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authorLukas Wunner <lukas@wunner.de>2021-11-18 01:22:09 +0300
committerBjorn Helgaas <bhelgaas@google.com>2021-11-19 21:39:33 +0300
commit23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12 (patch)
tree7edc9691787622cb6f08f2cafb856f2b1d5a1e66 /drivers/pci/hotplug
parentfa55b7dcdc43c1aa1ba12bca9d2dd4318c2a0dbf (diff)
downloadlinux-23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12.tar.xz
PCI: pciehp: Fix infinite loop in IRQ handler upon power fault
The Power Fault Detected bit in the Slot Status register differs from all other hotplug events in that it is sticky: It can only be cleared after turning off slot power. Per PCIe r5.0, sec. 6.7.1.8: If a power controller detects a main power fault on the hot-plug slot, it must automatically set its internal main power fault latch [...]. The main power fault latch is cleared when software turns off power to the hot-plug slot. The stickiness used to cause interrupt storms and infinite loops which were fixed in 2009 by commits 5651c48cfafe ("PCI pciehp: fix power fault interrupt storm problem") and 99f0169c17f3 ("PCI: pciehp: enable software notification on empty slots"). Unfortunately in 2020 the infinite loop issue was inadvertently reintroduced by commit 8edf5332c393 ("PCI: pciehp: Fix MSI interrupt race"): The hardirq handler pciehp_isr() clears the PFD bit until pciehp's power_fault_detected flag is set. That happens in the IRQ thread pciehp_ist(), which never learns of the event because the hardirq handler is stuck in an infinite loop. Fix by setting the power_fault_detected flag already in the hardirq handler. Link: https://bugzilla.kernel.org/show_bug.cgi?id=214989 Link: https://lore.kernel.org/linux-pci/DM8PR11MB5702255A6A92F735D90A4446868B9@DM8PR11MB5702.namprd11.prod.outlook.com Fixes: 8edf5332c393 ("PCI: pciehp: Fix MSI interrupt race") Link: https://lore.kernel.org/r/66eaeef31d4997ceea357ad93259f290ededecfd.1637187226.git.lukas@wunner.de Reported-by: Joseph Bao <joseph.bao@intel.com> Tested-by: Joseph Bao <joseph.bao@intel.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: stable@vger.kernel.org # v4.19+ Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Diffstat (limited to 'drivers/pci/hotplug')
-rw-r--r--drivers/pci/hotplug/pciehp_hpc.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 83a0fa119cae..9535c61cbff3 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -642,6 +642,8 @@ read_status:
*/
if (ctrl->power_fault_detected)
status &= ~PCI_EXP_SLTSTA_PFD;
+ else if (status & PCI_EXP_SLTSTA_PFD)
+ ctrl->power_fault_detected = true;
events |= status;
if (!events) {
@@ -651,7 +653,7 @@ read_status:
}
if (status) {
- pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, events);
+ pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, status);
/*
* In MSI mode, all event bits must be zero before the port
@@ -725,8 +727,7 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id)
}
/* Check Power Fault Detected */
- if ((events & PCI_EXP_SLTSTA_PFD) && !ctrl->power_fault_detected) {
- ctrl->power_fault_detected = 1;
+ if (events & PCI_EXP_SLTSTA_PFD) {
ctrl_err(ctrl, "Slot(%s): Power fault\n", slot_name(ctrl));
pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF,
PCI_EXP_SLTCTL_ATTN_IND_ON);