[PATCH 1/1] iommu/vt-d: Avoid WARNING in sva unbind path

[Lu Baolu <baolu.lu@linux.intel.com>]

The Intel IOMMU driver allows SVA on devices even if they do not support
PCI/PRI. Commit 39c20c4e83b9 ("iommu/vt-d: Only handle IOPF for SVA when
PRI is supported") modified the SVA bind path to allow this configuration
by skipping IOPF enablement when PRI is missing. However, it failed to
update the unbind path.

This creates an imbalance: the unbind path attempts to disable IOPF for
a device that never had it enabled, triggering a WARNING in
intel_iommu_disable_iopf():

 WARNING: drivers/iommu/intel/iommu.c:3475 at intel_iommu_disable_iopf+0x4f/0x90d
 Call Trace:
  <TASK>
  blocking_domain_set_dev_pasid+0x50/0x70
  iommu_detach_device_pasid+0x89/0xc0
  iommu_sva_unbind_device+0x73/0x150
  xe_vm_close_and_put+0x4d2/0x1200 [xe]

Fix this by bypassing IOPF operations for SVA domains on non-PRI hardware
in both the bind and unbind paths.

Fixes: 39c20c4e83b9 ("iommu/vt-d: Only handle IOPF for SVA when PRI is supported")
Cc: stable@vger.kernel.org
Reported-by: Nareshkumar Gollakoti <naresh.kumar.g@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.h | 11 +++++++++++
 drivers/iommu/intel/svm.c   | 12 ++++--------
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index ef145560aa98..775f1c4ae346 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1254,18 +1254,29 @@ void intel_iommu_disable_iopf(struct device *dev);
 static inline int iopf_for_domain_set(struct iommu_domain *domain,
 				      struct device *dev)
 {
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+
 	if (!domain || !domain->iopf_handler)
 		return 0;
 
+	/* SVA with non-IOMMU/PRI IOPF handling is allowed. */
+	if (domain->type == IOMMU_DOMAIN_SVA && !info->pri_supported)
+		return 0;
+
 	return intel_iommu_enable_iopf(dev);
 }
 
 static inline void iopf_for_domain_remove(struct iommu_domain *domain,
 					  struct device *dev)
 {
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+
 	if (!domain || !domain->iopf_handler)
 		return;
 
+	if (domain->type == IOMMU_DOMAIN_SVA && !info->pri_supported)
+		return;
+
 	intel_iommu_disable_iopf(dev);
 }
 
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 57cd1db7207a..fea10acd4f02 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -164,12 +164,9 @@ static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
 	if (IS_ERR(dev_pasid))
 		return PTR_ERR(dev_pasid);
 
-	/* SVA with non-IOMMU/PRI IOPF handling is allowed. */
-	if (info->pri_supported) {
-		ret = iopf_for_domain_replace(domain, old, dev);
-		if (ret)
-			goto out_remove_dev_pasid;
-	}
+	ret = iopf_for_domain_replace(domain, old, dev);
+	if (ret)
+		goto out_remove_dev_pasid;
 
 	/* Setup the pasid table: */
 	sflags = cpu_feature_enabled(X86_FEATURE_LA57) ? PASID_FLAG_FL5LP : 0;
@@ -184,8 +181,7 @@ static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
 
 	return 0;
 out_unwind_iopf:
-	if (info->pri_supported)
-		iopf_for_domain_replace(old, domain, dev);
+	iopf_for_domain_replace(old, domain, dev);
 out_remove_dev_pasid:
 	domain_remove_dev_pasid(domain, dev, pasid);
 	return ret;
-- 
2.43.0