monitor_mwait_test.c

  1// SPDX-License-Identifier: GPL-2.0
  2#include <fcntl.h>
  3#include <stdio.h>
  4#include <stdlib.h>
  5#include <string.h>
  6#include <sys/ioctl.h>
  7
  8#include "kvm_util.h"
  9#include "processor.h"
 10#include "kselftest.h"
 11
 12#define CPUID_MWAIT (1u << 3)
 13
 14enum monitor_mwait_testcases {
 15	MWAIT_QUIRK_DISABLED = BIT(0),
 16	MISC_ENABLES_QUIRK_DISABLED = BIT(1),
 17	MWAIT_DISABLED = BIT(2),
 18	CPUID_DISABLED = BIT(3),
 19	TEST_MAX = CPUID_DISABLED * 2 - 1,
 20};
 21
 22/*
 23 * If both MWAIT and its quirk are disabled, MONITOR/MWAIT should #UD, in all
 24 * other scenarios KVM should emulate them as nops.
 25 */
 26#define GUEST_ASSERT_MONITOR_MWAIT(insn, testcase, vector)		\
 27do {									\
 28	bool fault_wanted = ((testcase) & MWAIT_QUIRK_DISABLED) &&	\
 29			    ((testcase) & MWAIT_DISABLED);		\
 30									\
 31	if (fault_wanted)						\
 32		__GUEST_ASSERT((vector) == UD_VECTOR,			\
 33			       "Expected #UD on " insn " for testcase '0x%x', got %s", \
 34			       testcase, ex_str(vector));		\
 35	else								\
 36		__GUEST_ASSERT(!(vector),				\
 37			       "Expected success on " insn " for testcase '0x%x', got %s", \
 38			       testcase, ex_str(vector));		\
 39} while (0)
 40
 41static void guest_monitor_wait(void *arg)
 42{
 43	int testcase = (int) (long) arg;
 44	u8 vector;
 45
 46	u64 val = rdmsr(MSR_IA32_MISC_ENABLE) & ~MSR_IA32_MISC_ENABLE_MWAIT;
 47	if (!(testcase & MWAIT_DISABLED))
 48		val |= MSR_IA32_MISC_ENABLE_MWAIT;
 49	wrmsr(MSR_IA32_MISC_ENABLE, val);
 50
 51	__GUEST_ASSERT(this_cpu_has(X86_FEATURE_MWAIT) == !(testcase & MWAIT_DISABLED),
 52		       "Expected CPUID.MWAIT %s\n",
 53		       (testcase & MWAIT_DISABLED) ? "cleared" : "set");
 54
 55	/*
 56	 * Arbitrarily MONITOR this function, SVM performs fault checks before
 57	 * intercept checks, so the inputs for MONITOR and MWAIT must be valid.
 58	 */
 59	vector = kvm_asm_safe("monitor", "a"(guest_monitor_wait), "c"(0), "d"(0));
 60	GUEST_ASSERT_MONITOR_MWAIT("MONITOR", testcase, vector);
 61
 62	vector = kvm_asm_safe("mwait", "a"(guest_monitor_wait), "c"(0), "d"(0));
 63	GUEST_ASSERT_MONITOR_MWAIT("MWAIT", testcase, vector);
 64
 65	GUEST_DONE();
 66}
 67
 68int main(int argc, char *argv[])
 69{
 70	uint64_t disabled_quirks;
 71	struct kvm_vcpu *vcpu;
 72	struct kvm_vm *vm;
 73	struct ucall uc;
 74	int testcase;
 75	char test[80];
 76
 77	TEST_REQUIRE(this_cpu_has(X86_FEATURE_MWAIT));
 78	TEST_REQUIRE(kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2));
 79
 80	ksft_print_header();
 81	ksft_set_plan(12);
 82	for (testcase = 0; testcase <= TEST_MAX; testcase++) {
 83		vm = vm_create_with_one_vcpu(&vcpu, guest_monitor_wait);
 84		vcpu_args_set(vcpu, 1, (void *)(long)testcase);
 85
 86		disabled_quirks = 0;
 87		if (testcase & MWAIT_QUIRK_DISABLED) {
 88			disabled_quirks |= KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS;
 89			strcpy(test, "MWAIT can fault");
 90		} else {
 91			strcpy(test, "MWAIT never faults");
 92		}
 93		if (testcase & MISC_ENABLES_QUIRK_DISABLED) {
 94			disabled_quirks |= KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT;
 95			strcat(test, ", MISC_ENABLE updates CPUID");
 96		} else {
 97			strcat(test, ", no CPUID updates");
 98		}
 99
100		vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, disabled_quirks);
101
102		if (!(testcase & MISC_ENABLES_QUIRK_DISABLED) &&
103		    (!!(testcase & CPUID_DISABLED) ^ !!(testcase & MWAIT_DISABLED)))
104			continue;
105
106		if (testcase & CPUID_DISABLED) {
107			strcat(test, ", CPUID clear");
108			vcpu_clear_cpuid_feature(vcpu, X86_FEATURE_MWAIT);
109		} else {
110			strcat(test, ", CPUID set");
111			vcpu_set_cpuid_feature(vcpu, X86_FEATURE_MWAIT);
112		}
113
114		if (testcase & MWAIT_DISABLED)
115			strcat(test, ", MWAIT disabled");
116
117		vcpu_run(vcpu);
118		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
119
120		switch (get_ucall(vcpu, &uc)) {
121		case UCALL_ABORT:
122			/* Detected in vcpu_run */
123			break;
124		case UCALL_DONE:
125			ksft_test_result_pass("%s\n", test);
126			break;
127		default:
128			TEST_FAIL("Unknown ucall %lu", uc.cmd);
129			break;
130		}
131		kvm_vm_free(vm);
132	}
133	ksft_finished();
134
135	return 0;
136}