & 0x1fff), svm->msr + 0x800);
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/* Make sure HV_VMX_ENLIGHTENED_CLEAN_FIELD_MSR_BITMAP is set */
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vmcb->control.clean |= VMCB_HV_NESTED_ENLIGHTENMENTS;
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run_guest(vmcb, svm->vmcb_gpa);
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/* Make sure we don't see SVM_EXIT_MSR here so eMSR bitmap works */
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GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
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vmcb->save.rip += 3; /* vmcall */
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/* Now tell KVM we've changed MSR-Bitmap */
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vmcb->control.clean &= ~VMCB_HV_NESTED_ENLIGHTENMENTS;
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run_guest(vmcb, svm->vmcb_gpa);
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GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR);
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vmcb->save.rip += 2; /* rdmsr */
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run_guest(vmcb, svm->vmcb_gpa);
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GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
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GUEST_SYNC(6);
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GUEST_DONE();
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}
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int main(int argc, char *argv[])
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{
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vm_vaddr_t nested_gva = 0;
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struct kvm_vm *vm;
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struct kvm_run *run;
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struct ucall uc;
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int stage;
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if (!nested_svm_supported()) {
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print_skip("Nested SVM not supported");
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exit(KSFT_SKIP);
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}
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/* Create VM */
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vm = vm_create_default(VCPU_ID, 0, guest_code);
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vcpu_set_hv_cpuid(vm, VCPU_ID);
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run = vcpu_state(vm, VCPU_ID);
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vcpu_alloc_svm(vm, &nested_gva);
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vcpu_args_set(vm, VCPU_ID, 1, nested_gva);
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for (stage = 1;; stage++) {
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_vcpu_run(vm, VCPU_ID);
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TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
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"Stage %d: unexpected exit reason: %u (%s),\n",
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stage, run->exit_reason,
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exit_reason_str(run->exit_reason));
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switch (get_ucall(vm, VCPU_ID, &uc)) {
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case UCALL_ABORT:
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TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
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__FILE__, uc.args[1]);
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/* NOT REACHED */
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case UCALL_SYNC:
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break;
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case UCALL_DONE:
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goto done;
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default:
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TEST_FAIL("Unknown ucall %lu", uc.cmd);
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}
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/* UCALL_SYNC is handled here. */
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TEST_ASSERT(!strcmp((const char *)uc.args[0], "hello") &&
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uc.args[1] == stage, "Stage %d: Unexpected register values vmexit, got %lx",
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stage, (ulong)uc.args[1]);
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}
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done:
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kvm_vm_free(vm);
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}
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