linux-kernel - Re: [PATCH 19/21] KVM: TDX: Add an ioctl to create initial guest memory

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Message-ID: <32695ba6af19f46fed3307bd363c96b35001e0ae.camel@intel.com>
Date: Wed, 11 Sep 2024 00:11:23 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "pbonzini@...hat.com" <pbonzini@...hat.com>, "Zhao, Yan Y"
	<yan.y.zhao@...el.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "dmatlack@...gle.com"
	<dmatlack@...gle.com>, "nik.borisov@...e.com" <nik.borisov@...e.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>, "Huang, Kai" <kai.huang@...el.com>,
	"isaku.yamahata@...il.com" <isaku.yamahata@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 19/21] KVM: TDX: Add an ioctl to create initial guest
 memory

On Tue, 2024-09-10 at 12:13 +0200, Paolo Bonzini wrote:
> > Yan, do you think it is sufficient?
> 
> If you're actually requiring that the other locks are sufficient, then 
> there can be no ENOENT.
> 
> Maybe:
> 
>         /*
>          * The private mem cannot be zapped after kvm_tdp_map_page()
>          * because all paths are covered by slots_lock and the
>          * filemap invalidate lock.  Check that they are indeed enough.
>          */
>         if (IS_ENABLED(CONFIG_KVM_PROVE_MMU)) {
>                 scoped_guard(read_lock, &kvm->mmu_lock) {
>                         if (KVM_BUG_ON(kvm,
>                                 !kvm_tdp_mmu_gpa_is_mapped(vcpu, gpa)) {
>                                 ret = -EIO;
>                                 goto out;
>                         }
>                 }
>         }

True. We can put it behind CONFIG_KVM_PROVE_MMU.