iommu/vt-d: Clean up unused PASID updating functions

update_pasid() and its call chain are currently unused in the tree because
Thomas disabled the ENQCMD feature. The feature will be re-enabled shortly
using a different approach and update_pasid() and its call chain will not
be used in the new approach.

Remove the useless functions.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20210920192349.2602141-1-fenghua.yu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20211014053839.727419-8-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: Fenghua Yu

arch/x86/include/asm/fpu/api.h

@@ -106,6 +106,4 @@ extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
  */
 #define PASID_DISABLED	0
 
-static inline void update_pasid(void) { }
-
 #endif /* _ASM_X86_FPU_API_H */

drivers/iommu/intel/svm.c

@@ -505,21 +505,6 @@ int intel_svm_unbind_gpasid(struct device *dev, u32 pasid)
 	return ret;
 }
 
-static void _load_pasid(void *unused)
-{
-	update_pasid();
-}
-
-static void load_pasid(struct mm_struct *mm, u32 pasid)
-{
-	mutex_lock(&mm->context.lock);
-
-	/* Update PASID MSR on all CPUs running the mm's tasks. */
-	on_each_cpu_mask(mm_cpumask(mm), _load_pasid, NULL, true);
-
-	mutex_unlock(&mm->context.lock);
-}
-
 static int intel_svm_alloc_pasid(struct device *dev, struct mm_struct *mm,
 				 unsigned int flags)
 {
@@ -614,10 +599,6 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 	if (ret)
 		goto free_sdev;
 
-	/* The newly allocated pasid is loaded to the mm. */
-	if (!(flags & SVM_FLAG_SUPERVISOR_MODE) && list_empty(&svm->devs))
-		load_pasid(mm, svm->pasid);
-
 	list_add_rcu(&sdev->list, &svm->devs);
 success:
 	return &sdev->sva;
@@ -670,11 +651,8 @@ static int intel_svm_unbind_mm(struct device *dev, u32 pasid)
 			kfree_rcu(sdev, rcu);
 
 			if (list_empty(&svm->devs)) {
-				if (svm->notifier.ops) {
+				if (svm->notifier.ops)
 					mmu_notifier_unregister(&svm->notifier, mm);
-					/* Clear mm's pasid. */
-					load_pasid(mm, PASID_DISABLED);
-				}
 				pasid_private_remove(svm->pasid);
 				/* We mandate that no page faults may be outstanding
 				 * for the PASID when intel_svm_unbind_mm() is called.