Re: [Qemu-devel] [PATCH v3 12/13] nvdimm: make get_memory_region() perform checks and initialization

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 15 Jun 2018 16:04:47 +0200
David Hildenbrand <david@redhat.com> wrote:

> We might get a call to get_memory_region() before the device has been
> realized. We should return a consistent value, as the return value
> will e.g. later on be used in the pre_plug handler.
> 
> To avoid duplicating too much code, factor the initialization and checks
> out into a helper function.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  hw/mem/nvdimm.c | 46 +++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 37 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
> index df7646488b..deba5719bc 100644
> --- a/hw/mem/nvdimm.c
> +++ b/hw/mem/nvdimm.c
> @@ -71,20 +71,24 @@ static void nvdimm_init(Object *obj)
>                          NULL, NULL);
>  }
>  
> -static MemoryRegion *nvdimm_get_memory_region(PCDIMMDevice *dimm, Error **errp)
> +static void nvdimm_prepare_memory_region(NVDIMMDevice *nvdimm, Error **errp)
>  {
> -    NVDIMMDevice *nvdimm = NVDIMM(dimm);
> +    PCDIMMDevice *dimm = PC_DIMM(nvdimm);
> +    uint64_t align, pmem_size, size;
> +    MemoryRegion *mr;
>  
> -    return nvdimm->nvdimm_mr;
> -}
> +    if (nvdimm->nvdimm_mr) {
> +        return;
> +    }
>  
> -static void nvdimm_realize(PCDIMMDevice *dimm, Error **errp)
> -{
> -    MemoryRegion *mr = host_memory_backend_get_memory(dimm->hostmem);
> -    NVDIMMDevice *nvdimm = NVDIMM(dimm);
> -    uint64_t align, pmem_size, size = memory_region_size(mr);
> +    if (!dimm->hostmem) {
> +        error_setg(errp, "'" PC_DIMM_MEMDEV_PROP "' property must be set");
> +        return;
> +    }
>  
> +    mr = host_memory_backend_get_memory(dimm->hostmem);
>      align = memory_region_get_alignment(mr);
> +    size = memory_region_size(mr);
>  
>      pmem_size = size - nvdimm->label_size;
>      nvdimm->label_data = memory_region_get_ram_ptr(mr) + pmem_size;
> @@ -108,6 +112,30 @@ static void nvdimm_realize(PCDIMMDevice *dimm, Error **errp)
>      nvdimm->nvdimm_mr->align = align;
>  }
>  
> +static MemoryRegion *nvdimm_get_memory_region(PCDIMMDevice *dimm, Error **errp)
> +{
> +    NVDIMMDevice *nvdimm = NVDIMM(dimm);
> +    Error *local_err = NULL;
> +
> +    if (!nvdimm->nvdimm_mr) {
> +        nvdimm_prepare_memory_region(nvdimm, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return NULL;
> +        }
> +    }
> +    return nvdimm->nvdimm_mr;
> +}
> +
> +static void nvdimm_realize(PCDIMMDevice *dimm, Error **errp)
> +{
> +    NVDIMMDevice *nvdimm = NVDIMM(dimm);
> +
> +    if (!nvdimm->nvdimm_mr) {
> +        nvdimm_prepare_memory_region(nvdimm, errp);
> +    }
> +}
> +
>  /*
>   * the caller should check the input parameters before calling
>   * label read/write functions.