disable FB

hc

2024-01-04 1543e317f1da31b75942316931e8f491a8920811

 kernel/drivers/iommu/intel/pasid.c
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@@ -24,7 +24,6 @@
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 /*
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  * Intel IOMMU system wide PASID name space:
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  */
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-static DEFINE_SPINLOCK(pasid_lock);
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 u32 intel_pasid_max_id = PASID_MAX;
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 int vcmd_alloc_pasid(struct intel_iommu *iommu, u32 *pasid)
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@@ -187,6 +186,9 @@
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 attach_out:
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 	device_attach_pasid_table(info, pasid_table);
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+	if (!ecap_coherent(info->iommu->ecap))
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+		clflush_cache_range(pasid_table->table, (1 << order) * PAGE_SIZE);
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+
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 	return 0;
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 }
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..
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@@ -259,19 +261,29 @@
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 	dir_index = pasid >> PASID_PDE_SHIFT;
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 	index = pasid & PASID_PTE_MASK;
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-	spin_lock(&pasid_lock);
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+retry:
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 	entries = get_pasid_table_from_pde(&dir[dir_index]);
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 	if (!entries) {
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 		entries = alloc_pgtable_page(info->iommu->node);
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-		if (!entries) {
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-			spin_unlock(&pasid_lock);
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+		if (!entries)
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 			return NULL;
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-		}
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-		WRITE_ONCE(dir[dir_index].val,
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-			   (u64)virt_to_phys(entries) | PASID_PTE_PRESENT);
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+		/*
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+		 * The pasid directory table entry won't be freed after
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+		 * allocation. No worry about the race with free and
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+		 * clear. However, this entry might be populated by others
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+		 * while we are preparing it. Use theirs with a retry.
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+		 */
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+		if (cmpxchg64(&dir[dir_index].val, 0ULL,
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+			      (u64)virt_to_phys(entries) | PASID_PTE_PRESENT)) {
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+			free_pgtable_page(entries);
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+			goto retry;
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+		}
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+		if (!ecap_coherent(info->iommu->ecap)) {
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+			clflush_cache_range(entries, VTD_PAGE_SIZE);
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+			clflush_cache_range(&dir[dir_index].val, sizeof(*dir));
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+		}
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 	}
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-	spin_unlock(&pasid_lock);
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 	return &entries[index];
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 }