KVM: selftests: Test access to XMM fast hypercalls

Check that #UD is raised if bit 16 is clear in
HYPERV_CPUID_FEATURES.EDX and an 'XMM fast' hypercall is issued.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Siddharth Chandrasekaran <sidcha@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210730122625.112848-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/include/x86_64/hyperv.h

@@ -117,7 +117,7 @@
 #define HV_X64_GUEST_DEBUGGING_AVAILABLE		BIT(1)
 #define HV_X64_PERF_MONITOR_AVAILABLE			BIT(2)
 #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE	BIT(3)
-#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE		BIT(4)
+#define HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE		BIT(4)
 #define HV_X64_GUEST_IDLE_STATE_AVAILABLE		BIT(5)
 #define HV_FEATURE_FREQUENCY_MSRS_AVAILABLE		BIT(8)
 #define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE		BIT(10)
@@ -182,4 +182,7 @@
 #define HV_STATUS_INVALID_CONNECTION_ID		18
 #define HV_STATUS_INSUFFICIENT_BUFFERS		19
 
+/* hypercall options */
+#define HV_HYPERCALL_FAST_BIT		BIT(16)
+
 #endif /* !SELFTEST_KVM_HYPERV_H */

tools/testing/selftests/kvm/x86_64/hyperv_features.c

@@ -47,6 +47,7 @@ static void do_wrmsr(u32 idx, u64 val)
 }
 
 static int nr_gp;
+static int nr_ud;
 
 static inline u64 hypercall(u64 control, vm_vaddr_t input_address,
 			    vm_vaddr_t output_address)
@@ -80,6 +81,12 @@ static void guest_gp_handler(struct ex_regs *regs)
 		regs->rip = (uint64_t)&wrmsr_end;
 }
 
+static void guest_ud_handler(struct ex_regs *regs)
+{
+	nr_ud++;
+	regs->rip += 3;
+}
+
 struct msr_data {
 	uint32_t idx;
 	bool available;
@@ -90,6 +97,7 @@ struct msr_data {
 struct hcall_data {
 	uint64_t control;
 	uint64_t expect;
+	bool ud_expected;
 };
 
 static void guest_msr(struct msr_data *msr)
@@ -117,13 +125,26 @@ static void guest_msr(struct msr_data *msr)
 static void guest_hcall(vm_vaddr_t pgs_gpa, struct hcall_data *hcall)
 {
 	int i = 0;
+	u64 res, input, output;
 
 	wrmsr(HV_X64_MSR_GUEST_OS_ID, LINUX_OS_ID);
 	wrmsr(HV_X64_MSR_HYPERCALL, pgs_gpa);
 
 	while (hcall->control) {
-		GUEST_ASSERT(hypercall(hcall->control, pgs_gpa,
-				       pgs_gpa + 4096) == hcall->expect);
+		nr_ud = 0;
+		if (!(hcall->control & HV_HYPERCALL_FAST_BIT)) {
+			input = pgs_gpa;
+			output = pgs_gpa + 4096;
+		} else {
+			input = output = 0;
+		}
+
+		res = hypercall(hcall->control, input, output);
+		if (hcall->ud_expected)
+			GUEST_ASSERT(nr_ud == 1);
+		else
+			GUEST_ASSERT(res == hcall->expect);
+
 		GUEST_SYNC(i++);
 	}
 
@@ -552,8 +573,18 @@ static void guest_test_hcalls_access(struct kvm_vm *vm, struct hcall_data *hcall
 			recomm.ebx = 0xfff;
 			hcall->expect = HV_STATUS_SUCCESS;
 			break;
-
 		case 17:
+			/* XMM fast hypercall */
+			hcall->control = HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE | HV_HYPERCALL_FAST_BIT;
+			hcall->ud_expected = true;
+			break;
+		case 18:
+			feat.edx |= HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE;
+			hcall->ud_expected = false;
+			hcall->expect = HV_STATUS_SUCCESS;
+			break;
+
+		case 19:
 			/* END */
 			hcall->control = 0;
 			break;
@@ -625,6 +656,10 @@ int main(void)
 	/* Test hypercalls */
 	vm = vm_create_default(VCPU_ID, 0, guest_hcall);
 
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vm, VCPU_ID);
+	vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler);
+
 	/* Hypercall input/output */
 	hcall_page = vm_vaddr_alloc_pages(vm, 2);
 	memset(addr_gva2hva(vm, hcall_page), 0x0, 2 * getpagesize());