On Fri, Apr 23, 2021 at 12:52:57PM +0200, Jan Beulich wrote:
> --- a/xen/arch/x86/mm/shadow/set.c
> +++ b/xen/arch/x86/mm/shadow/set.c
> @@ -94,6 +94,15 @@ shadow_get_page_from_l1e(shadow_l1e_t sl
> ASSERT(!sh_l1e_is_magic(sl1e));
> ASSERT(shadow_mode_refcounts(d));
>
> + /*
> + * Check whether refcounting is suppressed on this page. For example,
> + * VMX'es APIC access MFN is just a surrogate page. It doesn't actually
> + * get accessed, and hence there's no need to refcount it.
> + */
> + mfn = shadow_l1e_get_mfn(sl1e);
> + if ( mfn_valid(mfn) && page_refcounting_suppressed(mfn_to_page(mfn)) )
> + return 0;
> +
> res = get_page_from_l1e(sl1e, d, d);
>
> /*
> --- a/xen/arch/x86/mm/shadow/types.h
> +++ b/xen/arch/x86/mm/shadow/types.h
> @@ -276,9 +276,16 @@ int shadow_set_l4e(struct domain *d, sha
> static void inline
> shadow_put_page_from_l1e(shadow_l1e_t sl1e, struct domain *d)
> {
> + mfn_t mfn;
> +
> if ( !shadow_mode_refcounts(d) )
> return;
>
> + if ( mfn_valid(mfn = shadow_l1e_get_mfn(sl1e)) &&
Nit: I would prefer if assigned mfn outside of the condition, like
it's done in the chunk added to shadow_get_page_from_l1e. The rest
LGTM, so:
Reviewed-by: Roger Pau Monné <roger....@citrix.com>
Thanks, Roger.
