Re: [Xen-devel] [PATCH 1/2] libxl: Wait until QEMU removed the device before tearing it down

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Boris Ostrovsky writes ("Re: [PATCH 1/2] libxl: Wait until QEMU removed the 
device before tearing it down"):
> But it doesn't help with the second part (the one that shows Linux 
> WARNING), because we still may try to reset the device before guest 
> kernel is done unloading the driver. Reproducing that problem is 
> probably dependent on the guest/driver: in this particular case the igb 
> driver does an IN instruction while unloading the driver and if that 
> instruction fails (which may happen if the device is gone from the POV 
> of toolstack) then it triggers the warning.

Right.  OK.  Looking at the code, I think you have convinced about
that.    I will review the implementation in your patch now.

> And I believe we still need part of the second patch --- the one that 
> removes call to xc_domain_irq_permission() for PV guests (after your 
> patch is applied): this call will fail because xc_physdev_unmap_pirq() 
> above it will cause hypervisor to do unmap_domain_pirq()->irq_deny_access()

What call to xc_physdev_unmap_pirq ?  I see one in the PV path.

Ian.

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