[PATCH v8 13/14] hw/cxl/cxl-mailbox-utils: Add superset extent release mailbox support

[nifan.cxl@gmail.com]

From: Fan Ni <fan.ni@samsung.com>

With the change, we extend the extent release mailbox command processing
to allow more flexible release. As long as the DPA range of the extent to
release is covered by accepted extent(s) in the device, the release can be
performed.

Tested-by: Svetly Todorov <svetly.todorov@memverge.com>
Reviewed-by: Gregory Price <gregory.price@memverge.com>
Signed-off-by: Fan Ni <fan.ni@samsung.com>
---
 hw/cxl/cxl-mailbox-utils.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 045bce8f74..ec8949ce7b 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -1704,6 +1704,13 @@ static CXLRetCode cxl_dc_extent_release_dry_run(CXLType3Dev *ct3d,
         dpa = in->updated_entries[i].start_dpa;
         len = in->updated_entries[i].len;
 
+        /* Check if the DPA range is not fully backed with valid extents */
+        if (!ct3_test_region_block_backed(ct3d, dpa, len)) {
+            ret = CXL_MBOX_INVALID_PA;
+            goto free_and_exit;
+        }
+
+        /* After this point, extent overflow is the only error can happen */
         while (len > 0) {
             QTAILQ_FOREACH(ent, updated_list, node) {
                 range_init_nofail(&range, ent->start_dpa, ent->len);
@@ -1718,14 +1725,7 @@ static CXLRetCode cxl_dc_extent_release_dry_run(CXLType3Dev *ct3d,
                     if (range_contains(&range, dpa + len - 1)) {
                         len2 = ent_start_dpa + ent_len - dpa - len;
                     } else {
-                        /*
-                         * TODO: we reject the attempt to remove an extent
-                         * that overlaps with multiple extents in the device
-                         * for now. We will allow it once superset release
-                         * support is added.
-                         */
-                        ret = CXL_MBOX_INVALID_PA;
-                        goto free_and_exit;
+                        dpa = ent_start_dpa + ent_len;
                     }
                     len_done = ent_len - len1 - len2;
 
@@ -1752,14 +1752,9 @@ static CXLRetCode cxl_dc_extent_release_dry_run(CXLType3Dev *ct3d,
                     }
 
                     len -= len_done;
-                    /* len == 0 here until superset release is added */
                     break;
                 }
             }
-            if (len) {
-                ret = CXL_MBOX_INVALID_PA;
-                goto free_and_exit;
-            }
         }
     }
 free_and_exit:
-- 
2.43.0