[RFC PATCH v3 16/31] KVM: selftests: TDX: Add TDX MSR read/write tests

Ackerley Tng
2023-01-21T00:18:30Z

From: Sagi Shahar <sagis@google.com>

The test verifies reads and writes for MSR registers with different access
level.

Signed-off-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
Changes RFCv2 -> RFCv3
+ Fixed typo in MTTR->MTRR
---
.../selftests/kvm/include/x86_64/tdx/tdx.h | 4 +
.../selftests/kvm/lib/x86_64/tdx/tdx.c | 27 +++
.../selftests/kvm/x86_64/tdx_vm_tests.c | 217 ++++++++++++++++++
3 files changed, 248 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h b/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
index 37ad16943e299..fbac1951cfe35 100644
--- a/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
+++ b/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
@@ -8,11 +8,15 @@
#define TDG_VP_VMCALL_REPORT_FATAL_ERROR 0x10003

#define TDG_VP_VMCALL_INSTRUCTION_IO 30
+#define TDG_VP_VMCALL_INSTRUCTION_RDMSR 31
+#define TDG_VP_VMCALL_INSTRUCTION_WRMSR 32

uint64_t tdg_vp_vmcall_instruction_io(uint64_t port, uint64_t size,
uint64_t write, uint64_t *data);
void tdg_vp_vmcall_report_fatal_error(uint64_t error_code, uint64_t data_gpa);
uint64_t tdg_vp_vmcall_get_td_vmcall_info(uint64_t *r11, uint64_t *r12,
uint64_t *r13, uint64_t *r14);
+uint64_t tdg_vp_vmcall_instruction_rdmsr(uint64_t index, uint64_t *ret_value);
+uint64_t tdg_vp_vmcall_instruction_wrmsr(uint64_t index, uint64_t value);

#endif // SELFTEST_TDX_TDX_H
diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
index 7254d61515db2..43088d6f40b50 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
@@ -66,3 +66,30 @@ uint64_t tdg_vp_vmcall_get_td_vmcall_info(uint64_t *r11, uint64_t *r12,

return ret;
}
+
+uint64_t tdg_vp_vmcall_instruction_rdmsr(uint64_t index, uint64_t *ret_value)
+{
+ uint64_t ret;
+ struct tdx_hypercall_args args = {
+ .r11 = TDG_VP_VMCALL_INSTRUCTION_RDMSR,
+ .r12 = index,
+ };
+
+ ret = __tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT);
+
+ if (ret_value)
+ *ret_value = args.r11;
+
+ return ret;
+}
+
+uint64_t tdg_vp_vmcall_instruction_wrmsr(uint64_t index, uint64_t value)
+{
+ struct tdx_hypercall_args args = {
+ .r11 = TDG_VP_VMCALL_INSTRUCTION_WRMSR,
+ .r12 = index,
+ .r13 = value,
+ };
+
+ return __tdx_hypercall(&args, 0);
+}
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 71aa4e5907a05..65ca1ec2a6e82 100644
--- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
@@ -514,6 +514,221 @@ void verify_guest_reads(void)
printf("\t ... PASSED\n");
}

+/*
+ * Define a filter which denies all MSR access except the following:
+ * MTTR_BASE_0: Allow read/write access
+ * MTTR_BASE_1: Allow read access
+ * MTTR_BASE_2: Allow write access
+ */
+static u64 tdx_msr_test_allow_bits = 0xFFFFFFFFFFFFFFFF;
+#define MTTR_BASE_0 (0x200)
+#define MTTR_BASE_1 (0x202)
+#define MTTR_BASE_2 (0x204)
+struct kvm_msr_filter tdx_msr_test_filter = {
+ .flags = KVM_MSR_FILTER_DEFAULT_DENY,
+ .ranges = {
+ {
+ .flags = KVM_MSR_FILTER_READ |
+ KVM_MSR_FILTER_WRITE,
+ .nmsrs = 1,
+ .base = MTTR_BASE_0,
+ .bitmap = (uint8_t *)&tdx_msr_test_allow_bits,
+ }, {
+ .flags = KVM_MSR_FILTER_READ,
+ .nmsrs = 1,
+ .base = MTTR_BASE_1,
+ .bitmap = (uint8_t *)&tdx_msr_test_allow_bits,
+ }, {
+ .flags = KVM_MSR_FILTER_WRITE,
+ .nmsrs = 1,
+ .base = MTTR_BASE_2,
+ .bitmap = (uint8_t *)&tdx_msr_test_allow_bits,
+ },
+ },
+};
+
+/*
+ * Verifies MSR read functionality.
+ */
+void guest_msr_read(void)
+{
+ uint64_t data;
+ uint64_t ret;
+
+ ret = tdg_vp_vmcall_instruction_rdmsr(MTTR_BASE_0, &data);
+ if (ret)
+ tdx_test_fatal(ret);
+
+ ret = tdx_test_report_64bit_to_user_space(data);
+ if (ret)
+ tdx_test_fatal(ret);
+
+ ret = tdg_vp_vmcall_instruction_rdmsr(MTTR_BASE_1, &data);
+ if (ret)
+ tdx_test_fatal(ret);
+
+ ret = tdx_test_report_64bit_to_user_space(data);
+ if (ret)
+ tdx_test_fatal(ret);
+
+ /* We expect this call to fail since MTTR_BASE_2 is write only */
+ ret = tdg_vp_vmcall_instruction_rdmsr(MTTR_BASE_2, &data);
+ if (ret) {
+ ret = tdx_test_report_64bit_to_user_space(ret);
+ if (ret)
+ tdx_test_fatal(ret);
+ } else {
+ tdx_test_fatal(-99);
+ }
+
+ tdx_test_success();
+}
+
+void verify_guest_msr_reads(void)
+{
+ struct kvm_vm *vm;
+ struct kvm_vcpu *vcpu;
+
+ uint64_t data;
+ int ret;
+
+ vm = td_create();
+ td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
+
+ /*
+ * Set explicit MSR filter map to control access to the MSR registers
+ * used in the test.
+ */
+ printf("\t ... Setting test MSR filter\n");
+ ret = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
+ TEST_ASSERT(ret, "KVM_CAP_X86_USER_SPACE_MSR is unavailable");
+ vm_enable_cap(vm, KVM_CAP_X86_USER_SPACE_MSR, KVM_MSR_EXIT_REASON_FILTER);
+
+ ret = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
+ TEST_ASSERT(ret, "KVM_CAP_X86_MSR_FILTER is unavailable");
+
+ ret = ioctl(vm->fd, KVM_X86_SET_MSR_FILTER, &tdx_msr_test_filter);
+ TEST_ASSERT(ret == 0,
+ "KVM_X86_SET_MSR_FILTER failed, ret: %i errno: %i (%s)",
+ ret, errno, strerror(errno));
+
+ vcpu = td_vcpu_add(vm, 0, guest_msr_read);
+ td_finalize(vm);
+
+ printf("Verifying guest msr reads:\n");
+
+ printf("\t ... Setting test MTTR values\n");
+ /* valid values for mtrr type are 0, 1, 4, 5, 6 */
+ vcpu_set_msr(vcpu, MTTR_BASE_0, 4);
+ vcpu_set_msr(vcpu, MTTR_BASE_1, 5);
+ vcpu_set_msr(vcpu, MTTR_BASE_2, 6);
+
+ printf("\t ... Running guest\n");
+ vcpu_run(vcpu);
+ TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+ data = tdx_test_read_64bit_report_from_guest(vcpu);
+ ASSERT_EQ(data, 4);
+
+ vcpu_run(vcpu);
+ TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+ data = tdx_test_read_64bit_report_from_guest(vcpu);
+ ASSERT_EQ(data, 5);
+
+ vcpu_run(vcpu);
+ TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+ data = tdx_test_read_64bit_report_from_guest(vcpu);
+ ASSERT_EQ(data, TDG_VP_VMCALL_INVALID_OPERAND);
+
+ vcpu_run(vcpu);
+ TDX_TEST_ASSERT_SUCCESS(vcpu);
+
+ kvm_vm_free(vm);
+ printf("\t ... PASSED\n");
+}
+
+/*
+ * Verifies MSR write functionality.
+ */
+void guest_msr_write(void)
+{
+ uint64_t ret;
+
+ ret = tdg_vp_vmcall_instruction_wrmsr(MTTR_BASE_0, 4);
+ if (ret)
+ tdx_test_fatal(ret);
+
+ /* We expect this call to fail since MTTR_BASE_1 is read only */
+ ret = tdg_vp_vmcall_instruction_wrmsr(MTTR_BASE_1, 5);
+ if (ret) {
+ ret = tdx_test_report_64bit_to_user_space(ret);
+ if (ret)
+ tdx_test_fatal(ret);
+ } else {
+ tdx_test_fatal(-99);
+ }
+
+
+ ret = tdg_vp_vmcall_instruction_wrmsr(MTTR_BASE_2, 6);
+ if (ret)
+ tdx_test_fatal(ret);
+
+ tdx_test_success();
+}
+
+void verify_guest_msr_writes(void)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vm *vm;
+
+ uint64_t data;
+ int ret;
+
+ vm = td_create();
+ td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
+
+ /*
+ * Set explicit MSR filter map to control access to the MSR registers
+ * used in the test.
+ */
+ printf("\t ... Setting test MSR filter\n");
+ ret = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
+ TEST_ASSERT(ret, "KVM_CAP_X86_USER_SPACE_MSR is unavailable");
+ vm_enable_cap(vm, KVM_CAP_X86_USER_SPACE_MSR, KVM_MSR_EXIT_REASON_FILTER);
+
+ ret = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
+ TEST_ASSERT(ret, "KVM_CAP_X86_MSR_FILTER is unavailable");
+
+ ret = ioctl(vm->fd, KVM_X86_SET_MSR_FILTER, &tdx_msr_test_filter);
+ TEST_ASSERT(ret == 0,
+ "KVM_X86_SET_MSR_FILTER failed, ret: %i errno: %i (%s)",
+ ret, errno, strerror(errno));
+
+ vcpu = td_vcpu_add(vm, 0, guest_msr_write);
+ td_finalize(vm);
+
+ printf("Verifying guest msr writes:\n");
+
+ printf("\t ... Running guest\n");
+ /* Only the write to MTTR_BASE_1 should trigger an exit */
+ vcpu_run(vcpu);
+ TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+ data = tdx_test_read_64bit_report_from_guest(vcpu);
+ ASSERT_EQ(data, TDG_VP_VMCALL_INVALID_OPERAND);
+
+ vcpu_run(vcpu);
+ TDX_TEST_ASSERT_SUCCESS(vcpu);
+
+ printf("\t ... Verifying MTTR values writen by guest\n");
+
+ ASSERT_EQ(vcpu_get_msr(vcpu, MTTR_BASE_0), 4);
+ ASSERT_EQ(vcpu_get_msr(vcpu, MTTR_BASE_1), 0);
+ ASSERT_EQ(vcpu_get_msr(vcpu, MTTR_BASE_2), 6);
+
+ kvm_vm_free(vm);
+ printf("\t ... PASSED\n");
+}
+
+
int main(int argc, char **argv)
{
setbuf(stdout, NULL);
@@ -530,6 +745,8 @@ int main(int argc, char **argv)
run_in_new_process(&verify_get_td_vmcall_info);
run_in_new_process(&verify_guest_writes);
run_in_new_process(&verify_guest_reads);
+ run_in_new_process(&verify_guest_msr_writes);
+ run_in_new_process(&verify_guest_msr_reads);

return 0;
}
--
2.39.0.246.g2a6d74b583-goog