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-rw-r--r--drivers/hv/hv_balloon.c33
1 files changed, 31 insertions, 2 deletions
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index d1b4a4624d81..4c605c70ebf9 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -590,6 +590,16 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
if (ret) {
pr_info("hot_add memory failed error is %d\n", ret);
+ if (ret == -EEXIST) {
+ /*
+ * This error indicates that the error
+ * is not a transient failure. This is the
+ * case where the guest's physical address map
+ * precludes hot adding memory. Stop all further
+ * memory hot-add.
+ */
+ do_hot_add = false;
+ }
has->ha_end_pfn -= HA_CHUNK;
has->covered_end_pfn -= processed_pfn;
break;
@@ -849,11 +859,30 @@ static void hot_add_req(struct work_struct *dummy)
rg_sz = region_size;
}
- resp.page_count = process_hot_add(pg_start, pfn_cnt,
- rg_start, rg_sz);
+ if (do_hot_add)
+ resp.page_count = process_hot_add(pg_start, pfn_cnt,
+ rg_start, rg_sz);
#endif
+ /*
+ * The result field of the response structure has the
+ * following semantics:
+ *
+ * 1. If all or some pages hot-added: Guest should return success.
+ *
+ * 2. If no pages could be hot-added:
+ *
+ * If the guest returns success, then the host
+ * will not attempt any further hot-add operations. This
+ * signifies a permanent failure.
+ *
+ * If the guest returns failure, then this failure will be
+ * treated as a transient failure and the host may retry the
+ * hot-add operation after some delay.
+ */
if (resp.page_count > 0)
resp.result = 1;
+ else if (!do_hot_add)
+ resp.result = 1;
else
resp.result = 0;

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