[PATCH v7 29/30] KVM: selftests: TDX: Add TDX UPM selftests for implicit conversion

[Sagi Shahar <sagis@google.com>]

From: Ackerley Tng <ackerleytng@google.com>

This tests the use of guest memory without explicit TDG.VP.VMCALL<MapGPA>
calls.

Provide a 2MB memory region to the TDX guest with a 40KB focus area at
offset 1MB intended to be shared between host and guest. The guest does
not request memory to be shared or private using TDG.VP.VMCALL<MapGPA> but
instead relies on memory to be converted automatically based on its
access via shared or private mapping. The host automatically
converts the memory when guest exits with KVM_EXIT_MEMORY_FAULT.

The 2MB region starts out as private with the guest filling it with a
pattern, followed by a check from the host to ensure the host is not able
to see the pattern. The guest then accesses the 40KB focus area via
its shared mapping to trigger implicit conversion followed by checks that
the host and guest has the same view of the memory. Finally the guest
accesses the 40KB memory via its private mapping to trigger the implicit
conversion to private followed by checks to confirm this is the case.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Signed-off-by: Sagi Shahar <sagis@google.com>
---
 .../testing/selftests/kvm/x86/tdx_upm_test.c  | 88 ++++++++++++++++---
 1 file changed, 76 insertions(+), 12 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86/tdx_upm_test.c b/tools/testing/selftests/kvm/x86/tdx_upm_test.c
index 387258ab1a62..2ea5bf6d24b7 100644
--- a/tools/testing/selftests/kvm/x86/tdx_upm_test.c
+++ b/tools/testing/selftests/kvm/x86/tdx_upm_test.c
@@ -150,10 +150,10 @@ enum {
  * Does vcpu_run, and also manages memory conversions if requested by the TD.
  */
 void vcpu_run_and_manage_memory_conversions(struct kvm_vm *vm,
-					    struct kvm_vcpu *vcpu)
+					    struct kvm_vcpu *vcpu, bool handle_conversions)
 {
 	for (;;) {
-		vcpu_run(vcpu);
+		_vcpu_run(vcpu);
 		if (vcpu->run->exit_reason == KVM_EXIT_HYPERCALL &&
 		    vcpu->run->hypercall.nr == KVM_HC_MAP_GPA_RANGE) {
 			uint64_t gpa = vcpu->run->hypercall.args[0];
@@ -164,6 +164,13 @@ void vcpu_run_and_manage_memory_conversions(struct kvm_vm *vm,
 						  KVM_MAP_GPA_RANGE_ENCRYPTED);
 			vcpu->run->hypercall.ret = 0;
 			continue;
+		} else if (handle_conversions &&
+			vcpu->run->exit_reason == KVM_EXIT_MEMORY_FAULT) {
+			handle_memory_conversion(vm, vcpu->id, vcpu->run->memory_fault.gpa,
+						 vcpu->run->memory_fault.size,
+						 vcpu->run->memory_fault.flags ==
+						  KVM_MEMORY_EXIT_FLAG_PRIVATE);
+			continue;
 		} else if (vcpu->run->exit_reason == KVM_EXIT_IO &&
 			   vcpu->run->io.port == TDX_UPM_TEST_ACCEPT_PRINT_PORT) {
 			uint64_t gpa = tdx_test_read_64bit(vcpu,
@@ -241,8 +248,48 @@ static void guest_upm_explicit(void)
 	tdx_test_success();
 }
 
+static void guest_upm_implicit(void)
+{
+	struct tdx_upm_test_area *test_area_gva_private =
+		(struct tdx_upm_test_area *)TDX_UPM_TEST_AREA_GVA_PRIVATE;
+	struct tdx_upm_test_area *test_area_gva_shared =
+		(struct tdx_upm_test_area *)TDX_UPM_TEST_AREA_GVA_SHARED;
+
+	/* Check: host reading private memory does not modify guest's view */
+	fill_test_area(test_area_gva_private, PATTERN_GUEST_GENERAL);
+
+	tdx_test_report_to_user_space(SYNC_CHECK_READ_PRIVATE_MEMORY_FROM_HOST);
+
+	TDX_UPM_TEST_ASSERT(check_test_area(test_area_gva_private, PATTERN_GUEST_GENERAL));
+
+	/* Use focus area as shared */
+	fill_focus_area(test_area_gva_shared, PATTERN_GUEST_FOCUS);
+
+	/* General areas should not be affected */
+	TDX_UPM_TEST_ASSERT(check_general_areas(test_area_gva_private, PATTERN_GUEST_GENERAL));
+
+	tdx_test_report_to_user_space(SYNC_CHECK_READ_SHARED_MEMORY_FROM_HOST);
+
+	/* Check that guest has the same view of shared memory */
+	TDX_UPM_TEST_ASSERT(check_focus_area(test_area_gva_shared, PATTERN_HOST_FOCUS));
+
+	/* Use focus area as private */
+	fill_focus_area(test_area_gva_private, PATTERN_GUEST_FOCUS);
+
+	/* General areas should be unaffected by remapping */
+	TDX_UPM_TEST_ASSERT(check_general_areas(test_area_gva_private, PATTERN_GUEST_GENERAL));
+
+	tdx_test_report_to_user_space(SYNC_CHECK_READ_PRIVATE_MEMORY_FROM_HOST_AGAIN);
+
+	/* Check that guest can use private memory after focus area is remapped as private */
+	TDX_UPM_TEST_ASSERT(fill_and_check(test_area_gva_private, PATTERN_GUEST_GENERAL));
+
+	tdx_test_success();
+}
+
 static void run_selftest(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
-			 struct tdx_upm_test_area *test_area_base_hva)
+			 struct tdx_upm_test_area *test_area_base_hva,
+			 bool implicit)
 {
 	tdx_run(vcpu);
 	tdx_test_assert_io(vcpu, TDX_TEST_REPORT_PORT, TDX_TEST_REPORT_SIZE,
@@ -260,7 +307,7 @@ static void run_selftest(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
 	TEST_ASSERT(check_test_area(test_area_base_hva, PATTERN_CONFIDENCE_CHECK),
 		    "Host should read PATTERN_CONFIDENCE_CHECK from guest's private memory.");
 
-	vcpu_run_and_manage_memory_conversions(vm, vcpu);
+	vcpu_run_and_manage_memory_conversions(vm, vcpu, implicit);
 	tdx_test_assert_io(vcpu, TDX_TEST_REPORT_PORT, TDX_TEST_REPORT_SIZE,
 			   PORT_WRITE);
 	TEST_ASSERT_EQ(*(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset),
@@ -276,7 +323,7 @@ static void run_selftest(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
 	TEST_ASSERT(check_focus_area(test_area_base_hva, PATTERN_HOST_FOCUS),
 		    "Host should be able to use shared memory.");
 
-	vcpu_run_and_manage_memory_conversions(vm, vcpu);
+	vcpu_run_and_manage_memory_conversions(vm, vcpu, implicit);
 	tdx_test_assert_io(vcpu, TDX_TEST_REPORT_PORT, TDX_TEST_REPORT_SIZE,
 			   PORT_WRITE);
 	TEST_ASSERT_EQ(*(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset),
@@ -322,17 +369,19 @@ static void guest_ve_handler(struct ex_regs *regs)
 	TDX_UPM_TEST_ASSERT(!ret);
 }
 
-static void verify_upm_test(void)
+static void verify_upm_test(bool implicit)
 {
 	struct tdx_upm_test_area *test_area_base_hva;
 	vm_vaddr_t test_area_gva_private;
 	uint64_t test_area_npages;
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
+	void *guest_code;
 
 	vm = td_create();
 	td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
-	vcpu = td_vcpu_add(vm, 0, guest_upm_explicit);
+	guest_code = implicit ? guest_upm_implicit : guest_upm_explicit;
+	vcpu = td_vcpu_add(vm, 0, guest_code);
 
 	vm_install_exception_handler(vm, VE_VECTOR, guest_ve_handler);
 
@@ -373,15 +422,28 @@ static void verify_upm_test(void)
 
 	td_finalize(vm);
 
-	printf("Verifying UPM functionality: explicit MapGPA\n");
+	if (implicit)
+		printf("Verifying UPM functionality: implicit conversion\n");
+	else
+		printf("Verifying UPM functionality: explicit MapGPA\n");
 
 	vm_enable_cap(vm, KVM_CAP_EXIT_HYPERCALL, BIT_ULL(KVM_HC_MAP_GPA_RANGE));
 
-	run_selftest(vm, vcpu, test_area_base_hva);
+	run_selftest(vm, vcpu, test_area_base_hva, implicit);
 
 	kvm_vm_free(vm);
 }
 
+void verify_upm_test_explicit(void)
+{
+	verify_upm_test(false);
+}
+
+void verify_upm_test_implicit(void)
+{
+	verify_upm_test(true);
+}
+
 int main(int argc, char **argv)
 {
 	ksft_print_header();
@@ -389,9 +451,11 @@ int main(int argc, char **argv)
 	if (!is_tdx_enabled())
 		ksft_exit_skip("TDX is not supported by the KVM. Exiting.\n");
 
-	ksft_set_plan(1);
-	ksft_test_result(!run_in_new_process(&verify_upm_test),
-			 "verify_upm_test\n");
+	ksft_set_plan(2);
+	ksft_test_result(!run_in_new_process(&verify_upm_test_explicit),
+			 "verify_upm_test_explicit\n");
+	ksft_test_result(!run_in_new_process(&verify_upm_test_implicit),
+			 "verify_upm_test_implicit\n");
 
 	ksft_finished();
 }
-- 
2.50.0.rc2.692.g299adb8693-goog