[PATCH] hw/vfio: let readonly flag take effect for mmaped regions

[yan . y . zhao]

From: Yan Zhao <address@hidden>

currently, vfio regions without VFIO_REGION_INFO_FLAG_WRITE are only
read-only when VFIO_REGION_INFO_FLAG_MMAP is not set.

regions with flag VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_MMAP
are only read-only in host page table for qemu.

This patch sets corresponding ept page entries read-only for regions
with flag VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_MMAP.

accordingly, it ignores guest write when guest writes to the read-only
regions are trapped.

Signed-off-by: Yan Zhao <address@hidden>
Signed-off-by: Xin Zeng <address@hidden>
---
 hw/vfio/common.c | 4 ++++
 memory.c         | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 0b3593b3c0..e901621ca0 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -971,6 +971,10 @@ int vfio_region_mmap(VFIORegion *region)
                                           name, region->mmaps[i].size,
                                           region->mmaps[i].mmap);
         g_free(name);
+
+        if (!(region->flags & VFIO_REGION_INFO_FLAG_WRITE)) {
+            memory_region_set_readonly(&region->mmaps[i].mem, true);
+        }
         memory_region_add_subregion(region->mem, region->mmaps[i].offset,
                                     &region->mmaps[i].mem);
 
diff --git a/memory.c b/memory.c
index 601b749906..4b1071dc74 100644
--- a/memory.c
+++ b/memory.c
@@ -1313,6 +1313,9 @@ static void memory_region_ram_device_write(void *opaque, 
hwaddr addr,
     MemoryRegion *mr = opaque;
 
     trace_memory_region_ram_device_write(get_cpu_index(), mr, addr, data, 
size);
+    if (mr->readonly) {
+        return;
+    }
 
     switch (size) {
     case 1:
-- 
2.17.1