Re: [PATCH v4 2/7] PCI: Ignore BAR updates on virtual functions

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

On Mon, Nov 28, 2016 at 10:14:29PM -0600, Bjorn Helgaas wrote:
>VF BARs are read-only zero, so updating VF BARs will not have any effect.
>See the SR-IOV spec r1.1, sec 3.4.1.11.
>
>We already ignore these updates because of 70675e0b6a1a ("PCI: Don't try to
>restore VF BARs"); this merely restructures it slightly to make it easier
>to split updates for standard and SR-IOV BARs.
>
>Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>CC: Wei Yang <richard.weiyang@gmail.com>

Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>

>---
> drivers/pci/pci.c       |    4 ----
> drivers/pci/setup-res.c |    5 ++---
> 2 files changed, 2 insertions(+), 7 deletions(-)
>
>diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>index ba34907..631eac2 100644
>--- a/drivers/pci/pci.c
>+++ b/drivers/pci/pci.c
>@@ -564,10 +564,6 @@ static void pci_restore_bars(struct pci_dev *dev)
> {
> 	int i;
>
>-	/* Per SR-IOV spec 3.4.1.11, VF BARs are RO zero */
>-	if (dev->is_virtfn)
>-		return;
>-
> 	for (i = 0; i < PCI_BRIDGE_RESOURCES; i++)
> 		pci_update_resource(dev, i);
> }
>diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
>index 66c4d8f..d2a32d8 100644
>--- a/drivers/pci/setup-res.c
>+++ b/drivers/pci/setup-res.c
>@@ -36,10 +36,9 @@ void pci_update_resource(struct pci_dev *dev, int resno)
> 	enum pci_bar_type type;
> 	struct resource *res = dev->resource + resno;
>
>-	if (dev->is_virtfn) {
>-		dev_warn(&dev->dev, "can't update VF BAR%d\n", resno);
>+	/* Per SR-IOV spec 3.4.1.11, VF BARs are RO zero */
>+	if (dev->is_virtfn)
> 		return;
>-	}
>
> 	/*
> 	 * Ignore resources for unimplemented BARs and unused resource slots
>