PCI: Avoid FLR for Intel 82579 NICs

Per Intel Specification Update 335553-002 (see link below), some 82579
network adapters advertise a Function Level Reset (FLR) capability, but
they can hang when an FLR is triggered.

To reproduce the problem, attach the device to a VM, then detach and try to
attach again.

Add a quirk to prevent the use of FLR on these devices.

[bhelgaas: changelog, comments]
Link: http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/82579lm-82579v-gigabit-network-connection-spec-update.pdf
Signed-off-by: Sasha Neftin <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>

drivers/pci/pci.c

···
 	if (!(cap & PCI_EXP_DEVCAP_FLR))
 		return -ENOTTY;
 
+	if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
+		return -ENOTTY;
+
 	if (probe)
 		return 0;
 
···
 
 	pos = pci_find_capability(dev, PCI_CAP_ID_AF);
 	if (!pos)
+		return -ENOTTY;
+
+	if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
 		return -ENOTTY;
 
 	pci_read_config_byte(dev, pos + PCI_AF_CAP, &cap);

drivers/pci/quirks.c

···
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2031, quirk_no_aersid);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2032, quirk_no_aersid);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2033, quirk_no_aersid);
+
+/* FLR may cause some 82579 devices to hang. */
+static void quirk_intel_no_flr(struct pci_dev *dev)
+{
+	dev->dev_flags |= PCI_DEV_FLAGS_NO_FLR_RESET;
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_intel_no_flr);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_intel_no_flr);

include/linux/pci.h

···
 	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),
+	/* Do not use FLR even if device advertises PCI_AF_CAP */
+	PCI_DEV_FLAGS_NO_FLR_RESET = (__force pci_dev_flags_t) (1 << 10),
 };
 
 enum pci_irq_reroute_variant {