Re: [PATCH v2] iov: restore NumVFs register to 0 before return from virtfn_max_buses()

[ethan zhao <ethan.zhao@xxxxxxxxxx>]

Bjorn,

On 2015/10/22 4:54, Bjorn Helgaas wrote:
> On Thu, Oct 15, 2015 at 12:16:00PM -0500, Bjorn Helgaas wrote:
> > Hi Ethan,
> >
> > On Wed, Sep 16, 2015 at 12:19:53PM +0900, Ethan Zhao wrote:
> > > After commit 4449f079722c ("PCI: Calculate maximum number of buses
> > > required for VFs"),the initial value of NumVFs register was left 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 restore the NumVFs register to zero after the
> > > calculation of max_VF_buses was done and before return from
> > > virtfn_max_buses().
> > >
> > > Tested on stable 4.1 and passed building on stable 4.3-rc1
> > >
> > > Signed-off-by: Ethan Zhao <ethan.zhao@xxxxxxxxxx>
> > > Tested-by: Sriharsha Yadagudde <sriharsha.devdas@xxxxxxxxxx>
> > Can you test the patch below?  I'm trying to avoid touching
> > PCI_SRIOV_NUM_VF in more than one place, and I think it's OK to set it
> > and test offset/stride at the end, instead of setting NUM_VF to zero,
> > testing offset/stride, computing max_bus, then setting NUM_VF to zero
> > again.
> I applied the patch below to pci/virtualization for v4.4.

 Sorry, seems I missed your above mail, will apply your patch to my 
local branch and ask QA test again.

 Thanks,
 Ethan
> > commit 8e20e89658f23b8d16b1e21810e9f63c8625129c
> > Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > Date:   Thu Oct 15 11:31:21 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
> >      SR-IOV.
> >      
> >      Set NumVFs to zero after virtfn_max_buses() computes the maximum number of
> >      buses.
> >      
> >      Fixes: 4449f079722c ("PCI: Calculate maximum number of buses required for VFs")
> >      Based-on-patch-by: Ethan Zhao <ethan.zhao@xxxxxxxxxx>
> >      Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> >
> > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> > index ee0ebff..0202ab0 100644
> > --- a/drivers/pci/iov.c
> > +++ b/drivers/pci/iov.c
> > @@ -384,7 +384,7 @@ static int sriov_init(struct pci_dev *dev, int pos)
> >   	int rc;
> >   	int nres;
> >   	u32 pgsz;
> > -	u16 ctrl, total, offset, stride;
> > +	u16 ctrl, total;
> >   	struct pci_sriov *iov;
> >   	struct resource *res;
> >   	struct pci_dev *pdev;
> > @@ -414,11 +414,6 @@ static int sriov_init(struct pci_dev *dev, int pos)
> >   
> >   found:
> >   	pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
> > -	pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0);
> > -	pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
> > -	pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);
> > -	if (!offset || (total > 1 && !stride))
> > -		return -EIO;
> >   
> >   	pci_read_config_dword(dev, pos + PCI_SRIOV_SUP_PGSIZE, &pgsz);
> >   	i = PAGE_SHIFT > 12 ? PAGE_SHIFT - 12 : 0;
> > @@ -456,8 +451,6 @@ found:
> >   	iov->nres = nres;
> >   	iov->ctrl = ctrl;
> >   	iov->total_VFs = total;
> > -	iov->offset = offset;
> > -	iov->stride = stride;
> >   	iov->pgsz = pgsz;
> >   	iov->self = dev;
> >   	pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
> > @@ -475,6 +468,11 @@ found:
> >   	dev->sriov = iov;
> >   	dev->is_physfn = 1;
> >   	iov->max_VF_buses = virtfn_max_buses(dev);
> > +	pci_iov_set_numvfs(dev, 0);
> > +	if (!iov->offset || (total > 1 && !iov->stride)) {
> > +		rc = -EIO;
> > +		goto failed;
> > +	}
> >   
> >   	return 0;
> >   
> > @@ -484,6 +482,7 @@ failed:
> >   		res->flags = 0;
> >   	}
> >   
> > +	dev->sriov = NULL;
> >   	kfree(iov);
> >   	return rc;
> >   }
> > --
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