diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 615fb60b3717..3fbd43d5177b 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -593,4 +593,28 @@ struct kvm_tdx_cmd {
 	__u64 error;
 };
 
+struct kvm_tdx_cpuid_config {
+	__u32 leaf;
+	__u32 sub_leaf;
+	__u32 eax;
+	__u32 ebx;
+	__u32 ecx;
+	__u32 edx;
+};
+
+struct kvm_tdx_capabilities {
+	__u64 attrs_fixed0;
+	__u64 attrs_fixed1;
+	__u64 xfam_fixed0;
+	__u64 xfam_fixed1;
+#define TDX_CAP_GPAW_48	(1 << 0)
+#define TDX_CAP_GPAW_52	(1 << 1)
+	__u32 supported_gpaw;
+	__u32 padding;
+	__u64 reserved[251];
+
+	__u32 nr_cpuid_configs;
+	struct kvm_tdx_cpuid_config cpuid_configs[];
+};
+
 #endif /* _ASM_X86_KVM_H */
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index ead229e34813..f9e80582865d 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -6,6 +6,7 @@
 #include "capabilities.h"
 #include "x86_ops.h"
 #include "x86.h"
+#include "mmu.h"
 #include "tdx.h"
 
 #undef pr_fmt
@@ -16,6 +17,66 @@
 		offsetof(struct tdsysinfo_struct, cpuid_configs))	\
 		/ sizeof(struct tdx_cpuid_config))
 
+static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
+{
+	struct kvm_tdx_capabilities __user *user_caps;
+	const struct tdsysinfo_struct *tdsysinfo;
+	struct kvm_tdx_capabilities *caps = NULL;
+	int ret = 0;
+
+	BUILD_BUG_ON(sizeof(struct kvm_tdx_cpuid_config) !=
+		     sizeof(struct tdx_cpuid_config));
+
+	if (cmd->flags)
+		return -EINVAL;
+
+	tdsysinfo = tdx_get_sysinfo();
+	if (!tdsysinfo)
+		return -EOPNOTSUPP;
+
+	caps = kmalloc(sizeof(*caps), GFP_KERNEL);
+	if (!caps)
+		return -ENOMEM;
+
+	user_caps = (void __user *)cmd->data;
+	if (copy_from_user(caps, user_caps, sizeof(*caps))) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	if (caps->nr_cpuid_configs < tdsysinfo->num_cpuid_config) {
+		ret = -E2BIG;
+		goto out;
+	}
+
+	*caps = (struct kvm_tdx_capabilities) {
+		.attrs_fixed0 = tdsysinfo->attributes_fixed0,
+		.attrs_fixed1 = tdsysinfo->attributes_fixed1,
+		.xfam_fixed0 = tdsysinfo->xfam_fixed0,
+		.xfam_fixed1 = tdsysinfo->xfam_fixed1,
+		.supported_gpaw = TDX_CAP_GPAW_48 |
+		(kvm_get_shadow_phys_bits() >= 52 &&
+		 cpu_has_vmx_ept_5levels()) ? TDX_CAP_GPAW_52 : 0,
+		.nr_cpuid_configs = tdsysinfo->num_cpuid_config,
+		.padding = 0,
+	};
+
+	if (copy_to_user(user_caps, caps, sizeof(*caps))) {
+		ret = -EFAULT;
+		goto out;
+	}
+	if (copy_to_user(user_caps->cpuid_configs, &tdsysinfo->cpuid_configs,
+			 tdsysinfo->num_cpuid_config *
+			 sizeof(struct tdx_cpuid_config))) {
+		ret = -EFAULT;
+	}
+
+out:
+	/* kfree() accepts NULL. */
+	kfree(caps);
+	return ret;
+}
+
 int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
 {
 	struct kvm_tdx_cmd tdx_cmd;
@@ -29,6 +90,9 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
 	mutex_lock(&kvm->lock);
 
 	switch (tdx_cmd.id) {
+	case KVM_TDX_CAPABILITIES:
+		r = tdx_get_capabilities(&tdx_cmd);
+		break;
 	default:
 		r = -EINVAL;
 		goto out;
diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
index 1a6a1f987949..7a08723e99e2 100644
--- a/tools/arch/x86/include/uapi/asm/kvm.h
+++ b/tools/arch/x86/include/uapi/asm/kvm.h
@@ -562,4 +562,56 @@ struct kvm_pmu_event_filter {
 /* x86-specific KVM_EXIT_HYPERCALL flags. */
 #define KVM_EXIT_HYPERCALL_LONG_MODE	BIT(0)
 
+/* Trust Domain eXtension sub-ioctl() commands. */
+enum kvm_tdx_cmd_id {
+	KVM_TDX_CAPABILITIES = 0,
+
+	KVM_TDX_CMD_NR_MAX,
+};
+
+struct kvm_tdx_cmd {
+	/* enum kvm_tdx_cmd_id */
+	__u32 id;
+	/* flags for sub-commend. If sub-command doesn't use this, set zero. */
+	__u32 flags;
+	/*
+	 * data for each sub-command. An immediate or a pointer to the actual
+	 * data in process virtual address.  If sub-command doesn't use it,
+	 * set zero.
+	 */
+	__u64 data;
+	/*
+	 * Auxiliary error code.  The sub-command may return TDX SEAMCALL
+	 * status code in addition to -Exxx.
+	 * Defined for consistency with struct kvm_sev_cmd.
+	 */
+	__u64 error;
+	/* Reserved: Defined for consistency with struct kvm_sev_cmd. */
+	__u64 unused;
+};
+
+struct kvm_tdx_cpuid_config {
+	__u32 leaf;
+	__u32 sub_leaf;
+	__u32 eax;
+	__u32 ebx;
+	__u32 ecx;
+	__u32 edx;
+};
+
+struct kvm_tdx_capabilities {
+	__u64 attrs_fixed0;
+	__u64 attrs_fixed1;
+	__u64 xfam_fixed0;
+	__u64 xfam_fixed1;
+#define TDX_CAP_GPAW_48		(1 << 0)
+#define TDX_CAP_GPAW_52		(1 << 1)
+	__u32 supported_gpaw;
+	__u32 padding;
+	__u64 reserved[251];
+
+	__u32 nr_cpuid_configs;
+	struct kvm_tdx_cpuid_config cpuid_configs[];
+};
+
 #endif /* _ASM_X86_KVM_H */
