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KVM: selftests: Add MONITOR/MWAIT quirk test

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Add a test to verify the "MONITOR/MWAIT never fault" quirk, and as a
bonus, also verify the related "MISC_ENABLES ignores ENABLE_MWAIT" quirk.

If the "never fault" quirk is enabled, MONITOR/MWAIT should always be
emulated as NOPs, even if they're reported as disabled in guest CPUID.
Use the MISC_ENABLES quirk to coerce KVM into toggling the MWAIT CPUID
enable, as KVM now disallows manually toggling CPUID bits after running
the vCPU.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220608224516.3788274-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-06-08 22:45:16 +00:00 committed by Paolo Bonzini
parent cc5851c6be
commit 2325d4dd73
4 changed files with 139 additions and 0 deletions
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1
tools/testing/selftests/kvm/.gitignore vendored
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@ -28,6 +28,7 @@
/x86_64/max_vcpuid_cap_test
/x86_64/mmio_warning_test
/x86_64/mmu_role_test
/x86_64/monitor_mwait_test
/x86_64/platform_info_test
/x86_64/pmu_event_filter_test
/x86_64/set_boot_cpu_id

1
tools/testing/selftests/kvm/Makefile
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@ -84,6 +84,7 @@ 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
TEST_GEN_PROGS_x86_64 += x86_64/mmu_role_test
TEST_GEN_PROGS_x86_64 += x86_64/monitor_mwait_test
TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test
TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id

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tools/testing/selftests/kvm/x86_64/monitor_mwait_test
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137
tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c Normal file
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@ -0,0 +1,137 @@
// SPDX-License-Identifier: GPL-2.0
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include "kvm_util.h"
#include "processor.h"
#define X86_FEATURE_MWAIT (1u << 3)
enum monitor_mwait_testcases {
MWAIT_QUIRK_DISABLED = BIT(0),
MISC_ENABLES_QUIRK_DISABLED = BIT(1),
MWAIT_DISABLED = BIT(2),
};
static void guest_monitor_wait(int testcase)
{
/*
* If both MWAIT and its quirk are disabled, MONITOR/MWAIT should #UD,
* in all other scenarios KVM should emulate them as nops.
*/
bool fault_wanted = (testcase & MWAIT_QUIRK_DISABLED) &&
(testcase & MWAIT_DISABLED);
u8 vector;
GUEST_SYNC(testcase);
vector = kvm_asm_safe("monitor");
if (fault_wanted)
GUEST_ASSERT_2(vector == UD_VECTOR, testcase, vector);
else
GUEST_ASSERT_2(!vector, testcase, vector);
vector = kvm_asm_safe("monitor");
if (fault_wanted)
GUEST_ASSERT_2(vector == UD_VECTOR, testcase, vector);
else
GUEST_ASSERT_2(!vector, testcase, vector);
}
static void guest_code(void)
{
guest_monitor_wait(MWAIT_DISABLED);
guest_monitor_wait(MWAIT_QUIRK_DISABLED | MWAIT_DISABLED);
guest_monitor_wait(MISC_ENABLES_QUIRK_DISABLED | MWAIT_DISABLED);
guest_monitor_wait(MISC_ENABLES_QUIRK_DISABLED);
guest_monitor_wait(MISC_ENABLES_QUIRK_DISABLED | MWAIT_QUIRK_DISABLED | MWAIT_DISABLED);
guest_monitor_wait(MISC_ENABLES_QUIRK_DISABLED | MWAIT_QUIRK_DISABLED);
GUEST_DONE();
}
int main(int argc, char *argv[])
{
uint64_t disabled_quirks;
struct kvm_cpuid2 *cpuid;
struct kvm_cpuid_entry2 *entry;
struct kvm_vcpu *vcpu;
struct kvm_run *run;
struct kvm_vm *vm;
struct ucall uc;
int testcase;
TEST_REQUIRE(kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2));
cpuid = kvm_get_supported_cpuid();
entry = kvm_get_supported_cpuid_index(1, 0);
entry->ecx &= ~X86_FEATURE_MWAIT;
set_cpuid(cpuid, entry);
vm = vm_create_with_one_vcpu(&vcpu, guest_code);
vcpu_set_cpuid(vcpu, cpuid);
run = vcpu->run;
vm_init_descriptor_tables(vm);
vcpu_init_descriptor_tables(vcpu);
while (1) {
vcpu_run(vcpu);
TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
"Unexpected exit reason: %u (%s),\n",
run->exit_reason,
exit_reason_str(run->exit_reason));
switch (get_ucall(vcpu, &uc)) {
case UCALL_SYNC:
testcase = uc.args[1];
break;
case UCALL_ABORT:
TEST_FAIL("%s at %s:%ld, testcase = %lx, vector = %ld",
(const char *)uc.args[0], __FILE__,
uc.args[1], uc.args[2], uc.args[3]);
goto done;
case UCALL_DONE:
goto done;
default:
TEST_FAIL("Unknown ucall %lu", uc.cmd);
goto done;
}
disabled_quirks = 0;
if (testcase & MWAIT_QUIRK_DISABLED)
disabled_quirks |= KVM_X86_QUIRK_MWAIT_NEVER_FAULTS;
if (testcase & MISC_ENABLES_QUIRK_DISABLED)
disabled_quirks |= KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT;
vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, disabled_quirks);
/*
* If the MISC_ENABLES quirk (KVM neglects to update CPUID to
* enable/disable MWAIT) is disabled, toggle the ENABLE_MWAIT
* bit in MISC_ENABLES accordingly. If the quirk is enabled,
* the only valid configuration is MWAIT disabled, as CPUID
* can't be manually changed after running the vCPU.
*/
if (!(testcase & MISC_ENABLES_QUIRK_DISABLED)) {
TEST_ASSERT(testcase & MWAIT_DISABLED,
"Can't toggle CPUID features after running vCPU");
continue;
}
vcpu_set_msr(vcpu, MSR_IA32_MISC_ENABLE,
(testcase & MWAIT_DISABLED) ? 0 : MSR_IA32_MISC_ENABLE_MWAIT);
}
done:
kvm_vm_free(vm);
return 0;
}