[Qemu-devel] [PATCH v5] memory: do not notify for non inclusive overlap entry

[Yan Zhao <yan.y.zhao@intel.com>]

if an entry has non inclusive overlap with the notifier, print warning
message and do not do notification for it.

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: Eric Auger <eric.auger@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>

---
v5:
1. still using warn_report instead of "assert"
2. returning at the end to refuse notification for entry which has non
inclusive overlap with the notifier.
3. updated commit title and warning message.

v4:
1. modified commit title
2. using "assert" instead of printing warning message

v3:
refined code style and message format

v2:
1. added a local variable entry_end (Eric Auger)
2. using PRIx64 as format for address range in warning message
(Eric Auger)
---
 memory.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/memory.c b/memory.c
index 0a089a7..fe0d08d 100644
--- a/memory.c
+++ b/memory.c
@@ -1937,13 +1937,13 @@ void memory_region_notify_one(IOMMUNotifier *notifier,
                               IOMMUTLBEntry *entry)
 {
     IOMMUNotifierFlag request_flags;
+    hwaddr entry_end = entry->iova + entry->addr_mask;
 
     /*
      * Skip the notification if the notification does not overlap
      * with registered range.
      */
-    if (notifier->start > entry->iova + entry->addr_mask ||
-        notifier->end < entry->iova) {
+    if (notifier->start > entry_end || notifier->end < entry->iova) {
         return;
     }
 
@@ -1953,6 +1953,18 @@ void memory_region_notify_one(IOMMUNotifier *notifier,
         request_flags = IOMMU_NOTIFIER_UNMAP;
     }
 
+    if (entry->iova < notifier->start || entry_end > notifier->end) {
+        warn_report("IOMMUTLBEntry 0x%" PRIx64 " - 0x%" PRIx64
+                " has non inclusive overlap with notifier 0x%" PRIx64
+                " - 0x%" PRIx64 ". %s is not allowed."
+                " Try to divide it into smaller sections.",
+                entry->iova, entry_end,
+                notifier->start, notifier->end,
+                (request_flags == IOMMU_NOTIFIER_MAP) ?
+                "Mapping" : "Unmapping");
+        return;
+    }
+
     if (notifier->notifier_flags & request_flags) {
         notifier->notify(notifier, entry);
     }
-- 
2.7.4