Re: [Qemu-devel] [PATCH v2 03/15] pc-dimm: keep the state of the whole backend memory

[Stefan Hajnoczi]

On Fri, May 20, 2016 at 04:20:00PM +0800, Xiao Guangrong wrote:
> QEMU keeps the state of memory of dimm device during live migration,
> however, it is not enough for nvdimm device as its memory does not
> contain its label data, so that we should protect the whole backend
> memory instead
> 
> Signed-off-by: Xiao Guangrong <address@hidden>
> ---
>  hw/mem/pc-dimm.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
> index 6de2275..72b33ba 100644
> --- a/hw/mem/pc-dimm.c
> +++ b/hw/mem/pc-dimm.c
> @@ -105,9 +105,16 @@ void pc_dimm_memory_plug(DeviceState *dev, 
> MemoryHotplugState *hpms,
>      }
>  
>      memory_region_add_subregion(&hpms->mr, addr - hpms->base, mr);
> -    vmstate_register_ram(mr, dev);
>      numa_set_mem_node_id(addr, memory_region_size(mr), dimm->node);
>  
> +    /*
> +     * save the state only for @mr is not enough as it does not contain
> +     * the label data of NVDIMM device, so that we keep the state of
> +     * whole hostmem instead.
> +     */
> +    vmstate_register_ram(host_memory_backend_get_memory(dimm->hostmem, errp),
> +                         dev);
> +
>  out:
>      error_propagate(errp, local_err);
>  }

In Patch 1 you introduced a callback to get the guest-visible memory
region.  Instead of mentioning NVDIMM in generic pc-dimm.c code, it
would be cleaner to add another callback to get the vmstate memory
region:

  .get_guest_memory_region() - Patch 1
  .get_vmstate_memory_region() - a new patch in this series

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