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// 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);
}
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