linux-kernel - Re: [RFC PATCH v10 0/5] fix vt-d hard lockup when hotplug ATS capable device

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Date: Tue, 9 Jan 2024 09:24:05 +0800
From: Ethan Zhao <haifeng.zhao@...ux.intel.com>
To: kevin.tian@...el.com, bhelgaas@...gle.com, baolu.lu@...ux.intel.com,
 dwmw2@...radead.org, will@...nel.org, robin.murphy@....com, lukas@...ner.de
Cc: linux-pci@...r.kernel.org, iommu@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v10 0/5] fix vt-d hard lockup when hotplug ATS capable
 device


On 12/29/2023 1:02 AM, Ethan Zhao wrote:
> 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@...edance.com on stable v6.7-rc4.
> patch [1-5] passed compiling on stable v6.7-rc6.
>                                                                           
>                                                                           
> change log:
> v10:
> - refactor qi_submit_sync() and its callers to get pci_dev instance, as
>    Kevin pointed out add target_flush_dev to iommu is not right.
> 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 pci_dev parameter to qi_submit_sync and refactor
>      callers
>    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          | 55 ++++++++++++++++++++++-------
>   drivers/iommu/intel/iommu.c         | 26 ++++----------
>   drivers/iommu/intel/iommu.h         | 17 +++++----
>   drivers/iommu/intel/irq_remapping.c |  2 +-
>   drivers/iommu/intel/pasid.c         | 13 +++----
>   drivers/iommu/intel/svm.c           | 13 ++++---
>   drivers/pci/pci.h                   |  5 ---
>   include/linux/pci.h                 |  5 +++
>   8 files changed, 74 insertions(+), 62 deletions(-)

Any new comment for this patchset ?


Thanks,

Ethan