linux-kernel - Re: [PATCH 08/16] KVM: x86/mmu: Bug the VM if kvm_zap_gfn

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Message-ID: <bea44699-f0c0-4904-bbed-a987b1b97cf0@intel.com>
Date: Thu, 16 May 2024 11:14:54 +1200
From: "Huang, Kai" <kai.huang@...el.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>, "kvm@...r.kernel.org"
	<kvm@...r.kernel.org>, "pbonzini@...hat.com" <pbonzini@...hat.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>
CC: "Zhao, Yan Y" <yan.y.zhao@...el.com>, "sagis@...gle.com"
	<sagis@...gle.com>, "dmatlack@...gle.com" <dmatlack@...gle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"isaku.yamahata@...il.com" <isaku.yamahata@...il.com>, "Aktas, Erdem"
	<erdemaktas@...gle.com>
Subject: Re: [PATCH 08/16] KVM: x86/mmu: Bug the VM if kvm_zap_gfn_range() is
 called for TDX



On 16/05/2024 3:22 am, Edgecombe, Rick P wrote:
> On Wed, 2024-05-15 at 13:27 +0000, Huang, Kai wrote:
>>
>> kvm_zap_gfn_range() looks a generic function.  I think it makes more sense
>> to let the callers to explicitly check whether VM is TDX guest and do the
>> KVM_BUG_ON()?
> 
> Other TDX changes will prevent this function getting called. So basically like
> you are suggesting. This change is to catch any new cases that pop up, which we
> can't do at the caller.

But I think we need to see whether calling kvm_zap_gfn_range() is legal 
or not for TDX guest case by case, but not having a universal rule that 
this cannot be called for TDX guest, right?