diff mbox

PCI/IOV: Skip initializing the base addresses from the VF config space

Message ID 1520051590-11750-1-git-send-email-karahmed@amazon.de (mailing list archive)
State New, archived
Headers show

Commit Message

KarimAllah Ahmed March 3, 2018, 4:33 a.m. UTC
Per PCIe r4.0, sec 9.3.4.1.11, the BARs registers from the VF config space
are all RO Zero for PCI VFs. So just skip reading them for VFs.

This is an optimization when enabling SR-IOV on a device with many VFs.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
 drivers/pci/probe.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Bjorn Helgaas March 19, 2018, 7:57 p.m. UTC | #1
On Sat, Mar 03, 2018 at 05:33:10AM +0100, KarimAllah Ahmed wrote:
> Per PCIe r4.0, sec 9.3.4.1.11, the BARs registers from the VF config space
> are all RO Zero for PCI VFs. So just skip reading them for VFs.
> 
> This is an optimization when enabling SR-IOV on a device with many VFs.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: linux-pci@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>

Applied to pci/virtualization for v4.17, thanks!

> ---
>  drivers/pci/probe.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index a96837e..7204d46 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -329,6 +329,10 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
>  	if (dev->non_compliant_bars)
>  		return;
>  
> +	/* Per PCIe r4.0, sec 9.3.4.1.11, the VF BARs are all RO Zero */
> +	if (dev->is_virtfn)
> +		return;
> +
>  	for (pos = 0; pos < howmany; pos++) {
>  		struct resource *res = &dev->resource[pos];
>  		reg = PCI_BASE_ADDRESS_0 + (pos << 2);
> -- 
> 2.7.4
>
diff mbox

Patch

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index a96837e..7204d46 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -329,6 +329,10 @@  static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
 	if (dev->non_compliant_bars)
 		return;
 
+	/* Per PCIe r4.0, sec 9.3.4.1.11, the VF BARs are all RO Zero */
+	if (dev->is_virtfn)
+		return;
+
 	for (pos = 0; pos < howmany; pos++) {
 		struct resource *res = &dev->resource[pos];
 		reg = PCI_BASE_ADDRESS_0 + (pos << 2);