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Message-ID: <9d414a3cadb3e0c6845bebdd805a91a76e56b4d0.camel@infradead.org>
Subject: Re: [PATCH 3/3] KVM: Explicitly disallow activatating a
 gfn_to_pfn_cache with INVALID_GPA
From: David Woodhouse <dwmw2@infradead.org>
To: Sean Christopherson <seanjc@google.com>, Paolo Bonzini
 <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, 
	syzbot+106a4f72b0474e1d1b33@syzkaller.appspotmail.com, Paul Durrant
	 <paul@xen.org>
Date: Wed, 20 Mar 2024 08:20:48 +0000
In-Reply-To: <20240320001542.3203871-4-seanjc@google.com>
References: <20240320001542.3203871-1-seanjc@google.com>
	 <20240320001542.3203871-4-seanjc@google.com>
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On Tue, 2024-03-19 at 17:15 -0700, Sean Christopherson wrote:
> Explicit disallow activating a gfn_to_pfn_cache with an error gpa, i.e.
> INVALID_GPA, to ensure that KVM doesn't mistake a GPA-based cache for an
> HVA-based cache (KVM uses INVALID_GPA as a magic value to differentiate
> between GPA-based and HVA-based caches).
>=20
> WARN if KVM attempts to activate a cache with INVALID_GPA, purely so that
> new caches need to at least consider what to do with a "bad" GPA, as all
> existing usage of kvm_gpc_activate() guarantees gpa !=3D INVALID_GPA.=C2=
=A0 I.e.
> removing the WARN in the future is completely reasonable if doing so woul=
d
> yield cleaner/better code overall.
>=20
> Signed-off-by: Sean Christopherson <seanjc@google.com>


Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>


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