Re: [PATCH v3 01/18] x86/PoD: map one page at a time in p2m_pod_zero_check()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 07/10/2026 11:40 am, George Dunlap wrote:
> diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c
> index 4602c32cff..0b0beca15a 100644
> --- a/xen/arch/x86/mm/p2m-pod.c
> +++ b/xen/arch/x86/mm/p2m-pod.c
> @@ -911,7 +912,12 @@ p2m_pod_zero_check(struct p2m_domain *p2m, const gfn_t 
> *gfns, unsigned int count
>      if ( paging_mode_shadow(d) )
>          max_ref++;
>  
> -    /* First, get the gfn list, translate to mfns, and map the pages. */
> +    /*
> +     * First, get the gfn list, translate to mfns, and pick the pages to
> +     * check.  They are mapped one at a time below, as in
> +     * p2m_pod_zero_check_superpage(): a vCPU can hold only a few transient
> +     * mappings at once, and the p2m lookups and updates here need some too.
> +     */

Actually, I think this wants almost entirely dropping.   Yes, "and maps
the pages." needs editing, and should probably say "and check for being
a plausible candidate" or so, which was missing previously.

The rest is a justification of why we do mapping in the same way we do
it generally, and not useful to have in the source code.

~Andrew