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authorSubbaraya Sundeep <sbhatta@marvell.com>2019-11-04 12:27:44 +0530
committerBjorn Helgaas <bhelgaas@google.com>2019-11-14 15:02:10 -0600
commit73884a7082f466ce6686bb8dd7e6571dd42313b4 (patch)
tree9a81a92c5af1caf203f749c6dc160c7038bb851f
parentc13704f5685deb7d6eb21e293233e0901ed77377 (diff)
downloadlinux-73884a7082f466ce6686bb8dd7e6571dd42313b4.tar.bz2
PCI: Do not use bus number zero from EA capability
As per PCIe r5.0, sec 7.8.5.2, fixed bus numbers of a bridge must be zero when no function that uses EA is located behind it. Hence, if EA supplies bus numbers of zero, assign bus numbers normally. A secondary bus can never have a bus number of zero, so setting a bridge's Secondary Bus Number to zero makes downstream devices unreachable. [bhelgaas: retain bool return value so "zero is invalid" logic is local] Fixes: 2dbce5901179 ("PCI: Assign bus numbers present in EA capability for bridges") Link: https://lore.kernel.org/r/1572850664-9861-1-git-send-email-sundeep.lkml@gmail.com Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: stable@vger.kernel.org # v5.2+
-rw-r--r--drivers/pci/probe.c16
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index bdbc8490f962..d3033873395d 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1090,14 +1090,15 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
* @sec: updated with secondary bus number from EA
* @sub: updated with subordinate bus number from EA
*
- * If @dev is a bridge with EA capability, update @sec and @sub with
- * fixed bus numbers from the capability and return true. Otherwise,
- * return false.
+ * If @dev is a bridge with EA capability that specifies valid secondary
+ * and subordinate bus numbers, return true with the bus numbers in @sec
+ * and @sub. Otherwise return false.
*/
static bool pci_ea_fixed_busnrs(struct pci_dev *dev, u8 *sec, u8 *sub)
{
int ea, offset;
u32 dw;
+ u8 ea_sec, ea_sub;
if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE)
return false;
@@ -1109,8 +1110,13 @@ static bool pci_ea_fixed_busnrs(struct pci_dev *dev, u8 *sec, u8 *sub)
offset = ea + PCI_EA_FIRST_ENT;
pci_read_config_dword(dev, offset, &dw);
- *sec = dw & PCI_EA_SEC_BUS_MASK;
- *sub = (dw & PCI_EA_SUB_BUS_MASK) >> PCI_EA_SUB_BUS_SHIFT;
+ ea_sec = dw & PCI_EA_SEC_BUS_MASK;
+ ea_sub = (dw & PCI_EA_SUB_BUS_MASK) >> PCI_EA_SUB_BUS_SHIFT;
+ if (ea_sec == 0 || ea_sub < ea_sec)
+ return false;
+
+ *sec = ea_sec;
+ *sub = ea_sub;
return true;
}