[PATCH v18 022/121] KVM: TDX: x86: Add ioctl to get TDX systemwide parameters

[isaku.yamahata@xxxxxxxxx]

From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>

Implement an ioctl to get system-wide parameters for TDX.  Although the
function is systemwide, vm scoped mem_enc ioctl works for userspace VMM
like qemu and device scoped version is not define, re-use vm scoped
mem_enc.

Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
v18:
- drop the use of tdhsysinfo_struct and TDH.SYS.INFO, use TDH.SYS.RD().
  For that, dynamically allocate/free tdx_info.
- drop the change of tools/arch/x86/include/uapi/asm/kvm.h.

v14 -> v15:
- ABI change: added supported_gpaw and reserved area.
---
 arch/x86/include/uapi/asm/kvm.h | 17 ++++++++++
 arch/x86/kvm/vmx/tdx.c          | 56 +++++++++++++++++++++++++++++++++
 arch/x86/kvm/vmx/tdx.h          |  3 ++
 3 files changed, 76 insertions(+)

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 9ea46d143bef..e28189c81691 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -604,4 +604,21 @@ struct kvm_tdx_cpuid_config {
 	__u32 edx;
 };
 
+/* supported_gpaw */
+#define TDX_CAP_GPAW_48	(1 << 0)
+#define TDX_CAP_GPAW_52	(1 << 1)
+
+struct kvm_tdx_capabilities {
+	__u64 attrs_fixed0;
+	__u64 attrs_fixed1;
+	__u64 xfam_fixed0;
+	__u64 xfam_fixed1;
+	__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 56655e6bfd5e..8c463407f8a8 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_arch.h"
 #include "tdx.h"
 
@@ -99,6 +100,58 @@ struct tdx_info {
 /* Info about the TDX module. */
 static struct tdx_info *tdx_info;
 
+static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
+{
+	struct kvm_tdx_capabilities __user *user_caps;
+	struct kvm_tdx_capabilities *caps = NULL;
+	int ret = 0;
+
+	if (cmd->flags)
+		return -EINVAL;
+
+	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 < tdx_info->num_cpuid_config) {
+		ret = -E2BIG;
+		goto out;
+	}
+
+	*caps = (struct kvm_tdx_capabilities) {
+		.attrs_fixed0 = tdx_info->attributes_fixed0,
+		.attrs_fixed1 = tdx_info->attributes_fixed1,
+		.xfam_fixed0 = tdx_info->xfam_fixed0,
+		.xfam_fixed1 = tdx_info->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 = tdx_info->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, &tdx_info->cpuid_configs,
+			 tdx_info->num_cpuid_config *
+			 sizeof(tdx_info->cpuid_configs[0]))) {
+		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;
@@ -112,6 +165,9 @@ 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/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
index 473013265bd8..22c0b57f69ca 100644
--- a/arch/x86/kvm/vmx/tdx.h
+++ b/arch/x86/kvm/vmx/tdx.h
@@ -3,6 +3,9 @@
 #define __KVM_X86_TDX_H
 
 #ifdef CONFIG_INTEL_TDX_HOST
+
+#include "tdx_ops.h"
+
 struct kvm_tdx {
 	struct kvm kvm;
 	/* TDX specific members follow. */
-- 
2.25.1