Subject: Re: [PATCH V11 07/17] powerpc/pci: Don't unset pci resources for VFs

From: Benjamin Herrenschmidt <[email-masked]>
Date: Tue, 10 Feb 2015 13:14:11 +1100

On Tue, 2015-02-10 at 09:51 +0800, Wei Yang wrote:
> On Tue, Feb 10, 2015 at 11:36:24AM +1100, Benjamin Herrenschmidt wrote:
> >On Thu, 2015-01-15 at 10:27 +0800, Wei Yang wrote:
> >> If we're going to reassign resources with flag PCI_REASSIGN_ALL_RSRC, all
> >> resources will be cleaned out during device header fixup time and then get
> >> reassigned by PCI core. However, the VF resources won't be reassigned and
> >> thus, we shouldn't clean them out.
> >> 
> >> This patch adds a condition. If the pci_dev is a VF, skip the resource
> >> unset process.
> >
> >I don't understand this, can you elaborate ? Why wouldn't we reassign
> >the IOV resource just like everything else ?
> 
> Sure.
> 
> VFs work a little bit different from normal devices. On powernv platform, we
> have PCI_REASSIGN_ALL_RSRC set, which means all resource retrieved from
> hardware will be cleaned and re-assigned by kernel. While VF's resources are
> calculated from PF's IOV BAR, in virtfn_add(). And after this, there is not
> re-assign process for VFs.

I still don't undertand, you mean SR-IOV is assigned before we assign
everybody else ? That doesn't make sense to me...

Ben.

> >
> >Ben.
> >
> >> Signed-off-by: Wei Yang <[email-masked]>
> >> ---
> >>  arch/powerpc/kernel/pci-common.c |    4 ++++
> >>  1 file changed, 4 insertions(+)
> >> 
> >> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> >> index 37d512d..889f743 100644
> >> --- a/arch/powerpc/kernel/pci-common.c
> >> +++ b/arch/powerpc/kernel/pci-common.c
> >> @@ -788,6 +788,10 @@ static void pcibios_fixup_resources(struct pci_dev *dev)
> >>  		       pci_name(dev));
> >>  		return;
> >>  	}
> >> +
> >> +	if (dev->is_virtfn)
> >> +		return;
> >> +
> >>  	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
> >>  		struct resource *res = dev->resource + i;
> >>  		struct pci_bus_region reg;
> >
>