Re: [Xen-devel] [PATCH 2/5] xen/pciback: Support pci_reset_function,aka FLR or D3 support.

[Don Dutile]

On 01/05/2012 04:34 PM, Konrad Rzeszutek Wilk wrote:
> On Thu, Jan 05, 2012 at 01:58:50PM -0500, Don Dutile wrote:
> > On 01/05/2012 05:24 AM, Ian Campbell wrote:
> > > On Thu, 2012-01-05 at 00:46 +0000, Konrad Rzeszutek Wilk wrote:
> > > > We use the __pci_reset_function_locked to perform the action.
> > > > Also on attaching ("bind") and detaching ("unbind") we save and
> > > > restore the configuration states. When the device is disconnected
> > > >from a guest we use the "pci_reset_function" to also reset the
> > > > device before being passed to another guest.
> > >
> > > Currently I thought the toolstack was supposed to do the reset (by
> > > writing to the reset node in sysfs) as it was (de)assigning devices
> > > to/from guests. That's not to say that there isn't an argument for
> > > preferring to do it kernels side but it would be interesting to make
> > > that argument explicitly.
> > >
> > > I guess the toolstack doesn't currently save/restore the configuration
> > > state, could it though? I guess the state is all available in sysfs. On
> > pci_reset_function() saves the config state before doing a fcn-level reset.
> >
> > the libvirt toolstack handles the unbind/reset/bind functionality
> > and is used by kvm for it's device assignment.
>
> The KVM assigned PCI module does the call as well via the ioctls when
> assigning/de-assigning the PCI device. Look in 'kvm_free_assigned_device'
> and in 'kvm_vm_ioctl_assign_device'.
>
> Is that what you mean by the unbind/reset/bind functionality - the ioctl
> call?
It's done in both places (libvirt & kvm-ioctl).

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