From: Maxim Levitsky <mlevitsk@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, Wanpeng Li <wanpengli@tencent.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>,
linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Jim Mattson <jmattson@google.com>,
x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] KVM: x86: fix a typo in __try_cmpxchg_user that caused cmpxchg to be not atomic
Date: Mon, 16 May 2022 16:14:31 +0300 [thread overview]
Message-ID: <f05dcf66ed2bfb7d113ce0d9a261569959265c68.camel@redhat.com> (raw)
In-Reply-To: <Yn17urxf7vprODed@google.com>
On Thu, 2022-05-12 at 21:27 +0000, Sean Christopherson wrote:
> On Thu, May 12, 2022, Paolo Bonzini wrote:
> > On 5/12/22 12:14, Maxim Levitsky wrote:
> > > Yes, this is the root cause of the TDP mmu leak I was doing debug of in the last week.
> > > Non working cmpxchg on which TDP mmu relies makes it install two differnt shadow pages
> > > under same spte.
> >
> > Awesome! And queued, thanks.
>
> If you haven't done so already, can you add
>
> Cc: stable@vger.kernel.org
When I posted my patch, I checked that the patch didn't reach mainline yet,
so I assumed that it won't be in -stable either yet, although it was CCed there.
>
> Also, given that we have concrete proof that not honoring atomic accesses can have
> dire consequences for the guest, what about adding a capability to turn the emul_write
> path into an emulation error?
>
This is a good idea. It might though break some guests - I did see that
warning few times, that is why I wasn't alert by the fact that it started showing up more often.
I'll take a look at this soon.
Best regards,
Maxim Levitsky
next prev parent reply other threads:[~2022-05-16 13:14 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-02 0:49 [PATCH v2 0/5] x86: uaccess CMPXCHG + KVM bug fixes Sean Christopherson
2022-02-02 0:49 ` [PATCH v2 1/5] Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug Sean Christopherson
2022-02-02 0:49 ` [PATCH v2 2/5] x86/uaccess: Implement macros for CMPXCHG on user addresses Sean Christopherson
2022-02-02 0:49 ` [PATCH v2 3/5] KVM: x86: Use __try_cmpxchg_user() to update guest PTE A/D bits Sean Christopherson
2022-02-02 0:49 ` [PATCH v2 4/5] KVM: x86: Use __try_cmpxchg_user() to emulate atomic accesses Sean Christopherson
2022-05-12 10:14 ` [PATCH] KVM: x86: fix a typo in __try_cmpxchg_user that caused cmpxchg to be not atomic Maxim Levitsky
2022-05-12 12:45 ` Vitaly Kuznetsov
2022-05-12 13:48 ` Sean Christopherson
2022-05-12 15:47 ` Paolo Bonzini
2022-05-12 21:27 ` Sean Christopherson
2022-05-16 13:14 ` Maxim Levitsky [this message]
2022-05-16 14:03 ` Sean Christopherson
2022-02-02 0:49 ` [PATCH v2 5/5] KVM: x86: Bail to userspace if emulation of atomic user access faults Sean Christopherson
2022-04-01 7:53 ` [PATCH v2 0/5] x86: uaccess CMPXCHG + KVM bug fixes Paolo Bonzini
2022-04-01 17:07 ` Tadeusz Struk
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