KVM: selftests: hyperv_svm_test: Introduce L2 TLB flush test

Enable Hyper-V L2 TLB flush and check that Hyper-V TLB flush hypercalls
from L2 don't exit to L1 unless 'TlbLockCount' is set in the Partition
assist page.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-48-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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

@@ -76,6 +76,10 @@ struct hv_vmcb_enlightenments {
  */
 #define HV_VMCB_NESTED_ENLIGHTENMENTS (1U << 31)
 
+/* Synthetic VM-Exit */
+#define HV_SVM_EXITCODE_ENL			0xf0000000
+#define HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH	(1)
+
 struct __attribute__ ((__packed__)) vmcb_control_area {
 	u32 intercept_cr;
 	u32 intercept_dr;

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

@@ -34,6 +34,8 @@ static inline void rdmsr_from_l2(uint32_t msr)
 
 void l2_guest_code(void)
 {
+	u64 unused;
+
 	GUEST_SYNC(3);
 	/* Exit to L1 */
 	vmmcall();
@@ -47,11 +49,28 @@ void l2_guest_code(void)
 
 	GUEST_SYNC(5);
 
+	/* L2 TLB flush tests */
+	hyperv_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE |
+			 HV_HYPERCALL_FAST_BIT, 0x0,
+			 HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES |
+			 HV_FLUSH_ALL_PROCESSORS);
+	rdmsr_from_l2(MSR_FS_BASE);
+	/*
+	 * Note: hypercall status (RAX) is not preserved correctly by L1 after
+	 * synthetic vmexit, use unchecked version.
+	 */
+	__hyperv_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE |
+			   HV_HYPERCALL_FAST_BIT, 0x0,
+			   HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES |
+			   HV_FLUSH_ALL_PROCESSORS, &unused);
+
 	/* Done, exit to L1 and never come back.  */
 	vmmcall();
 }
 
-static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
+static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm,
+						    struct hyperv_test_pages *hv_pages,
+						    vm_vaddr_t pgs_gpa)
 {
 	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 	struct vmcb *vmcb = svm->vmcb;
@@ -59,13 +78,23 @@ static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
 
 	GUEST_SYNC(1);
 
-	wrmsr(HV_X64_MSR_GUEST_OS_ID, (u64)0x8100 << 48);
+	wrmsr(HV_X64_MSR_GUEST_OS_ID, HYPERV_LINUX_OS_ID);
+	wrmsr(HV_X64_MSR_HYPERCALL, pgs_gpa);
+	enable_vp_assist(hv_pages->vp_assist_gpa, hv_pages->vp_assist);
 
 	GUEST_ASSERT(svm->vmcb_gpa);
 	/* Prepare for L2 execution. */
 	generic_svm_setup(svm, l2_guest_code,
 			  &l2_guest_stack[L2_GUEST_STACK_SIZE]);
 
+	/* L2 TLB flush setup */
+	hve->partition_assist_page = hv_pages->partition_assist_gpa;
+	hve->hv_enlightenments_control.nested_flush_hypercall = 1;
+	hve->hv_vm_id = 1;
+	hve->hv_vp_id = 1;
+	current_vp_assist->nested_control.features.directhypercall = 1;
+	*(u32 *)(hv_pages->partition_assist) = 0;
+
 	GUEST_SYNC(2);
 	run_guest(vmcb, svm->vmcb_gpa);
 	GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
@@ -100,6 +129,20 @@ static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
 	GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR);
 	vmcb->save.rip += 2; /* rdmsr */
 
+
+	/*
+	 * L2 TLB flush test. First VMCALL should be handled directly by L0,
+	 * no VMCALL exit expected.
+	 */
+	run_guest(vmcb, svm->vmcb_gpa);
+	GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR);
+	vmcb->save.rip += 2; /* rdmsr */
+	/* Enable synthetic vmexit */
+	*(u32 *)(hv_pages->partition_assist) = 1;
+	run_guest(vmcb, svm->vmcb_gpa);
+	GUEST_ASSERT(vmcb->control.exit_code == HV_SVM_EXITCODE_ENL);
+	GUEST_ASSERT(vmcb->control.exit_info_1 == HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH);
+
 	run_guest(vmcb, svm->vmcb_gpa);
 	GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
 	GUEST_SYNC(6);
@@ -109,8 +152,8 @@ static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
 
 int main(int argc, char *argv[])
 {
-	vm_vaddr_t nested_gva = 0;
-
+	vm_vaddr_t nested_gva = 0, hv_pages_gva = 0;
+	vm_vaddr_t hcall_page;
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 	struct kvm_run *run;
@@ -124,7 +167,13 @@ int main(int argc, char *argv[])
 	vcpu_set_hv_cpuid(vcpu);
 	run = vcpu->run;
 	vcpu_alloc_svm(vm, &nested_gva);
-	vcpu_args_set(vcpu, 1, nested_gva);
+	vcpu_alloc_hyperv_test_pages(vm, &hv_pages_gva);
+
+	hcall_page = vm_vaddr_alloc_pages(vm, 1);
+	memset(addr_gva2hva(vm, hcall_page), 0x0,  getpagesize());
+
+	vcpu_args_set(vcpu, 3, nested_gva, hv_pages_gva, addr_gva2gpa(vm, hcall_page));
+	vcpu_set_msr(vcpu, HV_X64_MSR_VP_INDEX, vcpu->id);
 
 	for (stage = 1;; stage++) {
 		vcpu_run(vcpu);