[PATCH 0/5] Fix DPC hotplug race and enhance error hanlding

Ethan Zhao
2020-09-25T02:35:51Z

This simple patch set fixed some serious security issues found when DPC
error injection and NVMe SSD hotplug brute force test were doing -- race
condition between DPC handler and pciehp, AER interrupt handlers, caused
system hang and system with DPC feature couldn't recover to normal
working state as expected (NVMe instance lost, mount operation hang,
race PCIe access caused uncorrectable errors reported alternativly etc).

With this patch set applied, stable 5.9-rc6 could pass the PCIe Gen4 NVMe
SSD brute force hotplug test with any time interval between hot-remove and
plug-in operation tens of times without any errors occur and system works
normal.

With this patch set applied, system with DPC feature could recover from
NON-FATAL and FATAL errors injection test and works as expected.

System works smoothly when errors happen while hotplug is doing, no
uncorrectable errors found.

Brute DPC error injection script:

for i in {0..100}
do
setpci -s 64:02.0 0x196.w=000a
setpci -s 65:00.0 0x04.w=0544
mount /dev/nvme0n1p1 /root/nvme
sleep 1
done

Other details see every commits description part.

This patch set could be applied to stable 5.9-rc6 directly.

Help to review and test.

Thanks,
Ethan

Ethan Zhao (5):
PCI: define a function to check and wait till port finish DPC handling
PCI: pciehp: check and wait port status out of DPC before handling
DLLSC and PDC
PCI/ERR: get device before call device driver to avoid null pointer
reference
PCI: only return true when dev io state is really changed
PCI/ERR: don't mix io state not changed and no driver together

drivers/pci/hotplug/pciehp_hpc.c | 4 +++-
drivers/pci/pci.h | 31 +++----------------------------
drivers/pci/pcie/err.c | 18 ++++++++++++++++--
include/linux/pci.h | 31 +++++++++++++++++++++++++++++++
4 files changed, 53 insertions(+), 31 deletions(-)

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2.18.4