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selftests: kvm: revamp MONITOR/MWAIT tests

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Run each testcase in a separate VMs to cover more possibilities;
move WRMSR close to MONITOR/MWAIT to test updating CPUID bits
while in the VM.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2025-03-20 11:42:55 -04:00
parent 782f9feaa9
commit 80fd663590
1 changed files with 57 additions and 51 deletions
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108
tools/testing/selftests/kvm/x86/monitor_mwait_test.c
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@ -7,6 +7,7 @@
#include "kvm_util.h"
#include "processor.h"
#include "kselftest.h"
#define CPUID_MWAIT (1u << 3)
@ -14,6 +15,8 @@ enum monitor_mwait_testcases {
MWAIT_QUIRK_DISABLED = BIT(0),
MISC_ENABLES_QUIRK_DISABLED = BIT(1),
MWAIT_DISABLED = BIT(2),
CPUID_DISABLED = BIT(3),
TEST_MAX = CPUID_DISABLED * 2 - 1,
};
/*
@ -35,11 +38,19 @@ do { \
testcase, vector); \
} while (0)
static void guest_monitor_wait(int testcase)
static void guest_monitor_wait(void *arg)
{
int testcase = (int) (long) arg;
u8 vector;
GUEST_SYNC(testcase);
u64 val = rdmsr(MSR_IA32_MISC_ENABLE) & ~MSR_IA32_MISC_ENABLE_MWAIT;
if (!(testcase & MWAIT_DISABLED))
val |= MSR_IA32_MISC_ENABLE_MWAIT;
wrmsr(MSR_IA32_MISC_ENABLE, val);
__GUEST_ASSERT(this_cpu_has(X86_FEATURE_MWAIT) == !(testcase & MWAIT_DISABLED),
"Expected CPUID.MWAIT %s\n",
(testcase & MWAIT_DISABLED) ? "cleared" : "set");
/*
* Arbitrarily MONITOR this function, SVM performs fault checks before
@ -50,19 +61,6 @@ static void guest_monitor_wait(int testcase)
vector = kvm_asm_safe("mwait", "a"(guest_monitor_wait), "c"(0), "d"(0));
GUEST_ASSERT_MONITOR_MWAIT("MWAIT", 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();
}
@ -74,56 +72,64 @@ int main(int argc, char *argv[])
struct kvm_vm *vm;
struct ucall uc;
int testcase;
char test[80];
TEST_REQUIRE(this_cpu_has(X86_FEATURE_MWAIT));
TEST_REQUIRE(kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2));
vm = vm_create_with_one_vcpu(&vcpu, guest_code);
vcpu_clear_cpuid_feature(vcpu, X86_FEATURE_MWAIT);
ksft_print_header();
ksft_set_plan(12);
for (testcase = 0; testcase <= TEST_MAX; testcase++) {
vm = vm_create_with_one_vcpu(&vcpu, guest_monitor_wait);
vcpu_args_set(vcpu, 1, (void *)(long)testcase);
disabled_quirks = 0;
if (testcase & MWAIT_QUIRK_DISABLED) {
disabled_quirks |= KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS;
strcpy(test, "MWAIT can fault");
} else {
strcpy(test, "MWAIT never faults");
}
if (testcase & MISC_ENABLES_QUIRK_DISABLED) {
disabled_quirks |= KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT;
strcat(test, ", MISC_ENABLE updates CPUID");
} else {
strcat(test, ", no CPUID updates");
}
vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, disabled_quirks);
if (!(testcase & MISC_ENABLES_QUIRK_DISABLED) &&
(!!(testcase & CPUID_DISABLED) ^ !!(testcase & MWAIT_DISABLED)))
continue;
if (testcase & CPUID_DISABLED) {
strcat(test, ", CPUID clear");
vcpu_clear_cpuid_feature(vcpu, X86_FEATURE_MWAIT);
} else {
strcat(test, ", CPUID set");
vcpu_set_cpuid_feature(vcpu, X86_FEATURE_MWAIT);
}
if (testcase & MWAIT_DISABLED)
strcat(test, ", MWAIT disabled");
while (1) {
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
switch (get_ucall(vcpu, &uc)) {
case UCALL_SYNC:
testcase = uc.args[1];
break;
case UCALL_ABORT:
REPORT_GUEST_ASSERT(uc);
goto done;
/* Detected in vcpu_run */
break;
case UCALL_DONE:
goto done;
ksft_test_result_pass("%s\n", test);
break;
default:
TEST_FAIL("Unknown ucall %lu", uc.cmd);
goto done;
break;
}
disabled_quirks = 0;
if (testcase & MWAIT_QUIRK_DISABLED)
disabled_quirks |= KVM_X86_QUIRK_MWAIT_NEVER_UD_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);
kvm_vm_free(vm);
}
ksft_finished();
done:
kvm_vm_free(vm);
return 0;
}