linux-kernel - Re: [PATCH 1/7] KVM: x86: Free vCPUs before freeing VM state

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: <CABgObfZWqBm089dkOpWwX-d6Bgp84zP_0Gow4ow7ZKHov=8oxg@mail.gmail.com>
Date: Wed, 26 Feb 2025 10:18:26 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Madhavan Srinivasan <maddy@...ux.ibm.com>, 
	Anup Patel <anup@...infault.org>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Christian Borntraeger <borntraeger@...ux.ibm.com>, Janosch Frank <frankja@...ux.ibm.com>, 
	Claudio Imbrenda <imbrenda@...ux.ibm.com>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, kvm@...r.kernel.org, loongarch@...ts.linux.dev, 
	linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, 
	kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, Aaron Lewis <aaronlewis@...gle.com>, 
	Jim Mattson <jmattson@...gle.com>, Yan Zhao <yan.y.zhao@...el.com>, 
	Rick P Edgecombe <rick.p.edgecombe@...el.com>, Kai Huang <kai.huang@...el.com>, 
	Isaku Yamahata <isaku.yamahata@...el.com>
Subject: Re: [PATCH 1/7] KVM: x86: Free vCPUs before freeing VM state

On Wed, Feb 26, 2025 at 1:27 AM Sean Christopherson <seanjc@...gle.com> wrote:
>
> On Wed, Feb 26, 2025, Paolo Bonzini wrote:
> > On 2/25/25 00:55, Sean Christopherson wrote:
> > > Free vCPUs before freeing any VM state, as both SVM and VMX may access
> > > VM state when "freeing" a vCPU that is currently "in" L2, i.e. that needs
> > > to be kicked out of nested guest mode.
> > >
> > > Commit 6fcee03df6a1 ("KVM: x86: avoid loading a vCPU after .vm_destroy was
> > > called") partially fixed the issue, but for unknown reasons only moved the
> > > MMU unloading before VM destruction.  Complete the change, and free all
> > > vCPU state prior to destroying VM state, as nVMX accesses even more state
> > > than nSVM.
> >
> > I applied this to kvm-coco-queue, I will place it in kvm/master too unless
> > you shout.
>
> Depends on what "this" is :-)
>
> My plan/hope is to land patches 1 and 2 in 6.14, i.e. in kvm/master

I meant only 1, but if you want to have 2 as well then that's fine too.

As to kvm-coco-queue, based on Yan's reply I have 1 (of course), 4 and
an extra patch to move kvm_x86_call(vm_destroy) at the very end of
kvm_arch_destroy_vm; I'll post everything as soon as I finish building
and testing.

Paolo

> rest are firmly 6.15 IMO.  And based on Yan's feedback, I'm planning on adding a
> few more cleanups (though I think they're fully additive, i.e. can go on top).
>