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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




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@xxxxxxxxxxxxx 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(-)

How aobut refactor the qi_submit_sync() and qi_check_fault() like

following, combination of patch

[2] iommu/vt-d: break out ATS Invalidation if target device is gone

[5] iommu/vt-d: don't loop for timeout ATS Invalidation request forever

but sending them in seperated patches seems better ? each of them

handling different case.

- fold additional errors/fault/exception handling into qi_check_fault()

- the detetion of target device presence use to handle surprise removal

 or device died /no response.

- the ITE part use to break out the timeout ATS invalidation request,

  use to handle the case response time of device is too long.

- if passed invalid target_pdev, means this is ATS invalidation request.

- no error handling change in qi_submit_sync().


Please comment.


--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -1267,16 +1267,28 @@ static void qi_dump_fault(struct intel_iommu *iommu, u32 fault)
               (unsigned long long)desc->qw1);
 }

-static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index) +static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index,
+                  pci_dev *target_pdev)
 {
        u32 fault;
        int head, tail;
+       u64 iqe_err, ice_sid;
        struct q_inval *qi = iommu->qi;
        int shift = qi_shift(iommu);

        if (qi->desc_status[wait_index] == QI_ABORT)
                return -EAGAIN;

+       /*
+        * If the ATS invalidation target device is gone this moment (surprise
+        * removed, died, no response) don't try this request again. this
+        * request will not get valid result anymore. but the request was
+        * already submitted to hardware and we predict to get a ITE in
+        * followed batch of request, if so, it will get handled then.
+        */
+       if (target_pdev && !pci_device_is_present(target_pdev))
+               return -EINVAL;
+
        fault = readl(iommu->reg + DMAR_FSTS_REG);
        if (fault & (DMA_FSTS_IQE | DMA_FSTS_ITE | DMA_FSTS_ICE))
                qi_dump_fault(iommu, fault);
@@ -1315,6 +1327,13 @@ static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index)
                tail = readl(iommu->reg + DMAR_IQT_REG);
                tail = ((tail >> shift) - 1 + QI_LENGTH) % QI_LENGTH;

+               /*
+                * SID field is valid only when the ITE field is Set in FSTS_REG
+                * see Intel VT-d spec r4.1, section 11.4.9.9
+                */
+               iqe_err = dmar_readq(iommu->reg + DMAR_IQER_REG);
+               ice_sid = DMAR_IQER_REG_ITESID(iqe_err);
+
                writel(DMA_FSTS_ITE, iommu->reg + DMAR_FSTS_REG);
                pr_info("Invalidation Time-out Error (ITE) cleared\n");

@@ -1324,6 +1343,16 @@ static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index)
                        head = (head - 2 + QI_LENGTH) % QI_LENGTH;
                } while (head != tail);

+               /*
+                * If got ITE, we need to check if the sid of ITE is the same as +                * current ATS invalidation target device, if yes, don't try this +                * request anymore, the target device has a response time beyound +                * expected. 0 value of ice_sid means old device, no ice_sid value.
+                */
+               if (target_pdev && ice_sid && ice_sid ==
+                   pci_dev_id(pci_physfn(target_pdev))
+                               return -ETIMEDOUT;
+
                if (qi->desc_status[wait_index] == QI_ABORT)
                        return -EAGAIN;
        }
@@ -1344,7 +1373,7 @@ static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index)
  * can be part of the submission but it will not be polled for completion.
  */
 int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc,
-                  unsigned int count, unsigned long options)
+                  unsigned int count, unsigned long options, pci_dev *target_pdev)
 {
        struct q_inval *qi = iommu->qi;
        s64 devtlb_start_ktime = 0;
@@ -1430,7 +1459,7 @@ int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc,                  * a deadlock where the interrupt context can wait indefinitely
                 * for free slots in the queue.
                 */
-               rc = qi_check_fault(iommu, index, wait_index);
+               rc = qi_check_fault(iommu, index, wait_index, target_pdev);
                if (rc)
                        break;


Thanks,

Ethan






[Index of Archives]     [DMA Engine]     [Linux Coverity]     [Linux USB]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Greybus]

  Powered by Linux