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Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels |
Date: |
Mon, 16 Apr 2012 12:25:37 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2012-04-15 11:44, Avi Kivity wrote:
> The trigger is probably
>
>> commit f1c1da2bde712812a3e0f9a7a7ebe7a916a4b5f4
>> Author: Jan Kiszka <address@hidden>
>> Date: Tue Oct 18 18:23:11 2011 +0200
>>
>> KVM: SVM: Keep intercepting task switching with NPT enabled
>>
>> AMD processors apparently have a bug in the hardware task switching
>> support when NPT is enabled. If the task switch triggers a NPF, we can
>> get wrong EXITINTINFO along with that fault. On resume, spurious
>> exceptions may then be injected into the guest.
>>
>> We were able to reproduce this bug when our guest triggered #SS
>> and the
>> handler were supposed to run over a separate task with not yet touched
>> stack pages.
>>
>> Work around the issue by continuing to emulate task switches even in
>> NPT mode.
>>
>> Signed-off-by: Jan Kiszka <address@hidden>
>> Signed-off-by: Marcelo Tosatti <address@hidden>
>
> Although it's not the patch's direct fault - it simply exposed an
> existing bug in kvm.
>
> Things to try:
> - revert the patch with a newer kernel
> - try 3.4-rc2 which has some task switch fixes from Kevin; if you want a
> Fedora kernel, use rawhide's [2]
> - post traces [1]
>
> Jan, Joerg, was an AMD erratum published for the bug?
It wasn't an erratum but a documented feature limitation in the AMD
architecture that was simply ignored by the old code.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Gerhard Wiesinger, 2012/04/12
- Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Avi Kivity, 2012/04/15
- Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Gerhard Wiesinger, 2012/04/15
- Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels,
Jan Kiszka <=
- Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Avi Kivity, 2012/04/16
- Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Roedel, Joerg, 2012/04/16
- Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Avi Kivity, 2012/04/16
- Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Gerhard Wiesinger, 2012/04/16
- Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Avi Kivity, 2012/04/16
Re: [Qemu-devel] DOS VM problem with QEMU-KVM and newer kernels, Gerhard Wiesinger, 2012/04/17