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SubjectRe: [PATCH] iov: initialize NumVFs register to 0 at the end of sriov_init()
On Fri, Aug 21, 2015 at 06:51:25PM +0900, Ethan Zhao wrote:
> After commit 4449f079722c ("PCI: Calculate maximum number of buses
> required for VFs"),the initial value of NumVFs register was set to
> non-zero after sriov_init() and no VFs was enabled in device driver.
> this changed the behaviour of kernel exported by lspci and sysfs etc.
> so this patch initialize the NumVFs register to zero after the
> calculation of max_VF_buses was done.
>
> Tested on stable 4.1 and passed building on stable 4.2-rc7
>
> Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
> Tested-by: Sriharsha Yadagudde <sriharsha.devdas@oracle.com>
> ---
> drivers/pci/iov.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index ee0ebff..6969084 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -476,6 +476,7 @@ found:
> dev->is_physfn = 1;
> iov->max_VF_buses = virtfn_max_buses(dev);
>
> + pci_iov_set_numvfs(dev, 0);

I think it would be better to put this in virtfn_max_buses(), where we
clobbered numVFs in the first place. I'd also read the original value and
restore it, e.g.,

pci_read_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, &numvfs);
for (nr_virtfn = 1; nr_virtfn <= iov->total_VFs; nr_virtfn++) {
...
}
pci_iov_set_numvfs(dev, numvfs);
return max;

I know sriov_init() sets numVFs to zero before it calls virtfn_max_buses(),
but why rely on that extra knowledge?

> return 0;
>
> failed:
> --
> 1.8.3.1
>


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