1 files changed, 135 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86/monitor_mwait_test.c b/tools/testing/selftests/kvm/x86/monitor_mwait_test.c
new file mode 100644
index 000000000000..390ae2d87493
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86/monitor_mwait_test.c
@@ -0,0 +1,135 @@
+// 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"
+#include "kselftest.h"
+
+#define CPUID_MWAIT (1u << 3)
+
+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,
+};
+
+/*
+ * If both MWAIT and its quirk are disabled, MONITOR/MWAIT should #UD, in all
+ * other scenarios KVM should emulate them as nops.
+ */
+#define GUEST_ASSERT_MONITOR_MWAIT(insn, testcase, vector)		\
+do {									\
+	bool fault_wanted = ((testcase) & MWAIT_QUIRK_DISABLED) &&	\
+			    ((testcase) & MWAIT_DISABLED);		\
+									\
+	if (fault_wanted)						\
+		__GUEST_ASSERT((vector) == UD_VECTOR,			\
+			       "Expected #UD on " insn " for testcase '0x%x', got '0x%x'", \
+			       testcase, vector);			\
+	else								\
+		__GUEST_ASSERT(!(vector),				\
+			       "Expected success on " insn " for testcase '0x%x', got '0x%x'", \
+			       testcase, vector);			\
+} while (0)
+
+static void guest_monitor_wait(void *arg)
+{
+	int testcase = (int) (long) arg;
+	u8 vector;
+
+	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
+	 * intercept checks, so the inputs for MONITOR and MWAIT must be valid.
+	 */
+	vector = kvm_asm_safe("monitor", "a"(guest_monitor_wait), "c"(0), "d"(0));
+	GUEST_ASSERT_MONITOR_MWAIT("MONITOR", testcase, vector);
+
+	vector = kvm_asm_safe("mwait", "a"(guest_monitor_wait), "c"(0), "d"(0));
+	GUEST_ASSERT_MONITOR_MWAIT("MWAIT", testcase, vector);
+
+	GUEST_DONE();
+}
+
+int main(int argc, char *argv[])
+{
+	uint64_t disabled_quirks;
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	struct ucall uc;
+	int testcase;
+	char test[80];
+
+	TEST_REQUIRE(kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2));
+
+	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");
+
+		vcpu_run(vcpu);
+		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
+
+		switch (get_ucall(vcpu, &uc)) {
+		case UCALL_ABORT:
+			/* Detected in vcpu_run */
+			break;
+		case UCALL_DONE:
+			ksft_test_result_pass("%s\n", test);
+			break;
+		default:
+			TEST_FAIL("Unknown ucall %lu", uc.cmd);
+			break;
+		}
+		kvm_vm_free(vm);
+	}
+	ksft_finished();
+
+	return 0;
+}