[Xen-changelog] [xen-unstable] passthrough: use domain pirq as index of struct hvm_irq_dpci's hvm_timer array

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxxxx>
# Date 1302005105 -3600
# Node ID fbfee2a01a917d1a02677c48e2935dafbadaa00a
# Parent  4fe0442aa5b7434ed10e63c027bbe9e9f6642dae
passthrough: use domain pirq as index of struct hvm_irq_dpci's hvm_timer array

Since d->nr_pirqs is guaranteed to be not larger than nr_irqs,
indexing arrays by the former ought to be preferred. In the case
given, the indices so far had to be computed specially in a number of
cases, whereas the indexes use now are all readily available.

This opens the possibility to fold the ->mirq[] and ->hvm_timer[]
members of struct hvm_irq_dpci into a single array, possibly with some
members overlayed in a union to reduce size (see
http://lists.xensource.com/archives/html/xen-devel/2011-03/msg02006.html).
Such space saving wouldn't, however, suffice to generally get the
respective allocation sizes here to below PAGE_SIZE, not even when
converting the array of structures into an array of pointers to
structures. Whether a multi-level lookup mechanism would make sense
here is questionable, as it can be expected that for other than Dom0
(which isn't hvm, and hence shouldn't use these data structures - see
http://lists.xensource.com/archives/html/xen-devel/2011-03/msg02004.html)
only very few entries would commonly be used here. An obvious
alternative would be to use rb or radix trees (both currently only
used in tmem).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---


diff -r 4fe0442aa5b7 -r fbfee2a01a91 xen/drivers/passthrough/io.c
--- a/xen/drivers/passthrough/io.c      Tue Apr 05 13:03:29 2011 +0100
+++ b/xen/drivers/passthrough/io.c      Tue Apr 05 13:05:05 2011 +0100
@@ -135,7 +135,7 @@
                                                 BITS_TO_LONGS(d->nr_pirqs));
         hvm_irq_dpci->mapping = xmalloc_array(unsigned long,
                                               BITS_TO_LONGS(d->nr_pirqs));
-        hvm_irq_dpci->hvm_timer = xmalloc_array(struct timer, nr_irqs);
+        hvm_irq_dpci->hvm_timer = xmalloc_array(struct timer, d->nr_pirqs);
         if ( !hvm_irq_dpci->mirq ||
              !hvm_irq_dpci->dirq_mask ||
              !hvm_irq_dpci->mapping ||
@@ -150,7 +150,7 @@
         bitmap_zero(hvm_irq_dpci->dirq_mask, d->nr_pirqs);
         bitmap_zero(hvm_irq_dpci->mapping, d->nr_pirqs);
         memset(hvm_irq_dpci->hvm_timer, 0,
-                nr_irqs * sizeof(*hvm_irq_dpci->hvm_timer));
+                d->nr_pirqs * sizeof(*hvm_irq_dpci->hvm_timer));
         for ( int i = 0; i < d->nr_pirqs; i++ ) {
             INIT_LIST_HEAD(&hvm_irq_dpci->mirq[i].digl_list);
             hvm_irq_dpci->mirq[i].gmsi.dest_vcpu_id = -1;
@@ -258,7 +258,6 @@
         /* Bind the same mirq once in the same domain */
         if ( !test_and_set_bit(machine_gsi, hvm_irq_dpci->mapping))
         {
-            unsigned int irq = domain_pirq_to_irq(d, machine_gsi);
             unsigned int share;
 
             hvm_irq_dpci->mirq[machine_gsi].dom = d;
@@ -278,14 +277,14 @@
 
             /* Init timer before binding */
             if ( pt_irq_need_timer(hvm_irq_dpci->mirq[machine_gsi].flags) )
-                init_timer(&hvm_irq_dpci->hvm_timer[irq],
+                init_timer(&hvm_irq_dpci->hvm_timer[machine_gsi],
                            pt_irq_time_out, &hvm_irq_dpci->mirq[machine_gsi], 
0);
             /* Deal with gsi for legacy devices */
             rc = pirq_guest_bind(d->vcpu[0], machine_gsi, share);
             if ( unlikely(rc) )
             {
                 if ( pt_irq_need_timer(hvm_irq_dpci->mirq[machine_gsi].flags) )
-                    kill_timer(&hvm_irq_dpci->hvm_timer[irq]);
+                    kill_timer(&hvm_irq_dpci->hvm_timer[machine_gsi]);
                 hvm_irq_dpci->mirq[machine_gsi].dom = NULL;
                 clear_bit(machine_gsi, hvm_irq_dpci->mapping);
                 list_del(&girq->list);
@@ -374,7 +373,7 @@
             pirq_guest_unbind(d, machine_gsi);
             msixtbl_pt_unregister(d, machine_gsi);
             if ( pt_irq_need_timer(hvm_irq_dpci->mirq[machine_gsi].flags) )
-                kill_timer(&hvm_irq_dpci->hvm_timer[domain_pirq_to_irq(d, 
machine_gsi)]);
+                kill_timer(&hvm_irq_dpci->hvm_timer[machine_gsi]);
             hvm_irq_dpci->mirq[machine_gsi].dom   = NULL;
             hvm_irq_dpci->mirq[machine_gsi].flags = 0;
             clear_bit(machine_gsi, hvm_irq_dpci->mapping);
@@ -516,7 +515,7 @@
          * will never be deasserted.
          */
         if ( pt_irq_need_timer(hvm_irq_dpci->mirq[pirq].flags) )
-            set_timer(&hvm_irq_dpci->hvm_timer[domain_pirq_to_irq(d, pirq)],
+            set_timer(&hvm_irq_dpci->hvm_timer[pirq],
                       NOW() + PT_IRQ_TIME_OUT);
         spin_unlock(&d->event_lock);
     }
@@ -544,7 +543,7 @@
          ! pt_irq_need_timer(hvm_irq_dpci->mirq[machine_gsi].flags) )
         return;
 
-    stop_timer(&hvm_irq_dpci->hvm_timer[domain_pirq_to_irq(d, machine_gsi)]);
+    stop_timer(&hvm_irq_dpci->hvm_timer[machine_gsi]);
     pirq_guest_eoi(d, machine_gsi);
 }
 
diff -r 4fe0442aa5b7 -r fbfee2a01a91 xen/drivers/passthrough/pci.c
--- a/xen/drivers/passthrough/pci.c     Tue Apr 05 13:03:29 2011 +0100
+++ b/xen/drivers/passthrough/pci.c     Tue Apr 05 13:05:05 2011 +0100
@@ -262,7 +262,7 @@
             pirq_guest_unbind(d, i);
 
             if ( pt_irq_need_timer(hvm_irq_dpci->mirq[i].flags) )
-                kill_timer(&hvm_irq_dpci->hvm_timer[domain_pirq_to_irq(d, i)]);
+                kill_timer(&hvm_irq_dpci->hvm_timer[i]);
 
             list_for_each_safe ( digl_list, tmp,
                                  &hvm_irq_dpci->mirq[i].digl_list )
diff -r 4fe0442aa5b7 -r fbfee2a01a91 xen/drivers/passthrough/vtd/x86/vtd.c
--- a/xen/drivers/passthrough/vtd/x86/vtd.c     Tue Apr 05 13:03:29 2011 +0100
+++ b/xen/drivers/passthrough/vtd/x86/vtd.c     Tue Apr 05 13:05:05 2011 +0100
@@ -101,7 +101,7 @@
                 hvm_pci_intx_deassert(d, digl->device, digl->intx);
                 if ( --dpci->mirq[i].pending == 0 )
                 {
-                    stop_timer(&dpci->hvm_timer[domain_pirq_to_irq(d, i)]);
+                    stop_timer(&dpci->hvm_timer[i]);
                     pirq_guest_eoi(d, i);
                 }
             }

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