memory: Replace skip_dump flag with "ram_device"

Setting skip_dump on a MemoryRegion allows us to modify one specific
code path, but the restriction we're trying to address encompasses
more than that.  If we have a RAM MemoryRegion backed by a physical
device, it not only restricts our ability to dump that region, but
also affects how we should manipulate it.  Here we recognize that
MemoryRegions do not change to sometimes allow dumps and other times
not, so we replace setting the skip_dump flag with a new initializer
so that we know exactly the type of region to which we're applying
this behavior.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>

5 files changed, 43 insertions, 24 deletions

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 9505fb3040..c764cb3d22 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -724,12 +724,11 @@ int vfio_region_mmap(VFIORegion *region)
 
         name = g_strdup_printf("%s mmaps[%d]",
                                memory_region_name(region->mem), i);
-        memory_region_init_ram_ptr(&region->mmaps[i].mem,
-                                   memory_region_owner(region->mem),
-                                   name, region->mmaps[i].size,
-                                   region->mmaps[i].mmap);
+        memory_region_init_ram_device_ptr(&region->mmaps[i].mem,
+                                          memory_region_owner(region->mem),
+                                          name, region->mmaps[i].size,
+                                          region->mmaps[i].mmap);
         g_free(name);
-        memory_region_set_skip_dump(&region->mmaps[i].mem);
         memory_region_add_subregion(region->mem, region->mmaps[i].offset,
                                     &region->mmaps[i].mem);
 
diff --git a/hw/vfio/spapr.c b/hw/vfio/spapr.c
index 7443d348d9..4409bcc0d7 100644
--- a/hw/vfio/spapr.c
+++ b/hw/vfio/spapr.c
@@ -25,7 +25,7 @@ static bool vfio_prereg_listener_skipped_section(MemoryRegionSection *section)
     }
 
     return !memory_region_is_ram(section->mr) ||
-            memory_region_is_skip_dump(section->mr);
+            memory_region_is_ram_device(section->mr);
 }
 
 static void *vfio_prereg_gpa_to_vaddr(MemoryRegionSection *section, hwaddr gpa)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 79ccaaba1f..a75b8c3465 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -209,7 +209,7 @@ struct MemoryRegion {
     void (*destructor)(MemoryRegion *mr);
     uint64_t align;
     bool terminates;
-    bool skip_dump;
+    bool ram_device;
     bool enabled;
     bool warning_printed; /* For reservations */
     uint8_t vga_logging_count;
@@ -449,6 +449,30 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
                                 void *ptr);
 
 /**
+ * memory_region_init_ram_device_ptr:  Initialize RAM device memory region from
+ *                                     a user-provided pointer.
+ *
+ * A RAM device represents a mapping to a physical device, such as to a PCI
+ * MMIO BAR of an vfio-pci assigned device.  The memory region may be mapped
+ * into the VM address space and access to the region will modify memory
+ * directly.  However, the memory region should not be included in a memory
+ * dump (device may not be enabled/mapped at the time of the dump), and
+ * operations incompatible with manipulating MMIO should be avoided.  Replaces
+ * skip_dump flag.
+ *
+ * @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_ram_device_ptr(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.
  *
@@ -574,22 +598,13 @@ static inline bool memory_region_is_ram(MemoryRegion *mr)
 }
 
 /**
- * memory_region_is_skip_dump: check whether a memory region should not be
- *                             dumped
- *
- * Returns %true is a memory region should not be dumped(e.g. VFIO BAR MMAP).
+ * memory_region_is_ram_device: check whether a memory region is a ram device
  *
- * @mr: the memory region being queried
- */
-bool memory_region_is_skip_dump(MemoryRegion *mr);
-
-/**
- * memory_region_set_skip_dump: Set skip_dump flag, dump will ignore this memory
- *                              region
+ * Returns %true is a memory region is a device backed ram region
  *
  * @mr: the memory region being queried
  */
-void memory_region_set_skip_dump(MemoryRegion *mr);
+bool memory_region_is_ram_device(MemoryRegion *mr);
 
 /**
  * memory_region_is_romd: check whether a memory region is in ROMD mode
diff --git a/memory.c b/memory.c
index edbc7012b6..7ffcff1d34 100644
--- a/memory.c
+++ b/memory.c
@@ -1355,9 +1355,14 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
     mr->ram_block = qemu_ram_alloc_from_ptr(size, ptr, mr, &error_fatal);
 }
 
-void memory_region_set_skip_dump(MemoryRegion *mr)
+void memory_region_init_ram_device_ptr(MemoryRegion *mr,
+                                       Object *owner,
+                                       const char *name,
+                                       uint64_t size,
+                                       void *ptr)
 {
-    mr->skip_dump = true;
+    memory_region_init_ram_ptr(mr, owner, name, size, ptr);
+    mr->ram_device = true;
 }
 
 void memory_region_init_alias(MemoryRegion *mr,
@@ -1491,9 +1496,9 @@ const char *memory_region_name(const MemoryRegion *mr)
     return mr->name;
 }
 
-bool memory_region_is_skip_dump(MemoryRegion *mr)
+bool memory_region_is_ram_device(MemoryRegion *mr)
 {
-    return mr->skip_dump;
+    return mr->ram_device;
 }
 
 uint8_t memory_region_get_dirty_log_mask(MemoryRegion *mr)
diff --git a/memory_mapping.c b/memory_mapping.c
index e3e0d95172..6a39d71da2 100644
--- a/memory_mapping.c
+++ b/memory_mapping.c
@@ -206,7 +206,7 @@ static void guest_phys_blocks_region_add(MemoryListener *listener,
 
     /* we only care about RAM */
     if (!memory_region_is_ram(section->mr) ||
-        memory_region_is_skip_dump(section->mr)) {
+        memory_region_is_ram_device(section->mr)) {
         return;
     }