Commit 546ba9f8 authored Nov 28, 2016 by Bjorn Helgaas

PCI: Don't update VF BARs while VF memory space is enabled



If we update a VF BAR while it's enabled, there are two potential problems:

  1) Any driver that's using the VF has a cached BAR value that is stale
     after the update, and

  2) We can't update 64-bit BARs atomically, so the intermediate state
     (new lower dword with old upper dword) may conflict with another
     device, and an access by a driver unrelated to the VF may cause a bus
     error.

Warn about attempts to update VF BARs while they are enabled.  This is a
programming error, so use dev_WARN() to get a backtrace.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>

parent 6ffa2489

drivers/pci/iov.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -584,6 +584,7 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno)
		struct resource *res = dev->resource + resno;
		int vf_bar = resno - PCI_IOV_RESOURCES;
		struct pci_bus_region region;
		u16 cmd;
		u32 new;
		int reg;

		@@ -595,6 +596,13 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno)
		if (!iov)
		return;

		pci_read_config_word(dev, iov->pos + PCI_SRIOV_CTRL, &cmd);
		if ((cmd & PCI_SRIOV_CTRL_VFE) && (cmd & PCI_SRIOV_CTRL_MSE)) {
		dev_WARN(&dev->dev, "can't update enabled VF BAR%d %pR\n",
		vf_bar, res);
		return;
		}

		/*
		* Ignore unimplemented BARs, unused resource slots for 64-bit
		* BARs, and non-movable resources, e.g., those described via

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