[PATCH 2/7] iommu/vt-d: Do not ignore context table copy failures

[Lu Baolu]

copy_translation_tables() currently logs copy_context_table() failures
but still returns success, so partial copy failures are silently ignored.

That means Intel IOMMU may run with only part of the old tables copied.
Then some old domain IDs may not be reserved, and later may be reused by
new domains. With stale hardware cache entries still around, this can
cause bad DMA translations, DMA faults, or domain aliasing.

Fix by aborting on the first context-table copy failure, freeing temporary
context-table pages, and returning an error so caller falls back to a
clean root table path.

Fixes: f93b4ac5929a ("iommu/vt-d: Use ida to manage domain id")
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel/iommu.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 2e3b3ab216f8..38e2a670df9a 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1591,7 +1591,7 @@ static int copy_translation_tables(struct intel_iommu *iommu)
 		if (ret) {
 			pr_err("%s: Failed to copy context table for bus %d\n",
 				iommu->name, bus);
-			continue;
+			goto err_free_ctxt_tbls;
 		}
 	}
 
@@ -1623,11 +1623,27 @@ static int copy_translation_tables(struct intel_iommu *iommu)
 	memunmap(old_rt);
 	return 0;
 
+err_free_ctxt_tbls:
+	/*
+	 * None of these tables have been linked into iommu->root_entry yet,
+	 * so they are unreachable and must be freed here.
+	 */
+	for (bus = 0; bus < ctxt_table_entries; bus++)
+		iommu_free_pages(ctxt_tbls[bus]);
+	kfree(ctxt_tbls);
 out_unmap:
 	memunmap(old_rt);
 err_free_bitmap:
 	bitmap_free(iommu->copied_tables);
 	iommu->copied_tables = NULL;
+
+	/*
+	 * Only reservations taken from the old context entries can be in the
+	 * ida at this point; no domain has been allocated on this IOMMU yet.
+	 * ida_destroy() empties it and leaves it ready for reuse.
+	 */
+	ida_destroy(&iommu->domain_ida);
+
 	return ret;
 }
 
-- 
2.43.0