From: Sumit Semwal sumit.semwal@linaro.org
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ 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 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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- drivers/pci/iov.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 06959425cdea..846d4f604ebd 100644 --- a/drivers/pci/iov.c +++ b/drivers/pci/iov.c @@ -564,6 +564,7 @@ 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;
@@ -575,6 +576,13 @@ 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