Re: [PATCH] pci-assign: Do not reset the device unless the kernel supports it

Jan Kiszka
2011-06-07T08:14:27Z

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On 2011-06-07 10:06, Avi Kivity wrote:
> On 06/07/2011 01:04 AM, Jan Kiszka wrote:
>> On 2011-06-06 23:48, Alex Williamson wrote:
>> > On Mon, 2011-06-06 at 23:30 +0200, Jan Kiszka wrote:
>> >> From: Jan Kiszka<jan.kiszka@siemens.com>
>> >>
>> >> At least kernels 2.6.38 and 2.6.39 do not properly support issuing a
>> >> reset on an assigned device and corrupt its config space. Prevent
>> >> this by checking for a host kernel with the required support,
>> tagged by
>> >> the to-be-introduced KVM_CAP_DEVICE_RESET.
>> >
>> > Wouldn't it be easier just to revert ed78661f in 2.6.39 stable? I
>> guess
>> > we don't have an option to do that for .38 since stable is done there,
>> > but there are also some intel-iommu breakages that won't make
>> stable for
>> > that release. It seems like the userspace invoked reset resolves
>> known,
>> > demonstrable issues of devices continuing to DMA into guest memory
>> while
>> > ed78661f is mostly a theoretical change.
>>
>> Easier would be this patch. But I don't mind reverting the problematic
>> commit in 39, whatever is preferred. We should just resolve the issue
>> finally.
>
> Kernel problems should be solved in the kernel (with exceptions of
> course, but don't see the need here).

Then please file a revert for stable ASAP.

Jan

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