1 files changed, 129 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..2b550eff35f1
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86/monitor_mwait_test.c
@@ -0,0 +1,129 @@
+// 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 CPUID_MWAIT (1u << 3)
+
+enum monitor_mwait_testcases {
+	MWAIT_QUIRK_DISABLED = BIT(0),
+	MISC_ENABLES_QUIRK_DISABLED = BIT(1),
+	MWAIT_DISABLED = BIT(2),
+};
+
+/*
+ * 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(int testcase)
+{
+	u8 vector;
+
+	GUEST_SYNC(testcase);
+
+	/*
+	 * 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);
+}
+
+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_vcpu *vcpu;
+	struct kvm_vm *vm;
+	struct ucall uc;
+	int testcase;
+
+	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);
+
+	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;
+		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_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);
+	}
+
+done:
+	kvm_vm_free(vm);
+	return 0;
+}