From 6c2fa8b20d0cad3719b024ba0f25a50199a90c9a Mon Sep 17 00:00:00 2001 From: Oliver Upton Date: Wed, 16 Mar 2022 00:55:38 +0000 Subject: selftests: KVM: Test KVM_X86_QUIRK_FIX_HYPERCALL_INSN Add a test that asserts KVM rewrites guest hypercall instructions to match the running architecture (VMCALL on VMX, VMMCALL on SVM). Additionally, test that with the quirk disabled, KVM no longer rewrites guest instructions and instead injects a #UD. Signed-off-by: Oliver Upton Message-Id: <20220316005538.2282772-3-oupton@google.com> Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/x86_64/fix_hypercall_test.c | 170 +++++++++++++++++++++ 3 files changed, 172 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c (limited to 'tools/testing/selftests') diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index 9b67343dc4ab..1f1b6c978bf7 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -15,6 +15,7 @@ /x86_64/debug_regs /x86_64/evmcs_test /x86_64/emulator_error_test +/x86_64/fix_hypercall_test /x86_64/get_msr_index_features /x86_64/kvm_clock_test /x86_64/kvm_pv_test diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 04099f453b59..03662666b30d 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -48,6 +48,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/cr4_cpuid_sync_test TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features TEST_GEN_PROGS_x86_64 += x86_64/evmcs_test TEST_GEN_PROGS_x86_64 += x86_64/emulator_error_test +TEST_GEN_PROGS_x86_64 += x86_64/fix_hypercall_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 diff --git a/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c b/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c new file mode 100644 index 000000000000..1f5c32146f3d --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c @@ -0,0 +1,170 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020, Google LLC. + * + * Tests for KVM paravirtual feature disablement + */ +#include +#include +#include +#include + +#include "apic.h" +#include "test_util.h" +#include "kvm_util.h" +#include "processor.h" + +#define VCPU_ID 0 + +static bool ud_expected; + +static void guest_ud_handler(struct ex_regs *regs) +{ + GUEST_ASSERT(ud_expected); + GUEST_DONE(); +} + +extern unsigned char svm_hypercall_insn; +static uint64_t svm_do_sched_yield(uint8_t apic_id) +{ + uint64_t ret; + + asm volatile("mov %1, %%rax\n\t" + "mov %2, %%rbx\n\t" + "svm_hypercall_insn:\n\t" + "vmmcall\n\t" + "mov %%rax, %0\n\t" + : "=r"(ret) + : "r"((uint64_t)KVM_HC_SCHED_YIELD), "r"((uint64_t)apic_id) + : "rax", "rbx", "memory"); + + return ret; +} + +extern unsigned char vmx_hypercall_insn; +static uint64_t vmx_do_sched_yield(uint8_t apic_id) +{ + uint64_t ret; + + asm volatile("mov %1, %%rax\n\t" + "mov %2, %%rbx\n\t" + "vmx_hypercall_insn:\n\t" + "vmcall\n\t" + "mov %%rax, %0\n\t" + : "=r"(ret) + : "r"((uint64_t)KVM_HC_SCHED_YIELD), "r"((uint64_t)apic_id) + : "rax", "rbx", "memory"); + + return ret; +} + +static void assert_hypercall_insn(unsigned char *exp_insn, unsigned char *obs_insn) +{ + uint32_t exp = 0, obs = 0; + + memcpy(&exp, exp_insn, sizeof(exp)); + memcpy(&obs, obs_insn, sizeof(obs)); + + GUEST_ASSERT_EQ(exp, obs); +} + +static void guest_main(void) +{ + unsigned char *native_hypercall_insn, *hypercall_insn; + uint8_t apic_id; + + apic_id = GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID)); + + if (is_intel_cpu()) { + native_hypercall_insn = &vmx_hypercall_insn; + hypercall_insn = &svm_hypercall_insn; + svm_do_sched_yield(apic_id); + } else if (is_amd_cpu()) { + native_hypercall_insn = &svm_hypercall_insn; + hypercall_insn = &vmx_hypercall_insn; + vmx_do_sched_yield(apic_id); + } else { + GUEST_ASSERT(0); + /* unreachable */ + return; + } + + GUEST_ASSERT(!ud_expected); + assert_hypercall_insn(native_hypercall_insn, hypercall_insn); + GUEST_DONE(); +} + +static void setup_ud_vector(struct kvm_vm *vm) +{ + vm_init_descriptor_tables(vm); + vcpu_init_descriptor_tables(vm, VCPU_ID); + vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler); +} + +static void enter_guest(struct kvm_vm *vm) +{ + struct kvm_run *run; + struct ucall uc; + + run = vcpu_state(vm, VCPU_ID); + + vcpu_run(vm, VCPU_ID); + switch (get_ucall(vm, VCPU_ID, &uc)) { + case UCALL_SYNC: + pr_info("%s: %016lx\n", (const char *)uc.args[2], uc.args[3]); + break; + case UCALL_DONE: + return; + case UCALL_ABORT: + TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0], __FILE__, uc.args[1]); + default: + TEST_FAIL("Unhandled ucall: %ld\nexit_reason: %u (%s)", + uc.cmd, run->exit_reason, exit_reason_str(run->exit_reason)); + } +} + +static void test_fix_hypercall(void) +{ + struct kvm_vm *vm; + + vm = vm_create_default(VCPU_ID, 0, guest_main); + setup_ud_vector(vm); + + ud_expected = false; + sync_global_to_guest(vm, ud_expected); + + virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA); + + enter_guest(vm); +} + +static void test_fix_hypercall_disabled(void) +{ + struct kvm_enable_cap cap = {0}; + struct kvm_vm *vm; + + vm = vm_create_default(VCPU_ID, 0, guest_main); + setup_ud_vector(vm); + + cap.cap = KVM_CAP_DISABLE_QUIRKS2; + cap.args[0] = KVM_X86_QUIRK_FIX_HYPERCALL_INSN; + vm_enable_cap(vm, &cap); + + ud_expected = true; + sync_global_to_guest(vm, ud_expected); + + virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA); + + enter_guest(vm); +} + +int main(void) +{ + if (!(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & KVM_X86_QUIRK_FIX_HYPERCALL_INSN)) { + print_skip("KVM_X86_QUIRK_HYPERCALL_INSN not supported"); + exit(KSFT_SKIP); + } + + test_fix_hypercall(); + test_fix_hypercall_disabled(); +} -- cgit