[for-4.4,09/19] PCI: Don't update VF BARs while VF memory space is enabled

Message ID 1490458699-24484-10-git-send-email-sumit.semwal@linaro.org
State New
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  • Stable commits from Ubuntu Yakkety 4.9-lts
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Commit Message

Sumit Semwal March 25, 2017, 4:18 p.m.
From: Bjorn Helgaas <bhelgaas@google.com>

[ Upstream commit 546ba9f8f22f71b0202b6ba8967be5cc6dae4e21 ]

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

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>

Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

 drivers/pci/iov.c | 8 ++++++++
 1 file changed, 8 insertions(+)



diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 2f8ea6f..47c46d0 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -567,6 +567,7 @@  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;
@@ -578,6 +579,13 @@  void pci_iov_update_resource(struct pci_dev *dev, int resno)
 	if (!iov)
+	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