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From: Paolo Bonzini <pbonzini@redhat.com>
To: stsp <stsp2@yandex.ru>, Jim Mattson <jmattson@google.com>
Cc: Sean Christopherson <seanjc@google.com>,
	kvm@vger.kernel.org, David Woodhouse <dwmw@amazon.co.uk>,
	"ntsironis@arrikto.com" <ntsironis@arrikto.com>
Subject: Re: exception vs SIGALRM race (was: Re: guest/host mem out of sync on core2duo?)
Date: Wed, 7 Jul 2021 01:41:13 +0200	[thread overview]
Message-ID: <54270fb7-91ac-f10d-5879-956f42372536@redhat.com> (raw)
In-Reply-To: <eadbc511-3270-8a8e-a2d8-a8eb1fccb8c0@yandex.ru>

On 07/07/21 00:22, stsp wrote:
> I confirm that this works, thanks.
> Sadly the problematic patch was
> CCed to -stable, and is now present
> in all kernels, like ubuntu's 5.8.0-55-generic.
> Since AFAICT it didn't contain the
> important/security fix, I think it
> shouldn't have been CCed to -stable.
> 
> Can we revert it from -stable?
> That will mean a relatively quick
> fix for most of current users.

It was a bugfix, see the commit message:

     when userspace requests an IRQ window vmexit, an interrupt in the
     local APIC can cause kvm_cpu_has_interrupt() to be true and thus
     kvm_vcpu_ready_for_interrupt_injection() to return false.  When this
     happens, vcpu_run does not exit to userspace but the interrupt window
     vmexits keep occurring.  The VM loops without any hope of making progress.

Thanks for the testing!

Paolo


  reply	other threads:[~2021-07-06 23:41 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-12 22:49 guest/host mem out of sync on core2duo? stsp
2021-06-13 12:36 ` stsp
2021-06-14 17:06 ` Sean Christopherson
2021-06-14 17:32   ` stsp
2021-06-17 14:42     ` Sean Christopherson
2021-06-18 15:59       ` stsp
2021-06-18 21:07         ` Jim Mattson
2021-06-18 21:55           ` stsp
2021-06-18 22:06             ` Jim Mattson
2021-06-18 22:26               ` stsp
2021-06-18 22:32               ` Sean Christopherson
2021-06-19  0:11                 ` stsp
2021-06-19  0:54                   ` Sean Christopherson
2021-06-19  9:18                     ` stsp
2021-06-21  2:34           ` exception vs SIGALRM race (was: Re: guest/host mem out of sync on core2duo?) stsp
2021-06-21 22:33             ` Jim Mattson
2021-06-21 23:32               ` stsp
2021-06-22  0:27               ` stsp
2021-06-28 21:47                 ` Jim Mattson
2021-06-28 21:50                   ` stsp
2021-06-28 22:00                   ` stsp
2021-06-28 22:27                     ` Jim Mattson
2021-07-06 16:28                       ` Paolo Bonzini
2021-07-06 22:22                         ` stsp
2021-07-06 23:41                           ` Paolo Bonzini [this message]
2021-06-23 23:38               ` exception vs SIGALRM race (with test-case now!) stsp
2021-06-24  0:11                 ` stsp
2021-06-24  0:25                   ` stsp
2021-06-24 18:05                     ` exception vs SIGALRM race on core2 CPUs (with qemu-based test-case this time!) stsp
2021-06-24 18:07                     ` stsp
2021-06-25 23:35                       ` exception vs SIGALRM race on core2 CPUs (with fix!) stsp
2021-06-26  0:15                         ` Jim Mattson
2021-06-26  0:35                           ` stsp
2021-06-26 21:50                           ` stsp
2021-06-27 12:13                           ` stsp
2021-06-26 14:03               ` exception vs SIGALRM race (another patch) stsp

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