On 02.11.2015 16:08, Xiao Guangrong wrote:

On 11/02/2015 08:19 PM, Vladimir Sementsov-Ogievskiy wrote:
On 02.11.2015 12:13, Xiao Guangrong wrote:
Curretly, the memory region of backed memory is directly mapped to
guest's address space, however, it is not true for nvdimm device

This patch let dimm device realize this fact and use
DIMMDeviceClass->get_memory_region method to get the mapped memory

Current code did not check the return value of get_memory_region as it
assumed the backend memory of pc-dimm is always properly initialized,
we make get_memory_region internally catch the case if something is

but here you call not pc-dimm's get_memory_region, but common ddc->get_memory_region, which may be nvdimm or possibly other future dimm, so, why not check it here? And than pc_dimm_get_memory_region may be left untouched (error_abort is ok, because errp is unused).

Signed-off-by: Xiao Guangrong <guangrong.x...@linux.intel.com>
  hw/mem/dimm.c    |  3 ++-
  hw/mem/pc-dimm.c | 12 +++++++++++-
  2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/hw/mem/dimm.c b/hw/mem/dimm.c
index 4a63409..498d380 100644
--- a/hw/mem/dimm.c
+++ b/hw/mem/dimm.c
@@ -377,8 +377,9 @@ static void dimm_get_size(Object *obj, Visitor *v, void *opaque,
      int64_t value;
      MemoryRegion *mr;
      DIMMDevice *dimm = DIMM(obj);
+    DIMMDeviceClass *ddc = DIMM_GET_CLASS(obj);
-    mr = host_memory_backend_get_memory(dimm->hostmem, errp);
+    mr = ddc->get_memory_region(dimm);
      value = memory_region_size(mr);
      visit_type_int(v, &value, name, errp);
diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
index 38323e9..e6b6a9f 100644
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -22,7 +22,17 @@
  static MemoryRegion *pc_dimm_get_memory_region(DIMMDevice *dimm)
- return host_memory_backend_get_memory(dimm->hostmem, &error_abort);
+    Error *local_err = NULL;
+    MemoryRegion *mr;
+    mr = host_memory_backend_get_memory(dimm->hostmem, &local_err);
+    /*
+     * plug a pc-dimm device whose backend memory was not properly
+     * initialized?
+     */
+    assert(!local_err && mr);
+    return mr;

this should squashed into previous patch, I think

You mean merger this patch with 19/35 (dimm: abstract dimm device from pc-dimm)? The 19/35 mostly ‘moves’ the things, this one changes the core logic, it is not
a big deal. :D

stupid me, you are right)

  static void pc_dimm_class_init(ObjectClass *oc, void *data)

I've discovered suddenly, that

MemoryRegion *
host_memory_backend_get_memory(HostMemoryBackend *backend, Error **errp)
     return memory_region_size(&backend->mr) ? &backend->mr : NULL;

- it doesn't use errp at all. In my opinion, this should be fixed globally, by deleting useless parameter in separate patch. Or just squash your function into previous patch.

Yup, this is a globally interface so i prefer to make a separate patch to do the
cleanup after this patchset.

Best regards,
* now, @virtuozzo.com instead of @parallels.com. Sorry for this inconvenience.

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