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

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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>
This commit is contained in:
Bjorn Helgaas 2016-11-28 16:43:06 -06:00
parent 6ffa2489c5
commit 546ba9f8f2
1 changed files with 8 additions and 0 deletions
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8
drivers/pci/iov.c
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@ -584,6 +584,7 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno)
struct resource *res = dev->resource + resno; struct resource *res = dev->resource + resno;
int vf_bar = resno - PCI_IOV_RESOURCES; int vf_bar = resno - PCI_IOV_RESOURCES;
struct pci_bus_region region; struct pci_bus_region region;
u16 cmd;
u32 new; u32 new;
int reg; int reg;
@ -595,6 +596,13 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno)
if (!iov) if (!iov)
return; 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 * Ignore unimplemented BARs, unused resource slots for 64-bit
* BARs, and non-movable resources, e.g., those described via * BARs, and non-movable resources, e.g., those described via