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Date: Mon, 13 Jul 2015 11:40:02 -0700
From: Mark D Rustad <mark.d.rustad@...el.com>
To: bhelgaas@...gle.com
Cc: linux-pci@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
netdev@...r.kernel.org
Subject: [PATCH V4 1/2] pci: Add dev_flags bit to access VPD through
function 0
From: Mark Rustad <mark.d.rustad@...el.com>
Add a dev_flags bit, PCI_DEV_FLAGS_VPD_REF_F0, to access VPD through
function 0 to provide VPD access on other functions. This is for
hardware devices that provide copies of the same VPD capability
registers in multiple functions. Because the kernel expects that
each function has its own registers, both the locking and the state
tracking are affected by VPD accesses to different functions.
On such devices for example, if a VPD write is performed on function
0, *any* later attempt to read VPD from any other function of that
device will hang. This has to do with how the kernel tracks the
expected value of the F bit per function.
Concurrent accesses to different functions of the same device can
not only hang but also corrupt both read and write VPD data.
When hangs occur, typically the error message:
vpd r/w failed. This is likely a firmware bug on this device.
will be seen.
Never set this bit on function 0 or there will be an infinite recursion.
Signed-off-by: Mark Rustad <mark.d.rustad@...el.com>
---
Changes in V2:
- Corrected spelling in log message
- Added checks to see that the referenced function 0 is reasonable
Changes in V3:
- Don't leak a device reference
- Check that function 0 has VPD
- Make a helper for the function 0 checks
- Do multifunction check in the quirk
Changes in V4:
- Provide a much more detailed explanation in the commit log
---
drivers/pci/access.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++-
include/linux/pci.h | 2 ++
2 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index d9b64a175990..b965c12168b7 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -439,6 +439,56 @@ static const struct pci_vpd_ops pci_vpd_pci22_ops = {
.release = pci_vpd_pci22_release,
};
+static ssize_t pci_vpd_f0_read(struct pci_dev *dev, loff_t pos, size_t count,
+ void *arg)
+{
+ struct pci_dev *tdev = pci_get_slot(dev->bus, PCI_SLOT(dev->devfn));
+ ssize_t ret;
+
+ if (!tdev)
+ return -ENODEV;
+
+ ret = pci_read_vpd(tdev, pos, count, arg);
+ pci_dev_put(tdev);
+ return ret;
+}
+
+static ssize_t pci_vpd_f0_write(struct pci_dev *dev, loff_t pos, size_t count,
+ const void *arg)
+{
+ struct pci_dev *tdev = pci_get_slot(dev->bus, PCI_SLOT(dev->devfn));
+ ssize_t ret;
+
+ if (!tdev)
+ return -ENODEV;
+
+ ret = pci_write_vpd(tdev, pos, count, arg);
+ pci_dev_put(tdev);
+ return ret;
+}
+
+static const struct pci_vpd_ops pci_vpd_f0_ops = {
+ .read = pci_vpd_f0_read,
+ .write = pci_vpd_f0_write,
+ .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_SLOT(dev->devfn));
+ 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;
@@ -447,12 +497,21 @@ 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;
vpd->base.len = PCI_VPD_PCI22_SIZE;
- vpd->base.ops = &pci_vpd_pci22_ops;
+ if (dev->dev_flags & PCI_DEV_FLAGS_VPD_REF_F0)
+ vpd->base.ops = &pci_vpd_f0_ops;
+ else
+ vpd->base.ops = &pci_vpd_pci22_ops;
mutex_init(&vpd->lock);
vpd->cap = cap;
vpd->busy = false;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 8a0321a8fb59..8edb125db13a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -180,6 +180,8 @@ enum pci_dev_flags {
PCI_DEV_FLAGS_NO_BUS_RESET = (__force pci_dev_flags_t) (1 << 6),
/* Do not use PM reset even if device advertises NoSoftRst- */
PCI_DEV_FLAGS_NO_PM_RESET = (__force pci_dev_flags_t) (1 << 7),
+ /* Get VPD from function 0 VPD */
+ PCI_DEV_FLAGS_VPD_REF_F0 = (__force pci_dev_flags_t) (1 << 8),
};
enum pci_irq_reroute_variant {
--
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