[PATCH v4 25/28] KVM: TDX: Don't copy "cmd" back to userspace for KVM_TDX_CAPABILITIES

[Sean Christopherson]

Don't copy the kvm_tdx_cmd structure back to userspace when handling
KVM_TDX_CAPABILITIES, as tdx_get_capabilities() doesn't modify hw_error or
any other fields.

Opportunistically hoist the call to tdx_get_capabilities() outside of the
kvm->lock critical section, as getting the capabilities doesn't touch the
VM in any way, e.g. doesn't even take @kvm.

Suggested-by: Kai Huang <kai.huang at intel.com>
Signed-off-by: Sean Christopherson <seanjc at google.com>
---
 arch/x86/kvm/vmx/tdx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 037429964fd7..57dfddd2a6cf 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -2806,12 +2806,12 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
 	if (r)
 		return r;
 
+	if (tdx_cmd.id == KVM_TDX_CAPABILITIES)
+		return tdx_get_capabilities(&tdx_cmd);
+
 	guard(mutex)(&kvm->lock);
 
 	switch (tdx_cmd.id) {
-	case KVM_TDX_CAPABILITIES:
-		r = tdx_get_capabilities(&tdx_cmd);
-		break;
 	case KVM_TDX_INIT_VM:
 		r = tdx_td_init(kvm, &tdx_cmd);
 		break;
-- 
2.51.1.930.gacf6e81ea2-goog