Re: [Xen-devel] [PATCH 2/2] libxc: fix PV vNUMA guest memory allocation

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 06/07/15 14:17, Wei Liu wrote:
> In 415b58c1 (tools/libxc: Batch memory allocations for PV guests) the
> number of super pages is calculated with the number of total pages. That
> is wrong. It breaks PV guest vNUMA. The correct number of super pages
> should be derived from the number of pages within that virtual NUMA
> node.
>
> Also change the name and type of super page variable to match the naming
> convention and type of normal page variable. Make the necessary
> adjustment to make code compile.
>
> Reported-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
> Cc: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> ---
>  tools/libxc/xc_dom_x86.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
> index acd7b3f..faabe96 100644
> --- a/tools/libxc/xc_dom_x86.c
> +++ b/tools/libxc/xc_dom_x86.c
> @@ -879,9 +879,8 @@ int arch_setup_meminit(struct xc_dom_image *dom)
>          for ( i = 0; i < nr_vmemranges; i++ )
>          {
>              unsigned int memflags;
> -            uint64_t pages;
> +            uint64_t pages, super_pages;
>              unsigned int pnode = vnode_to_pnode[vmemranges[i].nid];
> -            int nr_spages = dom->total_pages >> SUPERPAGE_PFN_SHIFT;
>              xen_pfn_t extents[SUPERPAGE_BATCH_SIZE];
>              xen_pfn_t pfn_base_idx;
>  
> @@ -891,15 +890,16 @@ int arch_setup_meminit(struct xc_dom_image *dom)
>  
>              pages = (vmemranges[i].end - vmemranges[i].start)
>                  >> PAGE_SHIFT;
> +            super_pages = pages >> SUPERPAGE_PFN_SHIFT;
>              pfn_base = vmemranges[i].start >> PAGE_SHIFT;
>  
>              for ( pfn = pfn_base; pfn < pfn_base+pages; pfn++ )
>                  dom->p2m_host[pfn] = pfn;
>  
>              pfn_base_idx = pfn_base;
> -            while (nr_spages) {
> -                int count = min(nr_spages, SUPERPAGE_BATCH_SIZE);
> -                nr_spages -= count;
> +            while (super_pages) {
> +                int count = min_t(uint64_t, super_pages, 
> SUPERPAGE_BATCH_SIZE);

This line alone indicates that int is not an appropriate type for
count.  unsigned int as as an absolute minimum, as it will be bounded to
SUPERPAGE_BATCH_SIZE.

~Andrew

> +                super_pages -= count;
>  
>                  for ( pfn = pfn_base_idx, j = 0;
>                        pfn < pfn_base_idx + (count << SUPERPAGE_PFN_SHIFT);


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