[RFC PATCH v8 0/5] fix vt-d hard lockup when hotplug ATS capable device

Ethan Zhao
2023-12-28T00:16:52Z

This patchset is used to fix vt-d hard lockup reported when surprise
unplug ATS capable endpoint device connects to system via PCIe switch
as following topology.

+-[0000:15]-+-00.0 Intel Corporation Ice Lake Memory Map/VT-d
| +-00.1 Intel Corporation Ice Lake Mesh 2 PCIe
| +-00.2 Intel Corporation Ice Lake RAS
| +-00.4 Intel Corporation Device 0b23
| \-01.0-[16-1b]----00.0-[17-1b]--+-00.0-[18]----00.0
NVIDIA Corporation Device 2324
| +-01.0-[19]----00.0
Mellanox Technologies MT2910 Family [ConnectX-7]

User brought endpoint device 19:00.0's link down by flapping it's hotplug
capable slot 17:01.0 link control register, as sequence DLLSC response,
pciehp_ist() will unload device driver and power it off, durning device
driver is unloading an iommu device-TLB invalidation (Intel VT-d spec, or
'ATS Invalidation' in PCIe spec) request issued to that link down device,
thus a long time completion/timeout waiting in interrupt context causes
continuous hard lockup warnning and system hang.

Other detail, see every patch commit log.

patch [3&4] were tested by yehaorong@bytedance.com on stable v6.7-rc4.
patch [1-5] passed compiling on stable v6.7-rc6.

change log:
v9:
- unify all spelling of ATS Invalidation adhere to PCIe spec per Bjorn's
suggestion.
v8:
- add a patch to break the loop for timeout device-TLB invalidation, as
Bjorn said there is possibility device just no response but not gone.
v7:
- reorder patches and revise commit log per Bjorn's guide.
- other code and commit log revise per Lukas' suggestion.
- rebased to stable v6.7-rc6.
v6:
- add two patches to break out device-TLB invalidation if device is gone.
v5:
- add a patch try to fix the rare case (surprise remove a device in
safe removal process). not work because surprise removal handling can't
re-enter when another safe removal is in process.
v4:
- move the PCI device state checking after ATS per Baolu's suggestion.
v3:
- fix commit description typo.
v2:
- revise commit[1] description part according to Lukas' suggestion.
- revise commit[2] description to clarify the issue's impact.
v1:
- https://lore.kernel.org/lkml/20231213034637.2603013-1-haifeng.zhao@
linux.intel.com/T/

Thanks,
Ethan

Ethan Zhao (5):
iommu/vt-d: add flush_target_dev member to struct intel_iommu and pass
device info to all ATS Invalidation functions
iommu/vt-d: break out ATS Invalidation if target device is gone
PCI: make pci_dev_is_disconnected() helper public for other drivers
iommu/vt-d: don't issue ATS Invalidation request when device is
disconnected
iommu/vt-d: don't loop for timeout ATS Invalidation request
forever

drivers/iommu/intel/dmar.c | 14 +++++++++++++-
drivers/iommu/intel/iommu.c | 1 +
drivers/iommu/intel/iommu.h | 2 ++
drivers/iommu/intel/pasid.c | 4 ++++
drivers/iommu/intel/svm.c | 1 +
drivers/pci/pci.h | 5 -----
include/linux/pci.h | 5 +++++
7 files changed, 26 insertions(+), 6 deletions(-)

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2.31.1