From e67bd7df28a0f2193512184e24a2de4bfd77c69e Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Thu, 3 Feb 2022 11:46:20 +0100 Subject: 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 Message-Id: <20220203104620.277031-7-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/include/x86_64/svm_util.h | 1 + .../testing/selftests/kvm/x86_64/hyperv_svm_test.c | 175 +++++++++++++++++++++ 3 files changed, 177 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c (limited to 'tools') diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 0e4926bc9a58..a1ce7dd40e3e 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -51,6 +51,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/emulator_error_test TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid TEST_GEN_PROGS_x86_64 += x86_64/hyperv_features +TEST_GEN_PROGS_x86_64 += x86_64/hyperv_svm_test TEST_GEN_PROGS_x86_64 += x86_64/kvm_clock_test TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test diff --git a/tools/testing/selftests/kvm/include/x86_64/svm_util.h b/tools/testing/selftests/kvm/include/x86_64/svm_util.h index e23c8a3e8a66..a25aabd8f5e7 100644 --- a/tools/testing/selftests/kvm/include/x86_64/svm_util.h +++ b/tools/testing/selftests/kvm/include/x86_64/svm_util.h @@ -16,6 +16,7 @@ #define CPUID_SVM_BIT 2 #define CPUID_SVM BIT_ULL(CPUID_SVM_BIT) +#define SVM_EXIT_MSR 0x07c #define SVM_EXIT_VMMCALL 0x081 struct svm_test_data { diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c new file mode 100644 index 000000000000..21f5ca9197da --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c @@ -0,0 +1,175 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * KVM_GET/SET_* tests + * + * Copyright (C) 2022, Red Hat, Inc. + * + * Tests for Hyper-V extensions to SVM. + */ +#define _GNU_SOURCE /* for program_invocation_short_name */ +#include +#include +#include +#include +#include +#include + +#include "test_util.h" + +#include "kvm_util.h" +#include "processor.h" +#include "svm_util.h" +#include "hyperv.h" + +#define VCPU_ID 1 +#define L2_GUEST_STACK_SIZE 256 + +struct hv_enlightenments { + struct __packed hv_enlightenments_control { + u32 nested_flush_hypercall:1; + u32 msr_bitmap:1; + u32 enlightened_npt_tlb: 1; + u32 reserved:29; + } __packed hv_enlightenments_control; + u32 hv_vp_id; + u64 hv_vm_id; + u64 partition_assist_page; + u64 reserved; +} __packed; + +/* + * Hyper-V uses the software reserved clean bit in VMCB + */ +#define VMCB_HV_NESTED_ENLIGHTENMENTS (1U << 31) + +static inline void vmmcall(void) +{ + __asm__ __volatile__("vmmcall"); +} + +void l2_guest_code(void) +{ + GUEST_SYNC(3); + /* Exit to L1 */ + vmmcall(); + + /* MSR-Bitmap tests */ + rdmsr(MSR_FS_BASE); /* intercepted */ + rdmsr(MSR_FS_BASE); /* intercepted */ + rdmsr(MSR_GS_BASE); /* not intercepted */ + vmmcall(); + rdmsr(MSR_GS_BASE); /* intercepted */ + + GUEST_SYNC(5); + + /* Done, exit to L1 and never come back. */ + vmmcall(); +} + +static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm) +{ + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + struct vmcb *vmcb = svm->vmcb; + struct hv_enlightenments *hve = + (struct hv_enlightenments *)vmcb->control.reserved_sw; + + GUEST_SYNC(1); + + wrmsr(HV_X64_MSR_GUEST_OS_ID, (u64)0x8100 << 48); + + GUEST_ASSERT(svm->vmcb_gpa); + /* Prepare for L2 execution. */ + generic_svm_setup(svm, l2_guest_code, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + GUEST_SYNC(2); + run_guest(vmcb, svm->vmcb_gpa); + GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL); + GUEST_SYNC(4); + vmcb->save.rip += 3; + + /* Intercept RDMSR 0xc0000100 */ + vmcb->control.intercept |= 1ULL << INTERCEPT_MSR_PROT; + set_bit(2 * (MSR_FS_BASE & 0x1fff), svm->msr + 0x800); + run_guest(vmcb, svm->vmcb_gpa); + GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR); + vmcb->save.rip += 2; /* rdmsr */ + + /* Enable enlightened MSR bitmap */ + hve->hv_enlightenments_control.msr_bitmap = 1; + run_guest(vmcb, svm->vmcb_gpa); + GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR); + vmcb->save.rip += 2; /* rdmsr */ + + /* Intercept RDMSR 0xc0000101 without telling KVM about it */ + set_bit(2 * (MSR_GS_BASE & 0x1fff), svm->msr + 0x800); + /* Make sure HV_VMX_ENLIGHTENED_CLEAN_FIELD_MSR_BITMAP is set */ + vmcb->control.clean |= VMCB_HV_NESTED_ENLIGHTENMENTS; + run_guest(vmcb, svm->vmcb_gpa); + /* Make sure we don't see SVM_EXIT_MSR here so eMSR bitmap works */ + GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL); + vmcb->save.rip += 3; /* vmcall */ + + /* Now tell KVM we've changed MSR-Bitmap */ + vmcb->control.clean &= ~VMCB_HV_NESTED_ENLIGHTENMENTS; + run_guest(vmcb, svm->vmcb_gpa); + GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR); + vmcb->save.rip += 2; /* rdmsr */ + + run_guest(vmcb, svm->vmcb_gpa); + GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL); + GUEST_SYNC(6); + + GUEST_DONE(); +} + +int main(int argc, char *argv[]) +{ + vm_vaddr_t nested_gva = 0; + + struct kvm_vm *vm; + struct kvm_run *run; + struct ucall uc; + int stage; + + if (!nested_svm_supported()) { + print_skip("Nested SVM not supported"); + exit(KSFT_SKIP); + } + /* Create VM */ + vm = vm_create_default(VCPU_ID, 0, guest_code); + vcpu_set_hv_cpuid(vm, VCPU_ID); + run = vcpu_state(vm, VCPU_ID); + vcpu_alloc_svm(vm, &nested_gva); + vcpu_args_set(vm, VCPU_ID, 1, nested_gva); + + for (stage = 1;; stage++) { + _vcpu_run(vm, VCPU_ID); + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, + "Stage %d: unexpected exit reason: %u (%s),\n", + stage, run->exit_reason, + exit_reason_str(run->exit_reason)); + + switch (get_ucall(vm, VCPU_ID, &uc)) { + case UCALL_ABORT: + TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0], + __FILE__, uc.args[1]); + /* NOT REACHED */ + case UCALL_SYNC: + break; + case UCALL_DONE: + goto done; + default: + TEST_FAIL("Unknown ucall %lu", uc.cmd); + } + + /* UCALL_SYNC is handled here. */ + TEST_ASSERT(!strcmp((const char *)uc.args[0], "hello") && + uc.args[1] == stage, "Stage %d: Unexpected register values vmexit, got %lx", + stage, (ulong)uc.args[1]); + + } + +done: + kvm_vm_free(vm); +} -- cgit v1.2.3