diff options
| author | Lukas Wunner <lukas@wunner.de> | 2021-11-18 01:22:09 +0300 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2021-11-19 21:39:33 +0300 |
| commit | 23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12 (patch) | |
| tree | 7edc9691787622cb6f08f2cafb856f2b1d5a1e66 /drivers/pci/hotplug | |
| parent | fa55b7dcdc43c1aa1ba12bca9d2dd4318c2a0dbf (diff) | |
| download | linux-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.c | 7 |
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); |