Re: [Xen-devel] [PATCH v3 3/4] libxc: rework vnuma bits in setup_guest

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 06/01/2015 06:19 AM, Wei Liu wrote:
> Make the setup process similar to PV counterpart. That is, to allocate a
> P2M array that covers the whole memory range and start from there. This
> is clearer than using an array with no holes in it.
>
> Also the dummy layout should take MMIO hole into consideration. We might
> end up having two vmemranges in the dummy layout.
>
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

with a couple of nits below that you might consider.


> @@ -325,16 +352,23 @@ static int setup_guest(xc_interface *xch,
>       DPRINTF("  TOTAL:    %016"PRIx64"->%016"PRIx64"\n", v_start, v_end);
>       DPRINTF("  ENTRY:    %016"PRIx64"\n", elf_uval(&elf, elf.ehdr, e_entry));
>   
> -    if ( (page_array = malloc(nr_pages * sizeof(xen_pfn_t))) == NULL )
> +    if ( (page_array = malloc(p2m_size * sizeof(xen_pfn_t))) == NULL )
>       {
>           PERROR("Could not allocate memory.");
>           goto error_out;
>       }
>   
> -    for ( i = 0; i < nr_pages; i++ )
> -        page_array[i] = i;
> -    for ( i = args->mmio_start >> PAGE_SHIFT; i < nr_pages; i++ )
> -        page_array[i] += args->mmio_size >> PAGE_SHIFT;
> +    for ( i = 0; i < p2m_size; i++ )
> +        page_array[i] = ((xen_pfn_t)-1);
For large guests memset-ting page_array to 0xf should be much faster 
(but obviously not type-safe).

> +    for ( vmemid = 0; vmemid < args->nr_vmemranges; vmemid++ )
> +    {
> +        uint64_t pfn;
> +
> +        for ( pfn = args->vmemranges[vmemid].start >> PAGE_SHIFT;
> +              pfn < args->vmemranges[vmemid].end >> PAGE_SHIFT;
> +              pfn++ )
> +            page_array[pfn] = pfn;
> +    }
>   
>       /*
>        * Try to claim pages for early warning of insufficient memory available.
> @@ -645,6 +679,12 @@ static int setup_guest(xc_interface *xch,
>    error_out:
>       rc = -1;
>    out:
> +    if ( use_dummy )
Or 'if (args->vmemranges == dummy_vmemrange)' and drop use_dummy variable.

-boris

> +    {
> +        args->nr_vnodes = 0;
> +        args->vmemranges = NULL;
> +        args->vnode_to_pnode = NULL;
> +    }
>       if ( elf_check_broken(&elf) )
>           ERROR("HVM ELF broken: %s", elf_check_broken(&elf));
>   

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