Re: [RFC PATCH v5 15/29] KVM: selftests: TDX: Add TDX MSR read/write tests
From: Binbin Wu
Date: Fri Mar 01 2024 - 07:10:13 EST
On 3/1/2024 8:00 PM, Binbin Wu wrote:
On 12/13/2023 4:46 AM, Sagi Shahar wrote:
The test verifies reads and writes for MSR registers with different
access
level.
Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Signed-off-by: Ryan Afranji <afranji@xxxxxxxxxx>
---
.../selftests/kvm/include/x86_64/tdx/tdx.h | 5 +
.../selftests/kvm/lib/x86_64/tdx/tdx.c | 27 +++
.../selftests/kvm/x86_64/tdx_vm_tests.c | 209 ++++++++++++++++++
3 files changed, 241 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 63788012bf94..85ba6aab79a7 100644
--- a/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
+++ b/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
@@ -9,11 +9,16 @@
#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
+
void handle_userspace_tdg_vp_vmcall_exit(struct kvm_vcpu *vcpu);
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 e5a9e13c62e2..88ea6f2a6469 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
@@ -87,3 +87,30 @@ 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 699cba36e9ce..5db3701cc6d9 100644
--- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
@@ -515,6 +515,213 @@ void verify_guest_reads(void)
printf("\t ... PASSED\n");
}
+/*
+ * Define a filter which denies all MSR access except the following:
+ * MSR_X2APIC_APIC_ICR: Allow read/write access (allowed by default)
The default filtering behavior of tdx_msr_test_filter is
KVM_MSR_FILTER_DEFAULT_DENY, and MSR_X2APIC_APIC_ICR is not covered
by any specific range, shouldn't MSR_X2APIC_APIC_ICR be denied by
default?
Sorry, please ignore this comment.
I see the description from the KVM document later:
"x2APIC MSR accesses cannot be filtered (KVM silently ignores filters
that cover any x2APIC MSRs)."
+ * MSR_IA32_MISC_ENABLE: Allow read access
+ * MSR_IA32_POWER_CTL: Allow write access
+ */
+#define MSR_X2APIC_APIC_ICR 0x830
+static u64 tdx_msr_test_allow_bits = 0xFFFFFFFFFFFFFFFF;
+struct kvm_msr_filter tdx_msr_test_filter = {
+ .flags = KVM_MSR_FILTER_DEFAULT_DENY,
+ .ranges = {
+ {
+ .flags = KVM_MSR_FILTER_READ,
+ .nmsrs = 1,
+ .base = MSR_IA32_MISC_ENABLE,
+ .bitmap = (uint8_t *)&tdx_msr_test_allow_bits,
+ }, {
+ .flags = KVM_MSR_FILTER_WRITE,
+ .nmsrs = 1,
+ .base = MSR_IA32_POWER_CTL,
+ .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(MSR_X2APIC_APIC_ICR, &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(MSR_IA32_MISC_ENABLE, &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 MSR_IA32_POWER_CTL is write
only */
+ ret = tdg_vp_vmcall_instruction_rdmsr(MSR_IA32_POWER_CTL, &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 MSR values\n");
+ /* Write arbitrary to the MSRs. */
+ vcpu_set_msr(vcpu, MSR_X2APIC_APIC_ICR, 4);
+ vcpu_set_msr(vcpu, MSR_IA32_MISC_ENABLE, 5);
+ vcpu_set_msr(vcpu, MSR_IA32_POWER_CTL, 6);
+
+ printf("\t ... Running guest\n");
+ td_vcpu_run(vcpu);
+ TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+ data = tdx_test_read_64bit_report_from_guest(vcpu);
+ TEST_ASSERT_EQ(data, 4);
+
+ td_vcpu_run(vcpu);
+ TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+ data = tdx_test_read_64bit_report_from_guest(vcpu);
+ TEST_ASSERT_EQ(data, 5);
+
+ td_vcpu_run(vcpu);
+ TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+ data = tdx_test_read_64bit_report_from_guest(vcpu);
+ TEST_ASSERT_EQ(data, TDG_VP_VMCALL_INVALID_OPERAND);
+
+ td_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(MSR_X2APIC_APIC_ICR, 4);
+ if (ret)
+ tdx_test_fatal(ret);
+
+ /* We expect this call to fail since MSR_IA32_MISC_ENABLE is
read only */
+ ret = tdg_vp_vmcall_instruction_wrmsr(MSR_IA32_MISC_ENABLE, 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(MSR_IA32_POWER_CTL, 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 MSR_IA32_MISC_ENABLE should trigger an exit */
+ td_vcpu_run(vcpu);
+ TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+ data = tdx_test_read_64bit_report_from_guest(vcpu);
+ TEST_ASSERT_EQ(data, TDG_VP_VMCALL_INVALID_OPERAND);
+
+ td_vcpu_run(vcpu);
+ TDX_TEST_ASSERT_SUCCESS(vcpu);
+
+ printf("\t ... Verifying MSR values writen by guest\n");
+
+ TEST_ASSERT_EQ(vcpu_get_msr(vcpu, MSR_X2APIC_APIC_ICR), 4);
+ TEST_ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_MISC_ENABLE), 0x1800);
+ TEST_ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_POWER_CTL), 6);
+
+ kvm_vm_free(vm);
+ printf("\t ... PASSED\n");
+}
+
+
int main(int argc, char **argv)
{
setbuf(stdout, NULL);
@@ -531,6 +738,8 @@ 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;
}