[Qemu-devel] [PATCH] memory: warning on out of scope notification

[Yan Zhao]

if an entry has parts out of scope of notifier's range, print warning
message.

Out of scope mapping/unmapping would cause problem, as in below case:

1. initially there are two notifiers with ranges
0-0xfedfffff, 0xfef00000-0xffffffffffffffff,
IOVAs from 0x3c000000 - 0x3c1fffff is in shadow page table.

2. in vfio, memory_region_register_iommu_notifier() is followed by
memory_region_iommu_replay(), which will first call address space
unmap,
and walk and add back all entries in vtd shadow page table. e.g.
(1) for notifier 0-0xfedfffff,
    IOVAs from 0 - 0xffffffff get unmapped,
    and IOVAs from 0x3c000000 - 0x3c1fffff get mapped
(2) for notifier 0xfef00000-0xffffffffffffffff
    IOVAs from 0 - 0x7fffffffff get unmapped,
    but IOVAs from 0x3c000000 - 0x3c1fffff cannot get mapped back.

Cc: Auger Eric <address@hidden>
Signed-off-by: Yan Zhao <address@hidden>
---
 memory.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/memory.c b/memory.c
index 0a089a7..18927f2 100644
--- a/memory.c
+++ b/memory.c
@@ -1953,6 +1953,16 @@ void memory_region_notify_one(IOMMUNotifier *notifier,
         request_flags = IOMMU_NOTIFIER_UNMAP;
     }
 
+    if (entry->iova < notifier->start ||
+            entry->iova + entry->addr_mask > notifier->end) {
+        warn_report("%s IOMMUTLBEntry %lx-%lx outside of "
+                "notifier scope %lx-%lx",
+                (request_flags == IOMMU_NOTIFIER_MAP) ?
+                "Mapping" : "Unmapping",
+                entry->iova, entry->iova + entry->addr_mask,
+                notifier->start, notifier->end);
+    }
+
     if (notifier->notifier_flags & request_flags) {
         notifier->notify(notifier, entry);
     }
-- 
2.7.4