Re: [RFC PATCH v5 3/3] iommu/vt-d: abort the devTLB invalidation waiting if device is removed

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On 12/23/2023 7:35 AM, Ethan Zhao wrote:

On 12/22/2023 6:41 PM, Ethan Zhao wrote:
Even the devTLB invalidation request is just submitted and waiting it
to be done/timeout in qi_submit_sync(), it is possible device is removed
or powered-off. try to break it out in such rare but possible case.

This patch is sent for more comment. not tested, only passed compiling.

Signed-off-by: Ethan Zhao <haifeng.zhao@xxxxxxxxxxxxxxx>
---
  drivers/iommu/intel/dmar.c  |  3 ++-
  drivers/iommu/intel/iommu.c | 36 ++++++++++++++++++++++++++++++++++++
  2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index 23cb80d62a9a..d8637ab93387 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -1422,7 +1422,8 @@ int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc,
       */
      writel(qi->free_head << shift, iommu->reg + DMAR_IQT_REG);
  -    while (qi->desc_status[wait_index] != QI_DONE) {
+    while (qi->desc_status[wait_index] != QI_DONE &&
+            qi->desc_status[wait_index] != QI_ABORT) {

Another way is checking pci_device_is_present() here and bail out,

how about it ?

          /*
           * We will leave the interrupts disabled, to prevent interrupt
           * context to queue another cmd while a cmd is already submitted
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 897159dba47d..33075d0688bc 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4472,10 +4472,46 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev)
      return &iommu->iommu;
  }
  +static void intel_iommu_abort_devtlib_invalidate(struct device *dev)
+{
+    struct device_domain_info *info = dev_iommu_priv_get(dev);
+    struct intel_iommu *iommu = info->iommu;
+    struct q_inval *qi = iommu->qi;
+    struct qi_desc *desc, *idesc;
+    int index, offset, shift;
+    u16 sid, qdep, pfsid
+    unsigned long flags;
+
+    if (!dev_is_pci(info->dev) || !info->ats_enabled || !qi)
+        return;
+    if (!pci_dev_is_disconnected(to_pci_dev(dev)))
+        return;
+
+    sid = info->bus << 8 | info->devfn;
+    qdep = info->ats_qdep;
+    pfsid = info->pfsid;
+
+    raw_spin_lock_irqsave(&qi->q_lock, flags);
+    for (index = 1; index < QI_LENGTH; index++) {
+        offset = index << shift;
+        desc = qi->desc + offset;
+        if (desc->qw0 & QI_IWD_TYPE) {
+            offset = (index-1) << shift;
+            idesc = qi->desc + offset;
+            if (idesc->qw0 & QI_DEV_EIOTLB_SID(sid)) {
+                if (qi->desc_status[index] == QI_IN_USE)
+                    qi->desc_status[index] = QI_ABORT;
+            }
+        }
+    }
+    raw_spin_unlock_irqrestore(&qi->q_lock, flags);
+
+}
  static void intel_iommu_release_device(struct device *dev)
  {
      struct device_domain_info *info = dev_iommu_priv_get(dev);
  +    intel_iommu_abort_devtlib_invalidate(dev);

Wonder if there is lock something prevent pciehp_ist() supprise_removal

pci_lock_rescan_remove() will block another thread to re-enter the function

pci_stop_and_remove_bus_device() to get here, this patch doesn't work.



interrupt response re-enter to get here when another safe_removal is in process,

if so ,  see above

      dmar_remove_one_dev_info(dev);
      intel_pasid_free_table(dev);
      intel_iommu_debugfs_remove_dev(info);





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