KVM: selftests: evmcs_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: <20221101145426.251680-47-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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

@@ -237,6 +237,8 @@ struct hv_enlightened_vmcs {
 #define HV_VMX_ENLIGHTENED_CLEAN_FIELD_ENLIGHTENMENTSCONTROL    BIT(15)
 #define HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL                      0xFFFF
 
+#define HV_VMX_SYNTHETIC_EXIT_REASON_TRAP_AFTER_FLUSH 0x10000031
+
 extern struct hv_enlightened_vmcs *current_evmcs;
 
 int vcpu_enable_evmcs(struct kvm_vcpu *vcpu);

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

@@ -16,6 +16,7 @@
 
 #include "kvm_util.h"
 
+#include "hyperv.h"
 #include "vmx.h"
 
 static int ud_count;
@@ -41,6 +42,8 @@ static inline void rdmsr_from_l2(uint32_t msr)
 /* Exit to L1 from L2 with RDMSR instruction */
 void l2_guest_code(void)
 {
+	u64 unused;
+
 	GUEST_SYNC(7);
 
 	GUEST_SYNC(8);
@@ -57,15 +60,31 @@ void l2_guest_code(void)
 	vmcall();
 	rdmsr_from_l2(MSR_GS_BASE); /* intercepted */
 
+	/* 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.  */
 	vmcall();
 }
 
-void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages)
+void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages,
+		vm_vaddr_t hv_hcall_page_gpa)
 {
 #define L2_GUEST_STACK_SIZE 64
 	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 
+	wrmsr(HV_X64_MSR_GUEST_OS_ID, HYPERV_LINUX_OS_ID);
+	wrmsr(HV_X64_MSR_HYPERCALL, hv_hcall_page_gpa);
+
 	x2apic_enable();
 
 	GUEST_SYNC(1);
@@ -95,7 +114,17 @@ void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages)
 	vmwrite(PIN_BASED_VM_EXEC_CONTROL, vmreadz(PIN_BASED_VM_EXEC_CONTROL) |
 		PIN_BASED_NMI_EXITING);
 
+	/* L2 TLB flush setup */
+	current_evmcs->partition_assist_page = hv_pages->partition_assist_gpa;
+	current_evmcs->hv_enlightenments_control.nested_flush_hypercall = 1;
+	current_evmcs->hv_vm_id = 1;
+	current_evmcs->hv_vp_id = 1;
+	current_vp_assist->nested_control.features.directhypercall = 1;
+	*(u32 *)(hv_pages->partition_assist) = 0;
+
 	GUEST_ASSERT(!vmlaunch());
+	GUEST_ASSERT_EQ(vmreadz(VM_EXIT_REASON), EXIT_REASON_EXCEPTION_NMI);
+	GUEST_ASSERT_EQ((vmreadz(VM_EXIT_INTR_INFO) & 0xff), NMI_VECTOR);
 	GUEST_ASSERT(vmptrstz() == hv_pages->enlightened_vmcs_gpa);
 
 	/*
@@ -139,6 +168,18 @@ void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages)
 	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_MSR_READ);
 	current_evmcs->guest_rip += 2; /* rdmsr */
 
+	/*
+	 * L2 TLB flush test. First VMCALL should be handled directly by L0,
+	 * no VMCALL exit expected.
+	 */
+	GUEST_ASSERT(!vmresume());
+	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_MSR_READ);
+	current_evmcs->guest_rip += 2; /* rdmsr */
+	/* Enable synthetic vmexit */
+	*(u32 *)(hv_pages->partition_assist) = 1;
+	GUEST_ASSERT(!vmresume());
+	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == HV_VMX_SYNTHETIC_EXIT_REASON_TRAP_AFTER_FLUSH);
+
 	GUEST_ASSERT(!vmresume());
 	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
 	GUEST_SYNC(11);
@@ -192,6 +233,7 @@ static struct kvm_vcpu *save_restore_vm(struct kvm_vm *vm,
 int main(int argc, char *argv[])
 {
 	vm_vaddr_t vmx_pages_gva = 0, hv_pages_gva = 0;
+	vm_vaddr_t hcall_page;
 
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
@@ -205,12 +247,16 @@ int main(int argc, char *argv[])
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_NESTED_STATE));
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_HYPERV_ENLIGHTENED_VMCS));
 
+	hcall_page = vm_vaddr_alloc_pages(vm, 1);
+	memset(addr_gva2hva(vm, hcall_page), 0x0,  getpagesize());
+
 	vcpu_set_hv_cpuid(vcpu);
 	vcpu_enable_evmcs(vcpu);
 
 	vcpu_alloc_vmx(vm, &vmx_pages_gva);
 	vcpu_alloc_hyperv_test_pages(vm, &hv_pages_gva);
-	vcpu_args_set(vcpu, 2, vmx_pages_gva, hv_pages_gva);
+	vcpu_args_set(vcpu, 3, vmx_pages_gva, hv_pages_gva, addr_gva2gpa(vm, hcall_page));
+	vcpu_set_msr(vcpu, HV_X64_MSR_VP_INDEX, vcpu->id);
 
 	vm_init_descriptor_tables(vm);
 	vcpu_init_descriptor_tables(vcpu);