Re: [PATCH v8 18/30] KVM: selftests: TDX: Add TDX MMIO reads test

On 8/8/2025 4:16 AM, Sagi Shahar wrote: [...]

diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c index 8c3b6802c37e..f92ddda2d1ac 100644 --- a/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c +++ b/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c @@ -31,6 +31,25 @@ void tdx_test_assert_io(struct kvm_vcpu *vcpu, uint16_t port, uint8_t size, vcpu->run->io.direction); } +void tdx_test_assert_mmio(struct kvm_vcpu *vcpu, uint64_t phys_addr,

• 	  uint32_t size, uint8_t is_write)
  

+{

• TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_MMIO,

•     "Got exit_reason other than KVM_EXIT_MMIO: %u (%s)\n",
  

•     vcpu->run->exit_reason,
  

•     exit_reason_str(vcpu->run->exit_reason));
  

• TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_MMIO &&

It's already checked above.

•     vcpu->run->mmio.phys_addr == phys_addr &&
  

•     vcpu->run->mmio.len == size &&
  

•     vcpu->run->mmio.is_write == is_write,
  

•     "Got an unexpected MMIO exit values: %u (%s) %llu %u %u\n",
  

•     vcpu->run->exit_reason,
  

•     exit_reason_str(vcpu->run->exit_reason),
  

•     vcpu->run->mmio.phys_addr, vcpu->run->mmio.len,
  

•     vcpu->run->mmio.is_write);
  

+}

• void tdx_run(struct kvm_vcpu *vcpu) { td_vcpu_run(vcpu);

diff --git a/tools/testing/selftests/kvm/x86/tdx_vm_test.c b/tools/testing/selftests/kvm/x86/tdx_vm_test.c index 720ef5e87071..563f1025c8a3 100644 --- a/tools/testing/selftests/kvm/x86/tdx_vm_test.c +++ b/tools/testing/selftests/kvm/x86/tdx_vm_test.c @@ -719,6 +719,91 @@ void verify_guest_hlt(void) _verify_guest_hlt(0); } +/* Pick any address that was not mapped into the guest to test MMIO */ +#define TDX_MMIO_TEST_ADDR 0x200000000 +#define MMIO_SYNC_VALUE 0x42

+void guest_mmio_reads(void) +{

• uint64_t mmio_test_addr = TDX_MMIO_TEST_ADDR | tdx_s_bit;
• uint64_t data;
• uint64_t ret;
• ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 1, &data);
• tdx_assert_error(ret);
• if (data != 0x12)

• tdx_test_fatal(1);
  

• ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 2, &data);
• tdx_assert_error(ret);
• if (data != 0x1234)

• tdx_test_fatal(2);
  

• ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 4, &data);
• tdx_assert_error(ret);
• if (data != 0x12345678)

• tdx_test_fatal(4);
  

• ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 8, &data);
• tdx_assert_error(ret);
• if (data != 0x1234567890ABCDEF)

• tdx_test_fatal(8);
  

• /* Make sure host and guest are synced to the same point of execution */
• tdx_test_report_to_user_space(MMIO_SYNC_VALUE);

Is this step necessary?

• /* Read an invalid number of bytes. */
• ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 10, &data);
• tdx_assert_error(ret);
• tdx_test_success();

+}

+/*

• • Verifies guest MMIO reads.
• */

+void verify_mmio_reads(void) +{

• struct kvm_vcpu *vcpu;
• struct kvm_vm *vm;
• vm = td_create();
• td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
• vcpu = td_vcpu_add(vm, 0, guest_mmio_reads);
• td_finalize(vm);
• printf("Verifying TD MMIO reads:\n");
• tdx_run(vcpu);
• tdx_test_assert_mmio(vcpu, TDX_MMIO_TEST_ADDR, 1, MMIO_READ);
• *(uint8_t *)vcpu->run->mmio.data = 0x12;
• tdx_run(vcpu);
• tdx_test_assert_mmio(vcpu, TDX_MMIO_TEST_ADDR, 2, MMIO_READ);
• *(uint16_t *)vcpu->run->mmio.data = 0x1234;
• tdx_run(vcpu);
• tdx_test_assert_mmio(vcpu, TDX_MMIO_TEST_ADDR, 4, MMIO_READ);
• *(uint32_t *)vcpu->run->mmio.data = 0x12345678;
• tdx_run(vcpu);
• tdx_test_assert_mmio(vcpu, TDX_MMIO_TEST_ADDR, 8, MMIO_READ);
• *(uint64_t *)vcpu->run->mmio.data = 0x1234567890ABCDEF;
• tdx_run(vcpu);
• TEST_ASSERT_EQ(tdx_test_read_report_from_guest(vcpu), MMIO_SYNC_VALUE);
• td_vcpu_run(vcpu);
• TEST_ASSERT_EQ(vcpu->run->exit_reason, KVM_EXIT_SYSTEM_EVENT);
• TEST_ASSERT_EQ(vcpu->run->system_event.data[12], TDG_VP_VMCALL_INVALID_OPERAND);
• tdx_run(vcpu);
• tdx_test_assert_success(vcpu);
• kvm_vm_free(vm);
• printf("\t ... PASSED\n");

+}

• int main(int argc, char **argv) { ksft_print_header();

@@ -726,7 +811,7 @@ 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(10);

• ksft_set_plan(11); ksft_test_result(!run_in_new_process(&verify_td_lifecycle), "verify_td_lifecycle\n"); ksft_test_result(!run_in_new_process(&verify_report_fatal_error),

@@ -747,6 +832,8 @@ int main(int argc, char **argv) "verify_guest_msr_reads\n"); ksft_test_result(!run_in_new_process(&verify_guest_hlt), "verify_guest_hlt\n");

• ksft_test_result(!run_in_new_process(&verify_mmio_reads),

• 	 "verify_mmio_reads\n");
  

ksft_finished(); return 0;