[PATCH v6 2/3] hw/vfio: drop guest writes to ro regions

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

for vfio regions that are without write permission,
drop guest writes to those regions.

Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Xin Zeng <xin.zeng@intel.com>
---
 hw/vfio/common.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 0b3593b3c0..2a4fedfeaa 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -38,6 +38,7 @@
 #include "sysemu/reset.h"
 #include "trace.h"
 #include "qapi/error.h"
+#include "qemu/log.h"
 
 VFIOGroupList vfio_group_list =
     QLIST_HEAD_INITIALIZER(vfio_group_list);
@@ -190,6 +191,16 @@ void vfio_region_write(void *opaque, hwaddr addr,
         uint64_t qword;
     } buf;
 
+    trace_vfio_region_write(vbasedev->name, region->nr, addr, data, size);
+    if (!(region->flags & VFIO_REGION_INFO_FLAG_WRITE)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "Invalid write to read only vfio region (%s:region%d"
+                      "+0x%"HWADDR_PRIx" size %d)\n", vbasedev->name,
+                      region->nr, addr, size);
+
+        return;
+    }
+
     switch (size) {
     case 1:
         buf.byte = data;
@@ -215,8 +226,6 @@ void vfio_region_write(void *opaque, hwaddr addr,
                      addr, data, size);
     }
 
-    trace_vfio_region_write(vbasedev->name, region->nr, addr, data, size);
-
     /*
      * A read or write to a BAR always signals an INTx EOI.  This will
      * do nothing if not pending (including not in INTx mode).  We assume
-- 
2.17.1