[RFC PATCH v2 07/17] KVM: selftest: TDX: Add basic get_td_vmcall_info test

Sagi Shahar
2022-08-30T22:20:58Z

The test calls get_td_vmcall_info from the guest and verifies the
expected returned values.

Signed-off-by: Sagi Shahar <sagis@google.com>
---
tools/testing/selftests/kvm/lib/x86_64/tdx.h | 43 +++++++
.../selftests/kvm/x86_64/tdx_vm_tests.c | 107 ++++++++++++++++++
2 files changed, 150 insertions(+)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx.h b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
index a28d15417d3e..39b000118e26 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/tdx.h
+++ b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
@@ -51,6 +51,7 @@
#define _PAGE_RW (1UL<<1) /* writeable */
#define _PAGE_PS (1UL<<7) /* page size bit*/

+#define TDX_GET_TD_VM_CALL_INFO 0x10000
#define TDX_REPORT_FATAL_ERROR 0x10003
#define TDX_INSTRUCTION_IO 30

@@ -232,6 +233,28 @@ static inline void tdvmcall_fatal(uint64_t error_code)
tdcall(&regs);
}

+/*
+ * Get td vmcall info.
+ * Used to help request the host VMM enumerate which TDG.VP.VMCALLs are supported.
+ * Returns return in r10 code and leaf-specific output in r11-r14.
+ */
+static inline uint64_t tdvmcall_get_td_vmcall_info(uint64_t *r11, uint64_t *r12,
+ uint64_t *r13, uint64_t *r14)
+{
+ struct kvm_regs regs;
+
+ memset(&regs, 0, sizeof(regs));
+ regs.r11 = TDX_GET_TD_VM_CALL_INFO;
+ regs.r12 = 0;
+ regs.rcx = 0x1C00;
+ tdcall(&regs);
+ *r11 = regs.r11;
+ *r12 = regs.r12;
+ *r13 = regs.r13;
+ *r14 = regs.r14;
+ 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.
@@ -244,6 +267,26 @@ static inline uint64_t tdvm_report_to_user_space(uint32_t data)
return tdvmcall_io(TDX_DATA_REPORT_PORT, /*size=*/4, TDX_IO_WRITE, &data_64);
}

+/*
+ * Reports a 64 bit value from the guest to user space using a TDVM IO call.
+ * Data is reported on port TDX_DATA_REPORT_PORT.
+ * Data is sent to host in 2 calls. LSB is sent (and needs to be read) first.
+ */
+static inline uint64_t tdvm_report_64bit_to_user_space(uint64_t data)
+{
+ uint64_t err;
+ uint64_t data_lo = data & 0xFFFFFFFF;
+ uint64_t data_hi = (data >> 32) & 0xFFFFFFFF;
+
+ err = tdvmcall_io(TDX_DATA_REPORT_PORT, /*size=*/4, TDX_IO_WRITE,
+ &data_lo);
+ if (err)
+ return err;
+
+ return tdvmcall_io(TDX_DATA_REPORT_PORT, /*size=*/4, TDX_IO_WRITE,
+ &data_hi);
+}
+
#define TDX_FUNCTION_SIZE(name) ((uint64_t)&__stop_sec_ ## name -\
(uint64_t)&__start_sec_ ## name) \

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 3f51f936ea5a..cf8260db1f5b 100644
--- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
@@ -53,6 +53,25 @@
(VCPU)->run->system_event.data[1]); \
} while (0)

+static uint64_t read_64bit_from_guest(struct kvm_vcpu *vcpu, uint64_t port)
+{
+ uint32_t lo, hi;
+ uint64_t res;
+
+ CHECK_IO(vcpu, port, 4, TDX_IO_WRITE);
+ lo = *(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+ vcpu_run(vcpu);
+
+ CHECK_IO(vcpu, port, 4, TDX_IO_WRITE);
+ hi = *(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+ res = hi;
+ res = (res << 32) | lo;
+ return res;
+}
+
+
/*
* There might be multiple tests we are running and if one test fails, it will
* prevent the subsequent tests to run due to how tests are failing with
@@ -383,6 +402,93 @@ void verify_td_cpuid(void)
printf("\t ... PASSED\n");
}

+/*
+ * Verifies get_td_vmcall_info functionality.
+ */
+TDX_GUEST_FUNCTION(guest_code_get_td_vmcall_info)
+{
+ uint64_t err;
+ uint64_t r11, r12, r13, r14;
+
+ err = tdvmcall_get_td_vmcall_info(&r11, &r12, &r13, &r14);
+ if (err)
+ tdvmcall_fatal(err);
+
+ err = tdvm_report_64bit_to_user_space(r11);
+ if (err)
+ tdvmcall_fatal(err);
+
+ err = tdvm_report_64bit_to_user_space(r12);
+ if (err)
+ tdvmcall_fatal(err);
+
+ err = tdvm_report_64bit_to_user_space(r13);
+ if (err)
+ tdvmcall_fatal(err);
+
+ err = tdvm_report_64bit_to_user_space(r14);
+ if (err)
+ tdvmcall_fatal(err);
+
+ tdvmcall_success();
+}
+
+void verify_get_td_vmcall_info(void)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vm *vm;
+ uint64_t r11, r12, r13, r14;
+
+ printf("Verifying TD get vmcall info:\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_get_td_vmcall_info,
+ TDX_FUNCTION_SIZE(guest_code_get_td_vmcall_info),
+ 0);
+ finalize_td_memory(vm);
+
+ /* Wait for guest to report r11 value */
+ vcpu_run(vcpu);
+ CHECK_GUEST_FAILURE(vcpu);
+ r11 = read_64bit_from_guest(vcpu, TDX_DATA_REPORT_PORT);
+
+ /* Wait for guest to report r12 value */
+ vcpu_run(vcpu);
+ CHECK_GUEST_FAILURE(vcpu);
+ r12 = read_64bit_from_guest(vcpu, TDX_DATA_REPORT_PORT);
+
+ /* Wait for guest to report r13 value */
+ vcpu_run(vcpu);
+ CHECK_GUEST_FAILURE(vcpu);
+ r13 = read_64bit_from_guest(vcpu, TDX_DATA_REPORT_PORT);
+
+ /* Wait for guest to report r14 value */
+ vcpu_run(vcpu);
+ CHECK_GUEST_FAILURE(vcpu);
+ r14 = read_64bit_from_guest(vcpu, TDX_DATA_REPORT_PORT);
+
+ ASSERT_EQ(r11, 0);
+ ASSERT_EQ(r12, 0);
+ ASSERT_EQ(r13, 0);
+ ASSERT_EQ(r14, 0);
+
+ /* Wait for guest to complete execution */
+ vcpu_run(vcpu);
+ CHECK_GUEST_FAILURE(vcpu);
+ CHECK_GUEST_COMPLETION(vcpu);
+
+ kvm_vm_free(vm);
+ printf("\t ... PASSED\n");
+}
+
int main(int argc, char **argv)
{
if (!is_tdx_enabled()) {
@@ -394,6 +500,7 @@ 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_get_td_vmcall_info);

return 0;
}
--
2.37.2.789.g6183377224-goog