[Qemu-devel] [PATCH] Skip vfio mmap bar regions during memory dump

[Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>]

The PCI MMIO might be disabled or the device in the reset state.
Make sure we do not dump these memory regions.

Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
---
 hw/misc/vfio.c        |  2 +-
 include/exec/memory.h | 27 +++++++++++++++++++++++++++
 memory.c              | 16 ++++++++++++++++
 memory_mapping.c      |  3 ++-
 4 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index d69bb29..fd6dbe9 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -2721,7 +2721,7 @@ static int vfio_mmap_bar(VFIODevice *vdev, VFIOBAR *bar,
             goto empty_region;
         }
 
-        memory_region_init_ram_ptr(submem, OBJECT(vdev), name, size, *map);
+        memory_region_init_vfio_mmap(submem, OBJECT(vdev), name, size, *map);
     } else {
 empty_region:
         /* Create a zero sized sub-region to make cleanup easy. */
diff --git a/include/exec/memory.h b/include/exec/memory.h
index fc6e93d..e184df6 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -144,6 +144,7 @@ struct MemoryRegion {
     bool terminates;
     bool romd_mode;
     bool ram;
+    bool vfio_mmap;
     bool readonly; /* For RAM regions */
     bool enabled;
     bool rom_device;
@@ -329,6 +330,23 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
                                 void *ptr);
 
 /**
+ * memory_region_init_vfio_mmap:  Initialize VFIO mmap memory region from a
+ *                                user-provided pointer.  Accesses into the
+ *                                region will modify memory directly.
+ *
+ * @mr: the #MemoryRegion to be initialized.
+ * @owner: the object that tracks the region's reference count
+ * @name: the name of the region.
+ * @size: size of the region.
+ * @ptr: memory to be mapped; must contain at least @size bytes.
+ */
+void memory_region_init_vfio_mmap(MemoryRegion *mr,
+                                  struct Object *owner,
+                                  const char *name,
+                                  uint64_t size,
+                                  void *ptr);
+
+/**
  * memory_region_init_alias: Initialize a memory region that aliases all or a
  *                           part of another memory region.
  *
@@ -434,6 +452,15 @@ uint64_t memory_region_size(MemoryRegion *mr);
 bool memory_region_is_ram(MemoryRegion *mr);
 
 /**
+ * memory_region_is_vfio_mmap: check whether a memory region is VFIO mmap
+ *
+ * Returns %true is a memory region is VFIO.
+ *
+ * @mr: the memory region being queried
+ */
+bool memory_region_is_vfio_mmap(MemoryRegion *mr);
+
+/**
  * memory_region_is_romd: check whether a memory region is in ROMD mode
  *
  * Returns %true if a memory region is a ROM device and currently set to allow
diff --git a/memory.c b/memory.c
index 664d3e6..63eadaa 100644
--- a/memory.c
+++ b/memory.c
@@ -847,6 +847,7 @@ void memory_region_init(MemoryRegion *mr,
     mr->enabled = true;
     mr->terminates = false;
     mr->ram = false;
+    mr->vfio_mmap = false;
     mr->romd_mode = true;
     mr->readonly = false;
     mr->rom_device = false;
@@ -1032,6 +1033,16 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
     mr->ram_addr = qemu_ram_alloc_from_ptr(size, ptr, mr);
 }
 
+void memory_region_init_vfio_mmap(MemoryRegion *mr,
+                                  Object *owner,
+                                  const char *name,
+                                  uint64_t size,
+                                  void *ptr)
+{
+    memory_region_init_ram_ptr(mr, owner, name, size, ptr);
+    mr->vfio_mmap = true;
+}
+
 void memory_region_init_alias(MemoryRegion *mr,
                               Object *owner,
                               const char *name,
@@ -1129,6 +1140,11 @@ bool memory_region_is_ram(MemoryRegion *mr)
     return mr->ram;
 }
 
+bool memory_region_is_vfio_mmap(MemoryRegion *mr)
+{
+    return mr->vfio_mmap;
+}
+
 bool memory_region_is_logging(MemoryRegion *mr)
 {
     return mr->dirty_log_mask;
diff --git a/memory_mapping.c b/memory_mapping.c
index 87a6ed5..64ef46d 100644
--- a/memory_mapping.c
+++ b/memory_mapping.c
@@ -203,7 +203,8 @@ static void guest_phys_blocks_region_add(MemoryListener *listener,
     GuestPhysBlock *predecessor;
 
     /* we only care about RAM */
-    if (!memory_region_is_ram(section->mr)) {
+    if (!memory_region_is_ram(section->mr) ||
+        memory_region_is_vfio_mmap(section->mr)) {
         return;
     }
 
-- 
1.8.3.1