Re: [PATCH] PCI: Support SRIOV on Legacy EndPoint device

From: Bjorn Helgaas
Date: Mon Feb 29 2016 - 13:00:25 EST

On Tue, Feb 09, 2016 at 01:08:58PM -0500, kelly.zytaruk@xxxxxxx wrote:
> From: Kelly Zytaruk <kelly.zytaruk@xxxxxxx>
> It is not neccessary to check for PCI_EXP_TYPE in sriov_init(). There appears to be no reason for the check.
> Some AMD GPUs have hardware support for grapics SRIOV.
> If the GPU has a display output then the GPU needs to support Legacy VGA operation.
> If CLASS_CODE = VGA then the device should have a Port Type = Legacy EndPoint.
> Therefore in order to enable SRIOV on a GPU with a display output, LEGACY_END_POINT is supported as a valid Port Type by removing the check for Port Type.
> Patch is also logged in Bugzilla #112221
> Signed-off-by: Kelly Zytaruk <kelly.zytaruk@xxxxxxx>

Applied to pci/virtualization for v4.6, with changelog as follows:

PCI: Support SR-IOV on any function type

Previously, we only supported SR-IOV on PCI Express Endpoints and Root
Complex Integrated Endpoints. This restriction has been present since
d1b054da8f59 ("PCI: initialize and release SR-IOV capability") added SR-IOV
support, but the spec does not require it. In fact, the SR-IOV spec r1.1,
sec 3.3, says the SR-IOV extended capability may be present for any Type 0

Remove the function type test, so we can support SR-IOV on any function.

Some AMD GPUs have display outputs, use the VGA class code, are Legacy
Endpoints, and support SR-IOV. This change allows Linux to enable SR-IOV
on these devices.

[bhelgaas: changelog]
Signed-off-by: Kelly Zytaruk <kelly.zytaruk@xxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

> ---
> drivers/pci/iov.c | 4 ----
> 1 file changed, 4 deletions(-)
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index 31f31d4..fe4bd0a 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -387,10 +387,6 @@ static int sriov_init(struct pci_dev *dev, int pos)
> struct resource *res;
> struct pci_dev *pdev;
> - if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END &&
> - pci_pcie_type(dev) != PCI_EXP_TYPE_ENDPOINT)
> - return -ENODEV;
> -
> pci_read_config_word(dev, pos + PCI_SRIOV_CTRL, &ctrl);
> if (ctrl & PCI_SRIOV_CTRL_VFE) {
> pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, 0);
> --
> --
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