Re: [Xen-devel] [PATCH 1/5] x86/traps: Drop paging_mode_external() handling from the PV pagefault path

[Tim Deegan <tim@xxxxxxx>]

At 10:43 +0000 on 12 Dec (1481539421), Andrew Cooper wrote:
> PV guests necessarily can't be external, as Xen must steal address space from
> them.  Pagefaults for HVM guests are handled by {vmx,svm}_vmexit_handler() and
> don't enter the PV fixup_page_fault() path.
> 
> This paging_fault() callsite is therefore dead code, so drop it.
> 
> Clarify the comment at the other paging_fault() callsite to indicate that it
> covers the logdirty case only.
> 
> No functional change.

IMO this is a change, just not on any supported config.

> -    /* For non-external shadowed guests, we fix up both their own 
> -     * pagefaults and Xen's, since they share the pagetables. */
> +    /*
> +     * For non-external shadowed guests (i.e. PV guests with logdirty
> +     * active), we fix up both their own pagefaults and Xen's, since
> +     * they share the pagetables.
> +     */
>      if ( paging_mode_enabled(d) && !paging_mode_external(d) )

Here we can drop the check of !paging_mode_external(d), or maybe turn
it into an assertion somewhere.

With that,

Acked-by: Tim Deegan <tim@xxxxxxx>

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