linux-kernel - Re: [PATCH v4 0/6] KVM: x86: Prep KVM hypercall handling for TDX

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Message-ID: <9fc1bc289254af9953e1a65ea7573facd0b54ac6.camel@intel.com>
Date: Thu, 28 Nov 2024 01:06:56 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "pbonzini@...hat.com" <pbonzini@...hat.com>, "seanjc@...gle.com"
	<seanjc@...gle.com>
CC: "thomas.lendacky@....com" <thomas.lendacky@....com>, "kvm@...r.kernel.org"
	<kvm@...r.kernel.org>, "Li, Xiaoyao" <xiaoyao.li@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"binbin.wu@...ux.intel.com" <binbin.wu@...ux.intel.com>, "Yamahata, Isaku"
	<isaku.yamahata@...el.com>
Subject: Re: [PATCH v4 0/6] KVM: x86: Prep KVM hypercall handling for TDX

On Wed, 2024-11-27 at 16:43 -0800, Sean Christopherson wrote:
> Effectively v4 of Binbin's series to handle hypercall exits to userspace in
> a generic manner, so that TDX
> 
> Binbin and Kai, this is fairly different that what we last discussed.  While
> sorting through Binbin's latest patch, I stumbled on what I think/hope is an
> approach that will make life easier for TDX.  Rather than have common code
> set the return value, _and_ have TDX implement a callback to do the same for
> user return MSRs, just use the callback for all paths.
> 
> As for abusing vcpu->run->hypercall.ret... It's obviously a bit gross, but
> I think it's a lesser evil than having multiple a one-line wrappers just to
> trampoline in the return code.

Doesn't seem to be "gross" to me, and AFAICT now for TDX we just need to play
with __kvm_emulate_hypercall() with a TDX-specific completion callback.

Which is nice.  Thanks!

For this series:

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