[PATCH] pci: make ROM memory resizable

[Vladimir Sementsov-Ogievskiy]

On migration, on target we load local ROM file. But actual ROM content
migrates through migration channel. Original ROM content from local
file doesn't matter. But when size mismatch - we have an error like

 Size mismatch: 0000:00:03.0/virtio-net-pci.rom: 0x40000 != 0x80000: Invalid 
argument

Let's just allow resizing of ROM memory. This way migration is not
relate on local ROM file on target node which is loaded by default but
is not actually needed.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
 hw/pci/pci.c          |  7 +++++--
 include/exec/memory.h | 26 ++++++++++++++++++++++++++
 softmmu/memory.c      | 39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index def5000e7b..72ee8f6aea 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -59,6 +59,8 @@
 # define PCI_DPRINTF(format, ...)       do { } while (0)
 #endif
 
+#define MAX_ROM_SIZE (2 * GiB)
+
 bool pci_available = true;
 
 static char *pcibus_get_dev_path(DeviceState *dev);
@@ -2341,7 +2343,7 @@ static void pci_add_option_rom(PCIDevice *pdev, bool 
is_default_rom,
         error_setg(errp, "romfile \"%s\" is empty", pdev->romfile);
         g_free(path);
         return;
-    } else if (size > 2 * GiB) {
+    } else if (size > MAX_ROM_SIZE) {
         error_setg(errp, "romfile \"%s\" too large (size cannot exceed 2 GiB)",
                    pdev->romfile);
         g_free(path);
@@ -2366,7 +2368,8 @@ static void pci_add_option_rom(PCIDevice *pdev, bool 
is_default_rom,
         snprintf(name, sizeof(name), "%s.rom", 
object_get_typename(OBJECT(pdev)));
     }
     pdev->has_rom = true;
-    memory_region_init_rom(&pdev->rom, OBJECT(pdev), name, pdev->romsize, 
&error_fatal);
+    memory_region_init_rom_resizable(&pdev->rom, OBJECT(pdev), name,
+                                     pdev->romsize, MAX_ROM_SIZE, 
&error_fatal);
     ptr = memory_region_get_ram_ptr(&pdev->rom);
     if (load_image_size(path, ptr, size) < 0) {
         error_setg(errp, "failed to load romfile \"%s\"", pdev->romfile);
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 15ade918ba..ed1e5d9126 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1453,6 +1453,19 @@ void memory_region_init_rom_nomigrate(MemoryRegion *mr,
                                       uint64_t size,
                                       Error **errp);
 
+/*
+ * memory_region_init_rom_nomigrate_resizable: same as
+ * memory_region_init_rom_nomigrate(), but initialize resizable memory region.
+ *
+ * @max_size maximum allowed size.
+ */
+void memory_region_init_rom_nomigrate_resizable(MemoryRegion *mr,
+                                                struct Object *owner,
+                                                const char *name,
+                                                uint64_t size,
+                                                uint64_t max_size,
+                                                Error **errp);
+
 /**
  * memory_region_init_rom_device_nomigrate:  Initialize a ROM memory region.
  *                                 Writes are handled via callbacks.
@@ -1562,6 +1575,19 @@ void memory_region_init_rom(MemoryRegion *mr,
                             uint64_t size,
                             Error **errp);
 
+/*
+ * memory_region_init_rom_resizable: same as memory_region_init_rom(),
+ * but initialize resizable memory region.
+ *
+ * @max_size maximum allowed size.
+ */
+void memory_region_init_rom_resizable(MemoryRegion *mr,
+                                      struct Object *owner,
+                                      const char *name,
+                                      uint64_t size,
+                                      uint64_t max_size,
+                                      Error **errp);
+
 /**
  * memory_region_init_rom_device:  Initialize a ROM memory region.
  *                                 Writes are handled via callbacks.
diff --git a/softmmu/memory.c b/softmmu/memory.c
index b1a6cae6f5..744d03bc02 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -1701,6 +1701,18 @@ void memory_region_init_rom_nomigrate(MemoryRegion *mr,
     mr->readonly = true;
 }
 
+void memory_region_init_rom_nomigrate_resizable(MemoryRegion *mr,
+                                                struct Object *owner,
+                                                const char *name,
+                                                uint64_t size,
+                                                uint64_t max_size,
+                                                Error **errp)
+{
+    memory_region_init_resizeable_ram(mr, owner, name, size, max_size, NULL,
+                                      errp);
+    mr->readonly = true;
+}
+
 void memory_region_init_rom_device_nomigrate(MemoryRegion *mr,
                                              Object *owner,
                                              const MemoryRegionOps *ops,
@@ -3580,6 +3592,33 @@ void memory_region_init_rom(MemoryRegion *mr,
     vmstate_register_ram(mr, owner_dev);
 }
 
+void memory_region_init_rom_resizable(MemoryRegion *mr,
+                                      struct Object *owner,
+                                      const char *name,
+                                      uint64_t size,
+                                      uint64_t max_size,
+                                      Error **errp)
+{
+    DeviceState *owner_dev;
+    Error *err = NULL;
+
+    memory_region_init_rom_nomigrate_resizable(mr, owner, name, size, max_size,
+                                               &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }
+    /*
+     * This will assert if owner is neither NULL nor a DeviceState.
+     * We only want the owner here for the purposes of defining a
+     * unique name for migration. TODO: Ideally we should implement
+     * a naming scheme for Objects which are not DeviceStates, in
+     * which case we can relax this restriction.
+     */
+    owner_dev = DEVICE(owner);
+    vmstate_register_ram(mr, owner_dev);
+}
+
 void memory_region_init_rom_device(MemoryRegion *mr,
                                    Object *owner,
                                    const MemoryRegionOps *ops,
-- 
2.34.1