[PATCH v2 1/1] xen/arm: map_domain_page: reuse slots with avail == 0

[PATCH v2 1/1] xen/arm: map_domain_page: reuse slots with avail == 0

[Stefano Stabellini]

If a slot has avail == 0 but still points to the right mfn, reuse it.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>


Changes in v2:
- check that the slot which we are about to reuse is valid.
---
 xen/arch/arm/mm.c |   17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 44ec0e3..21e20fa 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -232,7 +232,15 @@ void *map_domain_page(unsigned long mfn)
           i < DOMHEAP_ENTRIES;
           slot = (slot + 1) % DOMHEAP_ENTRIES, i++ )
     {
-        if ( map[slot].pt.avail == 0 )
+        if ( map[slot].pt.avail < 0xf &&
+             map[slot].pt.base == slot_mfn &&
+             map[slot].pt.valid )
+        {
+            /* This slot already points to the right place; reuse it */
+            map[slot].pt.avail++;
+            break;
+        }
+        else if ( map[slot].pt.avail == 0 )
         {
             /* Commandeer this 2MB slot */
             pte = mfn_to_xen_entry(slot_mfn);
@@ -240,12 +248,7 @@ void *map_domain_page(unsigned long mfn)
             write_pte(map + slot, pte);
             break;
         }
-        else if ( map[slot].pt.avail < 0xf && map[slot].pt.base == slot_mfn )
-        {
-            /* This slot already points to the right place; reuse it */
-            map[slot].pt.avail++;
-            break;
-        }
+
     }
     /* If the map fills up, the callers have misbehaved. */
     BUG_ON(i == DOMHEAP_ENTRIES);
-- 
1.7.2.5

Re: [PATCH v2 1/1] xen/arm: map_domain_page: reuse slots with avail == 0

[Tim Deegan]

At 13:06 +0100 on 30 Sep (1380546372), Stefano Stabellini wrote:
> If a slot has avail == 0 but still points to the right mfn, reuse it.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

Acked-by: Tim Deegan <tim@xen.org>

> Changes in v2:
> - check that the slot which we are about to reuse is valid.
> ---
>  xen/arch/arm/mm.c |   17 ++++++++++-------
>  1 files changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 44ec0e3..21e20fa 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -232,7 +232,15 @@ void *map_domain_page(unsigned long mfn)
>            i < DOMHEAP_ENTRIES;
>            slot = (slot + 1) % DOMHEAP_ENTRIES, i++ )
>      {
> -        if ( map[slot].pt.avail == 0 )
> +        if ( map[slot].pt.avail < 0xf &&
> +             map[slot].pt.base == slot_mfn &&
> +             map[slot].pt.valid )
> +        {
> +            /* This slot already points to the right place; reuse it */
> +            map[slot].pt.avail++;
> +            break;
> +        }
> +        else if ( map[slot].pt.avail == 0 )
>          {
>              /* Commandeer this 2MB slot */
>              pte = mfn_to_xen_entry(slot_mfn);
> @@ -240,12 +248,7 @@ void *map_domain_page(unsigned long mfn)
>              write_pte(map + slot, pte);
>              break;
>          }
> -        else if ( map[slot].pt.avail < 0xf && map[slot].pt.base == slot_mfn )
> -        {
> -            /* This slot already points to the right place; reuse it */
> -            map[slot].pt.avail++;
> -            break;
> -        }
> +
>      }
>      /* If the map fills up, the callers have misbehaved. */
>      BUG_ON(i == DOMHEAP_ENTRIES);
> -- 
> 1.7.2.5
> 

Re: [PATCH v2 1/1] xen/arm: map_domain_page: reuse slots with avail == 0

[Ian Campbell]

On Mon, 2013-09-30 at 13:17 +0100, Tim Deegan wrote:
> At 13:06 +0100 on 30 Sep (1380546372), Stefano Stabellini wrote:
> > If a slot has avail == 0 but still points to the right mfn, reuse it.
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> 
> Acked-by: Tim Deegan <tim@xen.org>

Likewise, and applied.