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

Sagi Shahar
2022-08-30T22:22:11Z

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

Signed-off-by: Sagi Shahar <sagis@google.com>
---
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