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@xxxxxxxxxx>
---
drivers/pci/iov.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index d00ed5c..a800ba2 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -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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