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From: Ethan Zhao <haifeng.zhao@linux.intel.com>
To: bhelgaas@google.com,
	baolu.lu@linux.intel.com,
	dwmw2@infradead.org,
	will@kernel.org,
	robin.murphy@arm.com,
	lukas@wunner.de
Cc: linux-pci@vger.kernel.org,
	iommu@lists.linux.dev,
	linux-kernel@vger.kernel.org
Subject: [RFC PATCH v8 0/5] fix vt-d hard lockup when hotplug ATS capable device
Date: Tue, 26 Dec 2023 21:59:18 -0500
Message-Id: <20231227025923.536148-1-haifeng.zhao@linux.intel.com>
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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&2] only passed compiling on stable v6.7-rc6.                    
                                                                         
                                                                         
change log:                                                            
v8:
- add a patch to break the loop for timeout device-TLB invalidation, as
  Bjorn said there is possibility device just no reponse 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 device-TLB invalidation if target device is gone
  PCI: make pci_dev_is_disconnected() helper public for other drivers
  iommu/vt-d: don't issue device-TLB invalidate request when device is
    disconnected
  iommu/vt-d: don't loop for timeout device-TLB 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(-)

-- 
2.31.1