Re: [PATCH v1 2/8] x86/xen: simplify xen_oldmem_pfn_is_ram()

[David Hildenbrand <david@redhat.com>]

On 29.09.21 10:45, David Hildenbrand wrote:
>>
>> How about
>>
>>       return a.mem_type != HVMMEM_mmio_dm;
>>
> 
> Ha, how could I have missed that :)
> 
>>
>> Result should be promoted to int and this has added benefit of not requiring changes in patch 4.
>>
> 
> Can we go one step further and do
> 
> 
> @@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
>           struct xen_hvm_get_mem_type a = {
>                   .domid = DOMID_SELF,
>                   .pfn = pfn,
> +               .mem_type = HVMMEM_ram_rw,
>           };
> -       int ram;
>    
> -       if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
> -               return -ENXIO;
> -
> -       switch (a.mem_type) {
> -       case HVMMEM_mmio_dm:
> -               ram = 0;
> -               break;
> -       case HVMMEM_ram_rw:
> -       case HVMMEM_ram_ro:
> -       default:
> -               ram = 1;
> -               break;
> -       }
> -
> -       return ram;
> +       HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a);
> +       return a.mem_type != HVMMEM_mmio_dm;
>    }
>    #endif
> 
> 
> Assuming that if HYPERVISOR_hvm_op() fails that
> .mem_type is not set to HVMMEM_mmio_dm.
> 

Okay we can't, due to "__must_check" ...

-- 
Thanks,

David / dhildenb