linux-kernel - Re: [PATCH] KVM: x86/mmu: Only zap valid non-mirror roots in kvm_zap_gfn

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <Z33hJ8mcnu6xKnvL@yzhao56-desk.sh.intel.com>
Date: Wed, 8 Jan 2025 10:21:27 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: Paolo Bonzini <pbonzini@...hat.com>
CC: Sean Christopherson <seanjc@...gle.com>, <rick.p.edgecombe@...el.com>,
	<binbin.wu@...ux.intel.com>, <linux-kernel@...r.kernel.org>,
	<kvm@...r.kernel.org>
Subject: Re: [PATCH] KVM: x86/mmu: Only zap valid non-mirror roots in
 kvm_zap_gfn_range()

On Tue, Jan 07, 2025 at 03:01:05PM +0100, Paolo Bonzini wrote:
> On Tue, Jan 7, 2025 at 12:49 AM Sean Christopherson <seanjc@...gle.com> wrote:
> > On Mon, Dec 23, 2024, Yan Zhao wrote:
> > > On Sun, Dec 22, 2024 at 08:28:56PM +0100, Paolo Bonzini wrote:
> > > > I think we should treat honoring of guest PAT like zap-memslot-only,
> > > > and make it a quirk that TDX disables.  Making it a quirk adds a bit of
> > > > complexity, but it documents why the code exists and it makes it easy for
> > > > TDX to disable it.
> >
> > Belated +1.  Adding a quirk for honoring guest PAT was on my todo list.  A quirk
> > also allows setups that don't provide a Bochs device to honor guest PAT, which
> > IIRC is needed for virtio-gpu with a non-snooping graphics device.
> >
> > > Thanks! Will do in this way after the new year.
> >
> > Nice!  One oddity to keep in mind when documenting the quirk is that KVM always
> > honors guest PAT when running on AMD.  :-/
> 
> And also when implementing it - the quirk should be absent on AMD.
Got it!