[Xen-devel] [PATCH 2/4] xen/evtchn: Reduce the size of the poll_mask where possible

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Use domain_max_vcpus(d) in preference to MAX_VIRT_CPUS when allocating the
poll mask.  This allows x86 HVM guests to have a poll mask of 128 bits rather
than 8k bits.

While changing this, use xzalloc_array() in preference to xmalloc_array() to
avoid needing the subsequent call to bitmap_zero().

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Tim Deegan <tim@xxxxxxx>
CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
---
 xen/common/event_channel.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index 7d6de54..1c15569 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -1269,13 +1269,13 @@ int evtchn_init(struct domain *d)
     evtchn_from_port(d, 0)->state = ECS_RESERVED;
 
 #if MAX_VIRT_CPUS > BITS_PER_LONG
-    d->poll_mask = xmalloc_array(unsigned long, BITS_TO_LONGS(MAX_VIRT_CPUS));
+    d->poll_mask = xzalloc_array(
+        unsigned long, BITS_TO_LONGS(domain_max_vcpus(d)));
     if ( !d->poll_mask )
     {
         free_evtchn_bucket(d, d->evtchn);
         return -ENOMEM;
     }
-    bitmap_zero(d->poll_mask, MAX_VIRT_CPUS);
 #endif
 
     return 0;
-- 
1.7.10.4


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