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authorBjorn Helgaas <bhelgaas@google.com>2012-07-10 05:49:37 +0400
committerBjorn Helgaas <bhelgaas@google.com>2012-07-10 05:50:53 +0400
commit9aac537e0e33f4e4f28b8e7472c283fb6460c650 (patch)
tree0e27b819f093360a0e028b0af20ee8ae6ad949f3
parentbbffe435248444065bd76141c41bbe65db950cc9 (diff)
downloadlinux-9aac537e0e33f4e4f28b8e7472c283fb6460c650.tar.xz
PCI: disable MEM decoding while updating 64-bit MEM BARs
When we update 64-bit BARs, we have to perform two config writes. Between the writes, the half-written BAR value could match a MEM access intended for another device. This could result in corruption of this device (for writes) or an unexpected response machine check (for reads). To prevent this, disable MEM decoding while updating such BARs. This uses the same safety test as 253d2e5498, which disables both MEM and IO while sizing BARs, namely, we don't disable decoding for host bridge devices. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
-rw-r--r--drivers/pci/setup-res.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index eea85dafc763..1a0e60e265ea 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -30,6 +30,8 @@
void pci_update_resource(struct pci_dev *dev, int resno)
{
struct pci_bus_region region;
+ bool disable;
+ u16 cmd;
u32 new, check, mask;
int reg;
enum pci_bar_type type;
@@ -67,6 +69,18 @@ void pci_update_resource(struct pci_dev *dev, int resno)
new |= PCI_ROM_ADDRESS_ENABLE;
}
+ /*
+ * We can't update a 64-bit BAR atomically, so when possible,
+ * disable decoding so that a half-updated BAR won't conflict
+ * with another device.
+ */
+ disable = (res->flags & IORESOURCE_MEM_64) && !dev->mmio_always_on;
+ if (disable) {
+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
+ pci_write_config_word(dev, PCI_COMMAND,
+ cmd & ~PCI_COMMAND_MEMORY);
+ }
+
pci_write_config_dword(dev, reg, new);
pci_read_config_dword(dev, reg, &check);
@@ -84,6 +98,10 @@ void pci_update_resource(struct pci_dev *dev, int resno)
"(high %#08x != %#08x)\n", resno, new, check);
}
}
+
+ if (disable)
+ pci_write_config_word(dev, PCI_COMMAND, cmd);
+
res->flags &= ~IORESOURCE_UNSET;
dev_dbg(&dev->dev, "BAR %d: set to %pR (PCI address [%#llx-%#llx])\n",
resno, res, (unsigned long long)region.start,