Re: [REGRESSION] 07ec51480b5e ("virtio_pci: use shared interrupts for virtqueues") causes crashes in guest

[Jason Wang]

This is a multi-part message in MIME format.

On 2017å03æ23æ 08:30, Laura Abbott wrote:
> Hi,
>
> Fedora has received multiple reports of crashes when running
> 4.11 as a guest
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1430297
> https://bugzilla.redhat.com/show_bug.cgi?id=1434462
> https://bugzilla.kernel.org/show_bug.cgi?id=194911
> https://bugzilla.redhat.com/show_bug.cgi?id=1433899
>
> The crashes are not always consistent but they are generally
> some flavor of oops or GPF in virtio related code. Multiple people
> have done bisections (Thank you Thorsten Leemhuis and
> Richard W.M. Jones) and found this commit to be at fault
>
> 07ec51480b5eb1233f8c1b0f5d7a7c8d1247c507 is the first bad commit
> commit 07ec51480b5eb1233f8c1b0f5d7a7c8d1247c507
> Author: Christoph Hellwig <hch@xxxxxx>
> Date:   Sun Feb 5 18:15:19 2017 +0100
>
>      virtio_pci: use shared interrupts for virtqueues
>      
>      This lets IRQ layer handle dispatching IRQs to separate handlers for the
>      case where we don't have per-VQ MSI-X vectors, and allows us to greatly
>      simplify the code based on the assumption that we always have interrupt
>      vector 0 (legacy INTx or config interrupt for MSI-X) available, and
>      any other interrupt is request/freed throught the VQ, even if the
>      actual interrupt line might be shared in some cases.
>      
>      This allows removing a great deal of variables keeping track of the
>      interrupt state in struct virtio_pci_device, as we can now simply walk the
>      list of VQs and deal with per-VQ interrupt handlers there, and only treat
>      vector 0 special.
>      
>      Additionally clean up the VQ allocation code to properly unwind on error
>      instead of having a single global cleanup label, which is error prone,
>      and in this case also leads to more code.
>      
>      Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>      Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
>
> :040000 040000 79a8267ffb73f9d244267c5f68365305bddd4696 8832a160b978710bbd24ba6966f462b3faa27fcc M	drivers
>
> It doesn't revert cleanly so we haven't been able to do a clean
> test. Any ideas?
>
> Thanks,
> Laura

Hello:

Can you try the attached patch to see if it solves the problem? (At 
least it silent KASan warnings for me).

Thanks