Re: [Xen-devel] [PATCH for-4.5] libxl: remove existence check for PCI device hotplug

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Nov 19, 2014 at 04:01:54PM -0500, Konrad Rzeszutek Wilk wrote:
> On Mon, Nov 17, 2014 at 12:10:34PM +0000, Wei Liu wrote:
> > The existence check is to make sure a device is not added to a guest
> > multiple times.
> > 
> > PCI device backend path has different rules from vif, disk etc. For
> > example:
> > /local/domain/0/backend/pci/9/0/dev-1/0000:03:10.1
> > /local/domain/0/backend/pci/9/0/key-1/0000:03:10.1
> > /local/domain/0/backend/pci/9/0/dev-2/0000:03:10.2
> > /local/domain/0/backend/pci/9/0/key-2/0000:03:10.2
> > 
> > The devid for PCI devices is hardcoded 0. libxl__device_exists only
> > checks up to /local/.../9/0 so it always returns true even the device is
> > assignable.
> > 
> > Remove invocation of libxl__device_exists. We're sure at this point that
> > the PCI device is assignable (hence no xenstore entry or JSON entry).
> > The check is done before hand. For HVM guest it's done by calling
> > xc_test_assign_device and for PV guest it's done by calling
> > pciback_dev_is_assigned.
> > 
> > Reported-by: Li, Liang Z <liang.z.li@xxxxxxxxx>
> > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> > Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> > Cc: Konrad Wilk <konrad.wilk@xxxxxxxxxx>
> > ---
> > This patch fixes a regression in 4.5.
> 
> Ouch! That needs then to be fixed.
> 
> Is the version you would want to commit? I did test it - and it

Yes.

> looked to do the right thing - thought the xen-pciback is stuck in the
> 7 state. However that is a seperate issue that I believe is due to
> Xen pciback not your patches.
> 

Thanks for testing.

Wei.

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