From: stsp <stsp2@yandex.ru>
To: Jim Mattson <jmattson@google.com>
Cc: Sean Christopherson <seanjc@google.com>, kvm@vger.kernel.org
Subject: exception vs SIGALRM race on core2 CPUs (with qemu-based test-case this time!)
Date: Thu, 24 Jun 2021 21:05:02 +0300 [thread overview]
Message-ID: <064bbd96-1a17-8929-6961-4f41f44fe884@yandex.ru> (raw)
In-Reply-To: <60ae8b9f-89af-e8b3-13c4-99ddea1ced90@yandex.ru>
24.06.2021 03:25, stsp пишет:
> What does this test-case do?
> It provokes the PF by writing to
> the NULL pointer. The PF handler
> checks if PF is coming from the
> right place, or from the nearby
> IRQ8 timer handler. If PF is coming
> from the very first instruction of
> the timer handler, then we got
> that nasty SIGALRM race and
> KVM exited to user-space with
> the pending PF exception.
>
> How to replicate the buggy setup?
Since I don't think anyone wanted
to install dosemu2, I now created
the qemu-based reproducer.
Unfortunately, even with qemu
you still need the real core2 CPU
to reproduce.
At least I don't know how to enable
the emulated VTx under qemu, but
maybe someone else knows.
So you need a disk image that I
uploaded here:
https://www.filemail.com/d/fvkwgqgcmrhsxmk
<https://www.filemail.com/d/fvkwgqgcmrhsxmk>
And you can run it like so:
|qemu-system-x86_64 -hda disk.img -enable-kvm \ -cpu host -bios
/usr/share/OVMF/OVMF_CODE.fd \ -device intel-hda -device hda-duplex -m
2G The result on a core2 CPU will be like here:
https://github.com/dosemu2/dosemu2/issues/1500#issuecomment-867838848
"Race DETECTED" means that the test-case detected the page-fault coming
from an interrupt handler, when it shouldn't. |
next prev parent reply other threads:[~2021-06-24 18:05 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
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 ` stsp [this message]
2021-06-24 18:07 ` exception vs SIGALRM race on core2 CPUs (with qemu-based test-case this time!) 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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