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Re: [Xen-devel] [PATCH] Dom0 PCI: fix SR-IOV function dependency link pr

To: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Dom0 PCI: fix SR-IOV function dependency link problem
From: Yu Zhao <yu.zhao@xxxxxxxxx>
Date: Thu, 04 Jun 2009 20:38:16 +0800
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "keir.fraser@xxxxxxxxxxxxx" <keir.fraser@xxxxxxxxxxxxx>
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Isaku Yamahata wrote:
On Wed, Jun 03, 2009 at 01:41:34PM +0800, Yu Zhao wrote:
PCIe Root Complex Integrated Endpoint does not implement ARI, so this
kind of endpoint uses 3-bit function number. The function dependency
link of the integrated endpoint should be calculated using the device
number field in conjunction with the value from function dependency
link register.

Normal SR-IOV endpoint always implements ARI and the function dependency
link register contains 8-bit function number (i.e. `devfn' from software
perspective).

Signed-off-by: Yu Zhao <yu.zhao@xxxxxxxxx>

# HG changeset patch
# User Yu Zhao <yu.zhao@xxxxxxxxx>
# Date 1244007161 -28800
# Node ID 3a959a6975152b741389d2eed1823d55be4f2889
# Parent  ec3442c2ed48eb11fcacd3fe31af48932f0a6645
PCI: fix SR-IOV function dependency link problem

PCIe Root Complex Integrated Endpoint does not implement ARI, so this
kind of endpoint uses 3-bit function number. The function dependency
link of the integrated endpoint should be calculated using the device
number field in conjunction with the value from function dependency
link register.

Normal SR-IOV endpoint always implements ARI and the function dependency
link register contains 8-bit function number (i.e. `devfn' from software
perspective).

Signed-off-by: Yu Zhao <yu.zhao@xxxxxxxxx>

diff -r ec3442c2ed48 -r 3a959a697515 drivers/pci/iov.c
--- a/drivers/pci/iov.c Wed Jun 03 13:30:08 2009 +0800
+++ b/drivers/pci/iov.c Wed Jun 03 13:32:41 2009 +0800
@@ -366,6 +366,8 @@
        iov->self = dev;
        pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
        pci_read_config_byte(dev, pos + PCI_SRIOV_FUNC_LINK, &iov->link);
+       if (!dev->bus->number)    /* Root Complex Integrated Endpoint */
+               iov->link = PCI_DEVFN(PCI_SLOT(dev->devfn), iov->link);
if (pdev)
                iov->dev = pci_dev_get(pdev);

Possibly the above check may work.
But pci capability list should be examined.
something like
  rpcap = pci_find_capability(pdev, PCI_CAP_ID_EXP);
  if (!rpcap)
          pci_read_config_word(pdev, rpcap + PCI_CAP_FLAGS, &cap);
          if (cap == PCI_EXP_TYPE_RC_END)

It will works well since the capability check is already done before doing anything else:

int pci_iov_init(struct pci_dev *dev)
{
        int pos;

        pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_SRIOV);
        if (pos)
                return sriov_init(dev, pos);

        return -ENODEV;
}

Thanks,
Yu

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