The grant table code had some particularly frequent repetitions of
mfn_to_page() on each time the same input arguments. To help the
compiler (which can do only a limited job on CSE), this adds explicit
caching of the transformation result in a few places.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
--- 2009-09-10.orig/xen/common/grant_table.c 2009-09-10 15:27:52.000000000
+0200
+++ 2009-09-10/xen/common/grant_table.c 2009-09-10 17:19:24.000000000 +0200
@@ -198,6 +198,7 @@ __gnttab_map_grant_ref(
struct vcpu *led;
int handle;
unsigned long frame = 0, nr_gets = 0;
+ struct page_info *pg;
int rc = GNTST_okay;
u32 old_pin;
u32 act_pin;
@@ -346,12 +347,13 @@ __gnttab_map_grant_ref(
spin_unlock(&rd->grant_table->lock);
- if ( !mfn_valid(frame) ||
- (owner = page_get_owner_and_reference(mfn_to_page(frame))) == dom_io )
+ pg = mfn_valid(frame) ? mfn_to_page(frame) : NULL;
+
+ if ( !pg || (owner = page_get_owner_and_reference(pg)) == dom_io )
{
/* Only needed the reference to confirm dom_io ownership. */
- if ( mfn_valid(frame) )
- put_page(mfn_to_page(frame));
+ if ( pg )
+ put_page(pg);
if ( paging_mode_external(ld) )
{
@@ -377,7 +379,7 @@ __gnttab_map_grant_ref(
else if ( owner == rd )
{
if ( gnttab_host_mapping_get_page_type(op, ld, rd) &&
- !get_page_type(mfn_to_page(frame), PGT_writable_page) )
+ !get_page_type(pg, PGT_writable_page) )
goto could_not_pin;
nr_gets++;
@@ -390,9 +392,9 @@ __gnttab_map_grant_ref(
if ( op->flags & GNTMAP_device_map )
{
nr_gets++;
- (void)get_page(mfn_to_page(frame), rd);
+ (void)get_page(pg, rd);
if ( !(op->flags & GNTMAP_readonly) )
- get_page_type(mfn_to_page(frame), PGT_writable_page);
+ get_page_type(pg, PGT_writable_page);
}
}
}
@@ -403,7 +405,7 @@ __gnttab_map_grant_ref(
gdprintk(XENLOG_WARNING, "Could not pin grant frame %lx\n",
frame);
if ( owner != NULL )
- put_page(mfn_to_page(frame));
+ put_page(pg);
rc = GNTST_general_error;
goto undo_out;
}
@@ -442,14 +444,14 @@ __gnttab_map_grant_ref(
if ( nr_gets > 1 )
{
if ( !(op->flags & GNTMAP_readonly) )
- put_page_type(mfn_to_page(frame));
- put_page(mfn_to_page(frame));
+ put_page_type(pg);
+ put_page(pg);
}
if ( nr_gets > 0 )
{
if ( gnttab_host_mapping_get_page_type(op, ld, rd) )
- put_page_type(mfn_to_page(frame));
- put_page(mfn_to_page(frame));
+ put_page_type(pg);
+ put_page(pg);
}
spin_lock(&rd->grant_table->lock);
@@ -621,6 +623,7 @@ __gnttab_unmap_common_complete(struct gn
struct domain *ld, *rd;
struct active_grant_entry *act;
grant_entry_t *sha;
+ struct page_info *pg;
rd = op->rd;
@@ -651,14 +654,16 @@ __gnttab_unmap_common_complete(struct gn
goto unmap_out;
}
+ pg = mfn_to_page(op->frame);
+
if ( op->flags & GNTMAP_device_map )
{
if ( !is_iomem_page(act->frame) )
{
if ( op->flags & GNTMAP_readonly )
- put_page(mfn_to_page(op->frame));
+ put_page(pg);
else
- put_page_and_type(mfn_to_page(op->frame));
+ put_page_and_type(pg);
}
}
@@ -676,8 +681,8 @@ __gnttab_unmap_common_complete(struct gn
if ( !is_iomem_page(op->frame) )
{
if ( gnttab_host_mapping_get_page_type(op, ld, rd) )
- put_page_type(mfn_to_page(op->frame));
- put_page(mfn_to_page(op->frame));
+ put_page_type(pg);
+ put_page(pg);
}
}
@@ -1745,6 +1750,7 @@ gnttab_release_mappings(
struct domain *rd;
struct active_grant_entry *act;
struct grant_entry *sha;
+ struct page_info *pg;
BUG_ON(!d->is_dying);
@@ -1772,6 +1778,7 @@ gnttab_release_mappings(
act = &active_entry(rd->grant_table, ref);
sha = &shared_entry(rd->grant_table, ref);
+ pg = mfn_to_page(act->frame);
if ( map->flags & GNTMAP_readonly )
{
@@ -1780,7 +1787,7 @@ gnttab_release_mappings(
BUG_ON(!(act->pin & GNTPIN_devr_mask));
act->pin -= GNTPIN_devr_inc;
if ( !is_iomem_page(act->frame) )
- put_page(mfn_to_page(act->frame));
+ put_page(pg);
}
if ( map->flags & GNTMAP_host_map )
@@ -1789,7 +1796,7 @@ gnttab_release_mappings(
act->pin -= GNTPIN_hstr_inc;
if ( gnttab_release_host_mappings(d) &&
!is_iomem_page(act->frame) )
- put_page(mfn_to_page(act->frame));
+ put_page(pg);
}
}
else
@@ -1799,7 +1806,7 @@ gnttab_release_mappings(
BUG_ON(!(act->pin & GNTPIN_devw_mask));
act->pin -= GNTPIN_devw_inc;
if ( !is_iomem_page(act->frame) )
- put_page_and_type(mfn_to_page(act->frame));
+ put_page_and_type(pg);
}
if ( map->flags & GNTMAP_host_map )
@@ -1810,8 +1817,8 @@ gnttab_release_mappings(
!is_iomem_page(act->frame) )
{
if ( gnttab_host_mapping_get_page_type(map, d, rd) )
- put_page_type(mfn_to_page(act->frame));
- put_page(mfn_to_page(act->frame));
+ put_page_type(pg);
+ put_page(pg);
}
}
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