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

Sagi Shahar
2022-08-30T22:22:20Z

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@google.com>
---
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