Re: [PATCH 1/5] iov: Update virtfn_max_buses to validate offset and stride

From: Alexander Duyck
Date: Wed Oct 28 2015 - 13:57:19 EST

On 10/28/2015 09:32 AM, Bjorn Helgaas wrote:
Hi Alex,

Thanks a lot for cleaning this up. I think this is a great
improvement over what I did.

On Tue, Oct 27, 2015 at 01:52:15PM -0700, Alexander Duyck wrote:
This patch pulls the validation of offset and stride into virtfn_max_buses.
The general idea is to validate offset and stride for each possible value
of numvfs in addition to still determining the maximum bus value for the

I also reversed the loop as the most likely maximum will be when numvfs is
set to total_VFs. In addition this makes it so that we loop down to a
value of 0 for numvfs which should be the resting state for the register.

Fixes: 8e20e89658f2 ("PCI: Set SR-IOV NumVFs to zero after enumeration")
Signed-off-by: Alexander Duyck <aduyck@xxxxxxxxxxxx>

I'd like to squash this together with my patch instead of having fixes
on top of fixes. What do you think of the following? (This applies
on top of 70675e0b6a1a ("PCI: Don't try to restore VF BARs")).

commit c20e11b572c5d4e4f01c86580a133122fbd13cfa
Author: Alexander Duyck <aduyck@xxxxxxxxxxxx>
Date: Wed Oct 28 10:54:32 2015 -0500

PCI: Set SR-IOV NumVFs to zero after enumeration

The enumeration path should leave NumVFs set to zero. But after
4449f079722c ("PCI: Calculate maximum number of buses required for VFs"),
we call virtfn_max_buses() in the enumeration path, which changes NumVFs.
This NumVFs change is visible via lspci and sysfs until a driver enables

Iterate from TotalVFs down to zero so NumVFs is zero when we're finished
computing the maximum number of buses. Validate offset and stride in
the loop, so we can test it at every possible NumVFs setting. Rename
virtfn_max_buses() to compute_max_vf_buses() to hint that it does have a
side effect of updating iov->max_VF_buses.

[bhelgaas: changelog, rename, reverse sense of error path]
Fixes: 4449f079722c ("PCI: Calculate maximum number of buses required for VFs")
Based-on-patch-by: Ethan Zhao <ethan.zhao@xxxxxxxxxx>
Signed-off-by: Alexander Duyck <aduyck@xxxxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

This looks fine to me.

Acked-by: Alexander Duyck <aduyck@xxxxxxxxxxxx>

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