From: Sean Christopherson <seanjc@google.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+760a73552f47a8cd0fd9@syzkaller.appspotmail.com,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Hou Wenlong <houwenlong.hwl@antgroup.com>
Subject: Re: [PATCH 1/3] KVM: x86: Mark TSS busy during LTR emulation _after_ all fault checks
Date: Tue, 12 Jul 2022 17:29:51 +0000 [thread overview]
Message-ID: <Ys2vj6snMhuSJbso@google.com> (raw)
In-Reply-To: <8307c007823eac899d3a017d1616e0d08a653185.camel@redhat.com>
On Tue, Jul 12, 2022, Maxim Levitsky wrote:
> On Mon, 2022-07-11 at 23:27 +0000, Sean Christopherson wrote:
> > Wait to mark the TSS as busy during LTR emulation until after all fault
> > checks for the LTR have passed. Specifically, don't mark the TSS busy if
> > the new TSS base is non-canonical.
>
>
> Took me a while to notice it but I see the canonical check now, so the patch
> makes sense, and so:
>
> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
>
> Unrelated, but I do wonder why we use cmpxchg_emulated for setting the busy
> bit, while we use write_segment_descriptor to set the accessed bit.
99% certain it's a historical KVM bug in how it updates the accessed bit.
next prev parent reply other threads:[~2022-07-12 17:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-11 23:27 [PATCH 0/3] KVM: x86: Fix fault-related bugs in LTR/LLDT emulation Sean Christopherson
2022-07-11 23:27 ` [PATCH 1/3] KVM: x86: Mark TSS busy during LTR emulation _after_ all fault checks Sean Christopherson
2022-07-12 13:35 ` Maxim Levitsky
2022-07-12 17:29 ` Sean Christopherson [this message]
2022-07-11 23:27 ` [PATCH 2/3] KVM: x86: Set error code to segment selector on LLDT/LTR non-canonical #GP Sean Christopherson
2022-07-12 13:37 ` Maxim Levitsky
2022-07-12 17:31 ` Sean Christopherson
2022-07-11 23:27 ` [PATCH 3/3] KVM: x86: WARN only once if KVM leaves a dangling userspace I/O request Sean Christopherson
2022-07-12 13:34 ` Maxim Levitsky
2022-07-12 1:07 ` [PATCH 0/3] KVM: x86: Fix fault-related bugs in LTR/LLDT emulation Nadav Amit
2022-07-14 18:20 ` Sean Christopherson
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