[RFC PATCH v2 14/17] KVM: selftest: TDX: Add TDX CPUID TDVMCALL test

[Sagi Shahar]

This test issues a CPUID TDVMCALL from inside the guest to get the CPUID
values as seen by KVM.

Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/lib/x86_64/tdx.h  |  23 ++++
 .../selftests/kvm/x86_64/tdx_vm_tests.c       | 102 ++++++++++++++++++
 2 files changed, 125 insertions(+)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx.h b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
index 17e3649e5729..3729543a05a3 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/tdx.h
+++ b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
@@ -56,6 +56,7 @@
 
 #define TDX_GET_TD_VM_CALL_INFO 0x10000
 #define TDX_REPORT_FATAL_ERROR 0x10003
+#define TDX_INSTRUCTION_CPUID 10
 #define TDX_INSTRUCTION_HLT 12
 #define TDX_INSTRUCTION_IO 30
 #define TDX_INSTRUCTION_RDMSR 31
@@ -347,6 +348,28 @@ static inline uint64_t tdvmcall_mmio_write(uint64_t address, uint64_t size, uint
 	return regs.r10;
 }
 
+/*
+ * Execute CPUID instruction.
+ */
+static inline uint64_t tdvmcall_cpuid(uint32_t eax, uint32_t ecx,
+				      uint32_t *ret_eax, uint32_t *ret_ebx,
+				      uint32_t *ret_ecx, uint32_t *ret_edx)
+{
+	struct kvm_regs regs;
+
+	memset(&regs, 0, sizeof(regs));
+	regs.r11 = TDX_INSTRUCTION_CPUID;
+	regs.r12 = eax;
+	regs.r13 = ecx;
+	regs.rcx = 0xFC00;
+	tdcall(&regs);
+	*ret_eax = regs.r12;
+	*ret_ebx = regs.r13;
+	*ret_ecx = regs.r14;
+	*ret_edx = regs.r15;
+	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 382119bd444b..934f2f7a5df9 100644
--- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
@@ -459,6 +459,107 @@ void verify_td_cpuid(void)
 	printf("\t ... PASSED\n");
 }
 
+/*
+ * Verifies CPUID TDVMCALL functionality.
+ * The guest will then send the values to userspace using an IO write to be
+ * checked against the expected values.
+ */
+TDX_GUEST_FUNCTION(guest_code_cpuid_tdcall)
+{
+	uint64_t err;
+	uint32_t eax, ebx, ecx, edx;
+
+	// Read CPUID leaf 0x1 from host.
+	err = tdvmcall_cpuid(/*eax=*/1, /*ecx=*/0, &eax, &ebx, &ecx, &edx);
+	if (err)
+		tdvmcall_fatal(err);
+
+	err = tdvm_report_to_user_space(eax);
+	if (err)
+		tdvmcall_fatal(err);
+
+	err = tdvm_report_to_user_space(ebx);
+	if (err)
+		tdvmcall_fatal(err);
+
+	err = tdvm_report_to_user_space(ecx);
+	if (err)
+		tdvmcall_fatal(err);
+
+	err = tdvm_report_to_user_space(edx);
+	if (err)
+		tdvmcall_fatal(err);
+
+	tdvmcall_success();
+}
+
+void verify_td_cpuid_tdcall(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	uint32_t eax, ebx, ecx, edx;
+	struct kvm_cpuid_entry2 *cpuid_entry;
+	struct tdx_cpuid_data cpuid_data;
+	int ret;
+
+	printf("Verifying TD CPUID TDVMCALL:\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_code_cpuid_tdcall,
+			     TDX_FUNCTION_SIZE(guest_code_cpuid_tdcall), 0);
+	finalize_td_memory(vm);
+
+	/* Wait for guest to report CPUID values */
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_IO(vcpu, TDX_DATA_REPORT_PORT, 4, TDX_IO_WRITE);
+	eax = *(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_IO(vcpu, TDX_DATA_REPORT_PORT, 4, TDX_IO_WRITE);
+	ebx = *(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_IO(vcpu, TDX_DATA_REPORT_PORT, 4, TDX_IO_WRITE);
+	ecx = *(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_IO(vcpu, TDX_DATA_REPORT_PORT, 4, TDX_IO_WRITE);
+	edx = *(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_GUEST_COMPLETION(vcpu);
+
+	/* Get KVM CPUIDs for reference */
+	memset(&cpuid_data, 0, sizeof(cpuid_data));
+	cpuid_data.cpuid.nent = KVM_MAX_CPUID_ENTRIES;
+	ret = ioctl(vm->kvm_fd, KVM_GET_SUPPORTED_CPUID, &cpuid_data);
+	TEST_ASSERT(!ret, "KVM_GET_SUPPORTED_CPUID failed\n");
+	cpuid_entry = find_cpuid_entry(cpuid_data, 1, 0);
+	TEST_ASSERT(cpuid_entry, "CPUID entry missing\n");
+
+	ASSERT_EQ(cpuid_entry->eax, eax);
+	// Mask lapic ID when comparing ebx.
+	ASSERT_EQ(cpuid_entry->ebx & ~0xFF000000, ebx & ~0xFF000000);
+	ASSERT_EQ(cpuid_entry->ecx, ecx);
+	ASSERT_EQ(cpuid_entry->edx, edx);
+
+	kvm_vm_free(vm);
+	printf("\t ... PASSED\n");
+}
+
 /*
  * Verifies get_td_vmcall_info functionality.
  */
@@ -1184,6 +1285,7 @@ int main(int argc, char **argv)
 	run_in_new_process(&verify_report_fatal_error);
 	run_in_new_process(&verify_td_ioexit);
 	run_in_new_process(&verify_td_cpuid);
+	run_in_new_process(&verify_td_cpuid_tdcall);
 	run_in_new_process(&verify_get_td_vmcall_info);
 	run_in_new_process(&verify_guest_writes);
 	run_in_new_process(&verify_guest_reads);
-- 
2.37.2.789.g6183377224-goog