[PATCH v3 1/1] virtio-pci: Add lookup subregion of VirtIOPCIRegion MR

[Gao Shiyuan]

Now virtio_address_space_lookup only lookup common/isr/device/notify
MR and exclude their subregions.

When VHOST_USER_PROTOCOL_F_HOST_NOTIFIER enable, the notify MR has
host-notifier subregions and we need use host-notifier MR to
notify the hardware accelerator directly instead of eventfd notify.

Further more, maybe common/isr/device MR also has subregions in
the future, so need memory_region_find for each MR incluing
their subregions.

Add lookup subregion of VirtIOPCIRegion MR instead of only lookup container MR.

Fixes: a93c8d8 ("virtio-pci: Replace modern_as with direct access to 
modern_bar")

Co-developed-by: Zuo Boqun <zuoboqun@baidu.com>
Signed-off-by: Gao Shiyuan <gaoshiyuan@baidu.com>
Signed-off-by: Zuo Boqun <zuoboqun@baidu.com>
---
 hw/virtio/virtio-pci.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

---
v2 -> v3:
* modify commit message
* remove unused variable and move mrs to the inner block
* replace error_report with assert

v1 -> v2:
* modify commit message
* replace direct iteration over subregions with memory_region_find.

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 524b63e5c7..4d832fe845 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -615,8 +615,12 @@ static MemoryRegion 
*virtio_address_space_lookup(VirtIOPCIProxy *proxy,
         reg = &proxy->regs[i];
         if (*off >= reg->offset &&
             *off + len <= reg->offset + reg->size) {
-            *off -= reg->offset;
-            return &reg->mr;
+            MemoryRegionSection mrs = memory_region_find(&reg->mr,
+                                        *off - reg->offset, len);
+            assert(mrs.mr);
+            *off = mrs.offset_within_region;
+            memory_region_unref(mrs.mr);
+            return mrs.mr;
         }
     }
 
-- 
2.39.3 (Apple Git-146)