Re: [Xen-devel] [RFC QEMU PATCH v4 03/10] hostmem-xen: add a host memory backend for Xen

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Thu, Dec 07, 2017 at 06:18:05PM +0800, Haozhong Zhang wrote:
> diff --git a/backends/hostmem.c b/backends/hostmem.c
> index ee2c2d5bfd..ba13a52994 100644
> --- a/backends/hostmem.c
> +++ b/backends/hostmem.c
> @@ -12,6 +12,7 @@
>  #include "qemu/osdep.h"
>  #include "sysemu/hostmem.h"
>  #include "hw/boards.h"
> +#include "hw/xen/xen.h"
>  #include "qapi/error.h"
>  #include "qapi/visitor.h"
>  #include "qapi-types.h"
> @@ -277,6 +278,14 @@ host_memory_backend_memory_complete(UserCreatable *uc, 
> Error **errp)
>              goto out;
>          }
>  
> +        /*
> +         * The backend storage of MEMORY_BACKEND_XEN is managed by Xen,
> +         * so no further work in this function is needed.
> +         */
> +        if (xen_enabled() && !backend->mr.ram_block) {
> +            goto out;
> +        }
> +
>          ptr = memory_region_get_ram_ptr(&backend->mr);
>          sz = memory_region_size(&backend->mr);
>  
> diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
> index 66eace5a5c..dcbfce33d5 100644
> --- a/hw/mem/pc-dimm.c
> +++ b/hw/mem/pc-dimm.c
> @@ -28,6 +28,7 @@
>  #include "sysemu/kvm.h"
>  #include "trace.h"
>  #include "hw/virtio/vhost.h"
> +#include "hw/xen/xen.h"
>  
>  typedef struct pc_dimms_capacity {
>       uint64_t size;
> @@ -108,7 +109,10 @@ void pc_dimm_memory_plug(DeviceState *dev, 
> MemoryHotplugState *hpms,
>      }
>  
>      memory_region_add_subregion(&hpms->mr, addr - hpms->base, mr);
> -    vmstate_register_ram(vmstate_mr, dev);
> +    /* memory-backend-xen is not backed by RAM. */
> +    if (!xen_enabled()) {

Is it possible to have the same condition as the one used in
host_memory_backend_memory_complete? i.e. base on whether the memory
region is mapped or not (backend->mr.ram_block).

> +        vmstate_register_ram(vmstate_mr, dev);
> +    }
>      numa_set_mem_node_id(addr, memory_region_size(mr), dimm->node);
>  
>  out:
> -- 
> 2.15.1
> 

-- 
Anthony PERARD

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