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Date: Thu, 24 Sep 2015 14:50:19 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Alex Williamson <alex.williamson@...hat.com>
Cc: linux-pci@...r.kernel.org, mark.d.rustad@...el.com,
myron.stowe@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: Relax function 0 VPD test and relocate
On Tue, Sep 15, 2015 at 10:24:46PM -0600, Alex Williamson wrote:
> When we quirk a device with PCI_DEV_FLAGS_VPD_REF_F0 we're expecting
> to find a device where all the functions are identical. If we don't
> find that, we don't make VPD accessible through pci_vpd_ops. That
> means that if we quirk devices we shouldn't, we filter them out by
> hiding VPD entirely rather than allowing default access. Instead, we
> can flip this around to only quirk devices that match a slightly more
> rigorous test in the quirk, allowing regular access for anything else.
>
> Tests for the multifunction flag are removed since a) function 0 and
> the function under test are clearly a multifunction device if we're
> scanning a non-zero function in the same slot and b) at this point the
> flag is only set in the device under test if the multifunction bit is
> set in the PCI HEADER, which is a point of interpretation for the PCI
> spec.
>
> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
> ---
>
> This is potentially another stable candiate since we're continuing to
> iterate on 932c435caba8, but since we don't actually know of a device
> where VPD is blocked (we don't think my Skylake example actually
> supports VPD), I'm not including it. I would support it if requested
> though.
Applied with acks from Myron & Mark to for-linus for v4.3 with the
changelog below. I added a stable tag on the theory that there's not
really any benefit in having different flavors of this brand-new code.
PCI: Use function 0 VPD for identical functions, regular VPD for others
932c435caba8 ("PCI: Add dev_flags bit to access VPD through function 0")
added PCI_DEV_FLAGS_VPD_REF_F0. Previously, we set the flag on every
non-zero function of quirked devices. If a function turned out to be
different from function 0, i.e., it had a different class, vendor ID, or
device ID, the flag remained set but we didn't make VPD accessible at all.
Flip this around so we only set PCI_DEV_FLAGS_VPD_REF_F0 for functions that
are identical to function 0, and allow regular VPD access for any other
functions.
[bhelgaas: changelog, stable tag]
Fixes: 932c435caba8 ("PCI: Add dev_flags bit to access VPD through function 0")
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
Signed-off-by: Bjorn Helgaas <helgaas@...nel.org>
Acked-by: Myron Stowe <myron.stowe@...hat.com>
Acked-by: Mark Rustad <mark.d.rustad@...el.com>
CC: stable@...r.kernel.org
>
> drivers/pci/access.c | 22 ----------------------
> drivers/pci/quirks.c | 20 ++++++++++++++++++--
> 2 files changed, 18 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/pci/access.c b/drivers/pci/access.c
> index 5a5f0a7..59ac36f 100644
> --- a/drivers/pci/access.c
> +++ b/drivers/pci/access.c
> @@ -475,23 +475,6 @@ static const struct pci_vpd_ops pci_vpd_f0_ops = {
> .release = pci_vpd_pci22_release,
> };
>
> -static int pci_vpd_f0_dev_check(struct pci_dev *dev)
> -{
> - struct pci_dev *tdev = pci_get_slot(dev->bus,
> - PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
> - int ret = 0;
> -
> - if (!tdev)
> - return -ENODEV;
> - if (!tdev->vpd || !tdev->multifunction ||
> - dev->class != tdev->class || dev->vendor != tdev->vendor ||
> - dev->device != tdev->device)
> - ret = -ENODEV;
> -
> - pci_dev_put(tdev);
> - return ret;
> -}
> -
> int pci_vpd_pci22_init(struct pci_dev *dev)
> {
> struct pci_vpd_pci22 *vpd;
> @@ -500,12 +483,7 @@ int pci_vpd_pci22_init(struct pci_dev *dev)
> cap = pci_find_capability(dev, PCI_CAP_ID_VPD);
> if (!cap)
> return -ENODEV;
> - if (dev->dev_flags & PCI_DEV_FLAGS_VPD_REF_F0) {
> - int ret = pci_vpd_f0_dev_check(dev);
>
> - if (ret)
> - return ret;
> - }
> vpd = kzalloc(sizeof(*vpd), GFP_ATOMIC);
> if (!vpd)
> return -ENOMEM;
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 6a30252..b03373f 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -1907,11 +1907,27 @@ static void quirk_netmos(struct pci_dev *dev)
> DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_VENDOR_ID_NETMOS, PCI_ANY_ID,
> PCI_CLASS_COMMUNICATION_SERIAL, 8, quirk_netmos);
>
> +/*
> + * Quirk non-zero PCI functions to route VPD access through function 0 for
> + * devices that share VPD resources between functions. The functions are
> + * expected to be identical devices.
> + */
> static void quirk_f0_vpd_link(struct pci_dev *dev)
> {
> - if (!dev->multifunction || !PCI_FUNC(dev->devfn))
> + struct pci_dev *f0;
> +
> + if (!PCI_FUNC(dev->devfn))
> return;
> - dev->dev_flags |= PCI_DEV_FLAGS_VPD_REF_F0;
> +
> + f0 = pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
> + if (!f0)
> + return;
> +
> + if (f0->vpd && dev->class == f0->class &&
> + dev->vendor == f0->vendor && dev->device == f0->device)
> + dev->dev_flags |= PCI_DEV_FLAGS_VPD_REF_F0;
> +
> + pci_dev_put(f0);
> }
> DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_INTEL, PCI_ANY_ID,
> PCI_CLASS_NETWORK_ETHERNET, 8, quirk_f0_vpd_link);
>
> --
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