136 lines
3.2 KiB
C
136 lines
3.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2020, Google LLC.
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*
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* Tests for KVM paravirtual feature disablement
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*/
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#include <asm/kvm_para.h>
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#include <linux/kvm_para.h>
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#include <linux/stringify.h>
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#include <stdint.h>
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#include "apic.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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/* VMCALL and VMMCALL are both 3-byte opcodes. */
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#define HYPERCALL_INSN_SIZE 3
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static bool quirk_disabled;
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static void guest_ud_handler(struct ex_regs *regs)
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{
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regs->rax = -EFAULT;
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regs->rip += HYPERCALL_INSN_SIZE;
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}
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static const uint8_t vmx_vmcall[HYPERCALL_INSN_SIZE] = { 0x0f, 0x01, 0xc1 };
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static const uint8_t svm_vmmcall[HYPERCALL_INSN_SIZE] = { 0x0f, 0x01, 0xd9 };
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extern uint8_t hypercall_insn[HYPERCALL_INSN_SIZE];
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static uint64_t do_sched_yield(uint8_t apic_id)
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{
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uint64_t ret;
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asm volatile("hypercall_insn:\n\t"
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".byte 0xcc,0xcc,0xcc\n\t"
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: "=a"(ret)
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: "a"((uint64_t)KVM_HC_SCHED_YIELD), "b"((uint64_t)apic_id)
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: "memory");
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return ret;
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}
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static void guest_main(void)
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{
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const uint8_t *native_hypercall_insn;
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const uint8_t *other_hypercall_insn;
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uint64_t ret;
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if (host_cpu_is_intel) {
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native_hypercall_insn = vmx_vmcall;
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other_hypercall_insn = svm_vmmcall;
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} else if (host_cpu_is_amd) {
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native_hypercall_insn = svm_vmmcall;
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other_hypercall_insn = vmx_vmcall;
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} else {
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GUEST_ASSERT(0);
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/* unreachable */
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return;
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}
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memcpy(hypercall_insn, other_hypercall_insn, HYPERCALL_INSN_SIZE);
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ret = do_sched_yield(GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID)));
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/*
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* If the quirk is disabled, verify that guest_ud_handler() "returned"
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* -EFAULT and that KVM did NOT patch the hypercall. If the quirk is
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* enabled, verify that the hypercall succeeded and that KVM patched in
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* the "right" hypercall.
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*/
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if (quirk_disabled) {
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GUEST_ASSERT(ret == (uint64_t)-EFAULT);
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GUEST_ASSERT(!memcmp(other_hypercall_insn, hypercall_insn,
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HYPERCALL_INSN_SIZE));
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} else {
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GUEST_ASSERT(!ret);
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GUEST_ASSERT(!memcmp(native_hypercall_insn, hypercall_insn,
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HYPERCALL_INSN_SIZE));
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}
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GUEST_DONE();
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}
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static void enter_guest(struct kvm_vcpu *vcpu)
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{
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struct kvm_run *run = vcpu->run;
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struct ucall uc;
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vcpu_run(vcpu);
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switch (get_ucall(vcpu, &uc)) {
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case UCALL_SYNC:
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pr_info("%s: %016lx\n", (const char *)uc.args[2], uc.args[3]);
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break;
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case UCALL_DONE:
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return;
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case UCALL_ABORT:
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REPORT_GUEST_ASSERT(uc);
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default:
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TEST_FAIL("Unhandled ucall: %ld\nexit_reason: %u (%s)",
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uc.cmd, run->exit_reason, exit_reason_str(run->exit_reason));
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}
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}
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static void test_fix_hypercall(bool disable_quirk)
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{
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struct kvm_vcpu *vcpu;
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struct kvm_vm *vm;
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vm = vm_create_with_one_vcpu(&vcpu, guest_main);
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vm_init_descriptor_tables(vcpu->vm);
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vcpu_init_descriptor_tables(vcpu);
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vm_install_exception_handler(vcpu->vm, UD_VECTOR, guest_ud_handler);
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if (disable_quirk)
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vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2,
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KVM_X86_QUIRK_FIX_HYPERCALL_INSN);
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quirk_disabled = disable_quirk;
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sync_global_to_guest(vm, quirk_disabled);
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virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA);
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enter_guest(vcpu);
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}
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int main(void)
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{
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TEST_REQUIRE(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & KVM_X86_QUIRK_FIX_HYPERCALL_INSN);
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test_fix_hypercall(false);
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test_fix_hypercall(true);
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}
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