[RFC PATCH v2 13/17] KVM: selftest: TDX: Add TDX MMIO writes test

[Sagi Shahar <sagis@xxxxxxxxxx>]

The test verifies MMIO writes of various sizes from the guest to the host.

Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/lib/x86_64/tdx.h  | 18 ++++
 .../selftests/kvm/x86_64/tdx_vm_tests.c       | 92 +++++++++++++++++++
 2 files changed, 110 insertions(+)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx.h b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
index 7045d617dd78..17e3649e5729 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/tdx.h
+++ b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
@@ -329,6 +329,24 @@ static inline uint64_t tdvmcall_mmio_read(uint64_t address, uint64_t size, uint6
 	return regs.r10;
 }
 
+/*
+ * Execute MMIO request instruction for write.
+ */
+static inline uint64_t tdvmcall_mmio_write(uint64_t address, uint64_t size, uint64_t data_in)
+{
+	struct kvm_regs regs;
+
+	memset(&regs, 0, sizeof(regs));
+	regs.r11 = TDX_INSTRUCTION_VE_REQUEST_MMIO;
+	regs.r12 = size;
+	regs.r13 = TDX_MMIO_WRITE;
+	regs.r14 = address;
+	regs.r15 = data_in;
+	regs.rcx = 0xFC00;
+	tdcall(&regs);
+	return regs.r10;
+}
+
 /*
  * Reports a 32 bit value from the guest to user space using a TDVM IO call.
  * Data is reported on port TDX_DATA_REPORT_PORT.
diff --git a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
index 963e4feae31a..382119bd444b 100644
--- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
@@ -1082,6 +1082,97 @@ void verify_mmio_reads(void)
 	printf("\t ... PASSED\n");
 }
 
+TDX_GUEST_FUNCTION(guest_mmio_writes)
+{
+	uint64_t ret;
+
+	ret = tdvmcall_mmio_write(MMIO_VALID_ADDRESS, 1, 0x12);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	ret = tdvmcall_mmio_write(MMIO_VALID_ADDRESS, 2, 0x1234);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	ret = tdvmcall_mmio_write(MMIO_VALID_ADDRESS, 4, 0x12345678);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	ret = tdvmcall_mmio_write(MMIO_VALID_ADDRESS, 8, 0x1234567890ABCDEF);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	// Write across page boundary.
+	ret = tdvmcall_mmio_write(PAGE_SIZE - 1, 8, 0);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	tdvmcall_success();
+}
+
+/*
+ * Varifies guest MMIO writes.
+ */
+void verify_mmio_writes(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	uint8_t byte_1;
+	uint16_t byte_2;
+	uint32_t byte_4;
+	uint64_t byte_8;
+
+	printf("Verifying TD MMIO writes:\n");
+	/* Create a TD VM with no memory.*/
+	vm = vm_create_tdx();
+
+	/* Allocate TD guest memory and initialize the TD.*/
+	initialize_td(vm);
+
+	/* Initialize the TD vcpu and copy the test code to the guest memory.*/
+	vcpu = vm_vcpu_add_tdx(vm, 0);
+
+	/* Setup and initialize VM memory */
+	prepare_source_image(vm, guest_mmio_writes,
+			     TDX_FUNCTION_SIZE(guest_mmio_writes), 0);
+	finalize_td_memory(vm);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_MMIO(vcpu, MMIO_VALID_ADDRESS, 1, TDX_MMIO_WRITE);
+	byte_1 = *(uint8_t *)(vcpu->run->mmio.data);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_MMIO(vcpu, MMIO_VALID_ADDRESS, 2, TDX_MMIO_WRITE);
+	byte_2 = *(uint16_t *)(vcpu->run->mmio.data);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_MMIO(vcpu, MMIO_VALID_ADDRESS, 4, TDX_MMIO_WRITE);
+	byte_4 = *(uint32_t *)(vcpu->run->mmio.data);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_MMIO(vcpu, MMIO_VALID_ADDRESS, 8, TDX_MMIO_WRITE);
+	byte_8 = *(uint64_t *)(vcpu->run->mmio.data);
+
+	ASSERT_EQ(byte_1, 0x12);
+	ASSERT_EQ(byte_2, 0x1234);
+	ASSERT_EQ(byte_4, 0x12345678);
+	ASSERT_EQ(byte_8, 0x1234567890ABCDEF);
+
+	vcpu_run(vcpu);
+	ASSERT_EQ(vcpu->run->exit_reason, KVM_EXIT_SYSTEM_EVENT);
+	ASSERT_EQ(vcpu->run->system_event.data[1], TDX_VMCALL_INVALID_OPERAND);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_COMPLETION(vcpu);
+
+	kvm_vm_free(vm);
+	printf("\t ... PASSED\n");
+}
+
 int main(int argc, char **argv)
 {
 	if (!is_tdx_enabled()) {
@@ -1100,6 +1191,7 @@ int main(int argc, char **argv)
 	run_in_new_process(&verify_guest_msr_writes);
 	run_in_new_process(&verify_guest_hlt);
 	run_in_new_process(&verify_mmio_reads);
+	run_in_new_process(&verify_mmio_writes);
 
 	return 0;
 }
-- 
2.37.2.789.g6183377224-goog