[RFC PATCH v5 026/104] KVM: TDX: x86: Add vm ioctl to get TDX systemwide parameters

[isaku.yamahata@xxxxxxxxx]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

Implement a VM-scoped subcomment to get system-wide parameters.  Although
this is system-wide parameters not per-VM, this subcomand is VM-scoped
because
- Device model needs TDX system-wide parameters after creating KVM VM.
- This subcommands requires to initialize TDX module.  For lazy
  initialization of the TDX module, vm-scope ioctl is better.

Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
 arch/x86/include/uapi/asm/kvm.h       | 22 ++++++++++++++
 arch/x86/kvm/vmx/tdx.c                | 41 +++++++++++++++++++++++++++
 tools/arch/x86/include/uapi/asm/kvm.h | 22 ++++++++++++++
 3 files changed, 85 insertions(+)

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 2ad61caf4e0b..70f9be4ea575 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -530,6 +530,8 @@ struct kvm_pmu_event_filter {
 
 /* Trust Domain eXtension sub-ioctl() commands. */
 enum kvm_tdx_cmd_id {
+	KVM_TDX_CAPABILITIES = 0,
+
 	KVM_TDX_CMD_NR_MAX,
 };
 
@@ -539,4 +541,24 @@ struct kvm_tdx_cmd {
 	__u64 data;
 };
 
+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;
+
+	__u32 nr_cpuid_configs;
+	__u32 padding;
+	struct kvm_tdx_cpuid_config cpuid_configs[0];
+};
+
 #endif /* _ASM_X86_KVM_H */
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 8c67444d052a..20b45bb0b032 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -349,6 +349,44 @@ int tdx_vm_init(struct kvm *kvm)
 	return ret;
 }
 
+static int tdx_capabilities(struct kvm *kvm, struct kvm_tdx_cmd *cmd)
+{
+	struct kvm_tdx_capabilities __user *user_caps;
+	struct kvm_tdx_capabilities caps;
+
+	BUILD_BUG_ON(sizeof(struct kvm_tdx_cpuid_config) !=
+		     sizeof(struct tdx_cpuid_config));
+
+	WARN_ON(cmd->id != KVM_TDX_CAPABILITIES);
+	if (cmd->metadata)
+		return -EINVAL;
+
+	user_caps = (void __user *)cmd->data;
+	if (copy_from_user(&caps, user_caps, sizeof(caps)))
+		return -EFAULT;
+
+	if (caps.nr_cpuid_configs < tdx_caps.nr_cpuid_configs)
+		return -E2BIG;
+
+	caps = (struct kvm_tdx_capabilities) {
+		.attrs_fixed0 = tdx_caps.attrs_fixed0,
+		.attrs_fixed1 = tdx_caps.attrs_fixed1,
+		.xfam_fixed0 = tdx_caps.xfam_fixed0,
+		.xfam_fixed1 = tdx_caps.xfam_fixed1,
+		.nr_cpuid_configs = tdx_caps.nr_cpuid_configs,
+		.padding = 0,
+	};
+
+	if (copy_to_user(user_caps, &caps, sizeof(caps)))
+		return -EFAULT;
+	if (copy_to_user(user_caps->cpuid_configs, &tdx_caps.cpuid_configs,
+			 tdx_caps.nr_cpuid_configs *
+			 sizeof(struct tdx_cpuid_config)))
+		return -EFAULT;
+
+	return 0;
+}
+
 int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
 {
 	struct kvm_tdx_cmd tdx_cmd;
@@ -360,6 +398,9 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
 	mutex_lock(&kvm->lock);
 
 	switch (tdx_cmd.id) {
+	case KVM_TDX_CAPABILITIES:
+		r = tdx_capabilities(kvm, &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 2ad61caf4e0b..70f9be4ea575 100644
--- a/tools/arch/x86/include/uapi/asm/kvm.h
+++ b/tools/arch/x86/include/uapi/asm/kvm.h
@@ -530,6 +530,8 @@ struct kvm_pmu_event_filter {
 
 /* Trust Domain eXtension sub-ioctl() commands. */
 enum kvm_tdx_cmd_id {
+	KVM_TDX_CAPABILITIES = 0,
+
 	KVM_TDX_CMD_NR_MAX,
 };
 
@@ -539,4 +541,24 @@ struct kvm_tdx_cmd {
 	__u64 data;
 };
 
+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;
+
+	__u32 nr_cpuid_configs;
+	__u32 padding;
+	struct kvm_tdx_cpuid_config cpuid_configs[0];
+};
+
 #endif /* _ASM_X86_KVM_H */
-- 
2.25.1