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

Jan Kiszka
2011-06-06T22:04:16Z

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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.

>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>>
>> PS: What's the state of those KVM patches? Will they make it into 3.0?
>
> The PCI save/restore ones are in:
>
> f8fcfd775523347afe460dc3a0f45d0479e784a2
> ffbdd3f7931fb7cb7e36d00d16303ec433be5145
> 24a4742f0be6226eb0106fbb17caf4d711d1ad43

Oh, they are just missing in kvm.git so far.

Jan

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