[PATCH v4 2/5] PCI: Ignore enforced alignment to VF BARs

Yongji Xie xyjxie at linux.vnet.ibm.com
Fri Aug 12 15:42:23 AEST 2016

VF BARs are read-only zeroes according to SRIOV spec,
the normal way(writing BARs) of allocating resources wouldn't
be applied to VFs. The VFs' resources would be allocated
when we enable SR-IOV capability. So we should not try to
reassign alignment after we enable VFs. It's meaningless
and will release the allocated resources which leads to a bug.

Signed-off-by: Yongji Xie <xyjxie at linux.vnet.ibm.com>
 drivers/pci/pci.c |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2d85a96..b8357d7 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5048,6 +5048,15 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
 	resource_size_t align, size;
 	u16 command;
+	/*
+	 * VF BARs are RO zero according to SR-IOV spec Their
+	 * resources would be allocated when we enable them and not be
+	 * re-allocated any more. So we should never try to reassign
+	 * VF's alignment here.
+	 */
+	if (dev->is_virtfn)
+		return;
 	/* check if specified PCI is target device to reassign */
 	align = pci_specified_resource_alignment(dev);
 	if (!align)

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