From: Sean Christopherson <seanjc@google.com>
To: Ignat Korchagin <ignat@cloudflare.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, stevensd@chromium.org,
kernel-team <kernel-team@cloudflare.com>
Subject: Re: Potential bug in TDP MMU
Date: Tue, 30 Nov 2021 20:23:34 +0000 [thread overview]
Message-ID: <YaaIRv0n2E8F5YpX@google.com> (raw)
In-Reply-To: <CALrw=nHTJpoSFFadmDL2EL95D2kAiH5G-dgLvU0L7X=emxrP2A@mail.gmail.com>
On Tue, Nov 30, 2021, Ignat Korchagin wrote:
> I have managed to reliably reproduce the issue on a QEMU VM (on a host
> with nested virtualisation enabled). Here are the steps:
>
> 1. Install gvisor as per
> https://gvisor.dev/docs/user_guide/install/#install-latest
> 2. Run
> $ for i in $(seq 1 100); do sudo runsc --platform=kvm --network=none
> do echo ok; done
>
> I've tried to recompile the kernel with the above patch, but
> unfortunately it does fix the issue. I'm happy to try other
> patches/fixes queued for 5.16-rc4
My best guest would be https://lore.kernel.org/all/20211120045046.3940942-5-seanjc@google.com/,
that bug results in KVM installing SPTEs into an invalid root. I think that could
lead to a use-after-free and/or double-free, which is usually what leads to the
"Bad page state" errors.
In the meantime, I'll try to repro.
> > > arch/x86/kvm/../../../virt/kvm/kvm_main.c:171
...
> > > After this the machine starts spitting some traces starting with:
> > >
> > > [177247.871683][T2343516] BUG: Bad page state in process <comm> pfn:fe680a
next prev parent reply other threads:[~2021-11-30 20:23 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-29 21:44 Potential bug in TDP MMU Ignat Korchagin
2021-11-30 9:29 ` Paolo Bonzini
2021-11-30 10:58 ` Ignat Korchagin
2021-11-30 10:59 ` Ignat Korchagin
2021-11-30 11:11 ` Paolo Bonzini
2021-11-30 11:19 ` Ignat Korchagin
2021-11-30 11:43 ` Ignat Korchagin
2021-11-30 11:49 ` Paolo Bonzini
2021-11-30 12:13 ` Paolo Bonzini
2021-11-30 20:23 ` Sean Christopherson [this message]
2021-12-01 23:44 ` Ignat Korchagin
2021-12-10 23:04 ` Ignat Korchagin
2021-12-11 1:34 ` David Matlack
2021-12-11 1:49 ` Paolo Bonzini
2021-12-11 17:46 ` David Matlack
2021-12-11 1:37 ` Paolo Bonzini
2021-12-11 2:39 ` Sean Christopherson
2021-12-11 9:38 ` Ignat Korchagin
2021-12-11 20:49 ` Paolo Bonzini
2021-12-13 16:14 ` Sean Christopherson
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