diff options
Diffstat (limited to 'tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c')
-rw-r--r-- | tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c | 135 |
1 files changed, 135 insertions, 0 deletions
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 0000000000..0f728f05ea --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c @@ -0,0 +1,135 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020, Google LLC. + * + * Tests for KVM paravirtual feature disablement + */ +#include <asm/kvm_para.h> +#include <linux/kvm_para.h> +#include <linux/stringify.h> +#include <stdint.h> + +#include "apic.h" +#include "test_util.h" +#include "kvm_util.h" +#include "processor.h" + +/* VMCALL and VMMCALL are both 3-byte opcodes. */ +#define HYPERCALL_INSN_SIZE 3 + +static bool quirk_disabled; + +static void guest_ud_handler(struct ex_regs *regs) +{ + regs->rax = -EFAULT; + regs->rip += HYPERCALL_INSN_SIZE; +} + +static const uint8_t vmx_vmcall[HYPERCALL_INSN_SIZE] = { 0x0f, 0x01, 0xc1 }; +static const uint8_t svm_vmmcall[HYPERCALL_INSN_SIZE] = { 0x0f, 0x01, 0xd9 }; + +extern uint8_t hypercall_insn[HYPERCALL_INSN_SIZE]; +static uint64_t do_sched_yield(uint8_t apic_id) +{ + uint64_t ret; + + asm volatile("hypercall_insn:\n\t" + ".byte 0xcc,0xcc,0xcc\n\t" + : "=a"(ret) + : "a"((uint64_t)KVM_HC_SCHED_YIELD), "b"((uint64_t)apic_id) + : "memory"); + + return ret; +} + +static void guest_main(void) +{ + const uint8_t *native_hypercall_insn; + const uint8_t *other_hypercall_insn; + uint64_t ret; + + if (host_cpu_is_intel) { + native_hypercall_insn = vmx_vmcall; + other_hypercall_insn = svm_vmmcall; + } else if (host_cpu_is_amd) { + native_hypercall_insn = svm_vmmcall; + other_hypercall_insn = vmx_vmcall; + } else { + GUEST_ASSERT(0); + /* unreachable */ + return; + } + + memcpy(hypercall_insn, other_hypercall_insn, HYPERCALL_INSN_SIZE); + + ret = do_sched_yield(GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID))); + + /* + * If the quirk is disabled, verify that guest_ud_handler() "returned" + * -EFAULT and that KVM did NOT patch the hypercall. If the quirk is + * enabled, verify that the hypercall succeeded and that KVM patched in + * the "right" hypercall. + */ + if (quirk_disabled) { + GUEST_ASSERT(ret == (uint64_t)-EFAULT); + GUEST_ASSERT(!memcmp(other_hypercall_insn, hypercall_insn, + HYPERCALL_INSN_SIZE)); + } else { + GUEST_ASSERT(!ret); + GUEST_ASSERT(!memcmp(native_hypercall_insn, hypercall_insn, + HYPERCALL_INSN_SIZE)); + } + + GUEST_DONE(); +} + +static void enter_guest(struct kvm_vcpu *vcpu) +{ + struct kvm_run *run = vcpu->run; + struct ucall uc; + + vcpu_run(vcpu); + switch (get_ucall(vcpu, &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: + REPORT_GUEST_ASSERT(uc); + 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(bool disable_quirk) +{ + struct kvm_vcpu *vcpu; + struct kvm_vm *vm; + + vm = vm_create_with_one_vcpu(&vcpu, guest_main); + + vm_init_descriptor_tables(vcpu->vm); + vcpu_init_descriptor_tables(vcpu); + vm_install_exception_handler(vcpu->vm, UD_VECTOR, guest_ud_handler); + + if (disable_quirk) + vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, + KVM_X86_QUIRK_FIX_HYPERCALL_INSN); + + quirk_disabled = disable_quirk; + sync_global_to_guest(vm, quirk_disabled); + + virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA); + + enter_guest(vcpu); +} + +int main(void) +{ + TEST_REQUIRE(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & KVM_X86_QUIRK_FIX_HYPERCALL_INSN); + + test_fix_hypercall(false); + test_fix_hypercall(true); +} |