linux-kernel - Re: [PATCH v4 25/28] KVM: TDX: Don't copy "cmd" back to userspace for KVM_TDX

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Message-ID: <6830e97d6481809b4ad9229d32d9a9f8d6062789.camel@intel.com>
Date: Thu, 30 Oct 2025 23:06:09 +0000
From: "Huang, Kai" <kai.huang@...el.com>
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Subject: Re: [PATCH v4 25/28] KVM: TDX: Don't copy "cmd" back to userspace for
 KVM_TDX_CAPABILITIES

On Thu, 2025-10-30 at 13:09 -0700, Sean Christopherson wrote:
> 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@...el.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Kai Huang <kai.huang@...el.com>