# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1247483825 -3600
# Node ID 0d4406bc5cb7b0369dacfa5607550758fac672de
# Parent f17c897546bf679641053ca586d08e2d393339a3
Allow XENMEM_exchange to support exchange on foreign domains.
Signed-off-by: Yunhong Jiang <yunhong.jiang@xxxxxxxxx>
---
xen/common/memory.c | 61 ++++++++++++++++++++++++++++++++++++++++------------
1 files changed, 47 insertions(+), 14 deletions(-)
diff -r f17c897546bf -r 0d4406bc5cb7 xen/common/memory.c
--- a/xen/common/memory.c Mon Jul 13 11:52:49 2009 +0100
+++ b/xen/common/memory.c Mon Jul 13 12:17:05 2009 +0100
@@ -265,16 +265,22 @@ static long memory_exchange(XEN_GUEST_HA
out_chunk_order = exch.in.extent_order - exch.out.extent_order;
}
- /*
- * Only support exchange on calling domain right now. Otherwise there are
- * tricky corner cases to consider (e.g., dying domain).
- */
- if ( unlikely(exch.in.domid != DOMID_SELF) )
- {
- rc = IS_PRIV(current->domain) ? -EINVAL : -EPERM;
- goto fail_early;
- }
- d = current->domain;
+ if ( likely(exch.in.domid == DOMID_SELF) )
+ {
+ d = rcu_lock_current_domain();
+ }
+ else
+ {
+ if ( (d = rcu_lock_domain_by_id(exch.in.domid)) == NULL )
+ goto fail_early;
+
+ if ( !IS_PRIV_FOR(current->domain, d) )
+ {
+ rcu_unlock_domain(d);
+ rc = -EPERM;
+ goto fail_early;
+ }
+ }
memflags |= MEMF_bits(domain_clamp_alloc_bitsize(
d,
@@ -292,6 +298,7 @@ static long memory_exchange(XEN_GUEST_HA
if ( hypercall_preempt_check() )
{
exch.nr_exchanged = i << in_chunk_order;
+ rcu_unlock_domain(d);
if ( copy_field_to_guest(arg, &exch, nr_exchanged) )
return -EFAULT;
return hypercall_create_continuation(
@@ -362,7 +369,32 @@ static long memory_exchange(XEN_GUEST_HA
{
if ( assign_pages(d, page, exch.out.extent_order,
MEMF_no_refcount) )
- BUG();
+ {
+ unsigned long dec_count;
+ bool_t drop_dom_ref;
+
+ /*
+ * Pages in in_chunk_list is stolen without
+ * decreasing the tot_pages. If the domain is dying when
+ * assign pages, we need decrease the count. For those pages
+ * that has been assigned, it should be covered by
+ * domain_relinquish_resources().
+ */
+ dec_count = (((1UL << exch.in.extent_order) *
+ (1UL << in_chunk_order)) -
+ (j * (1UL << exch.out.extent_order)));
+
+ spin_lock(&d->page_alloc_lock);
+ d->tot_pages -= dec_count;
+ drop_dom_ref = (dec_count && !d->tot_pages);
+ spin_unlock(&d->page_alloc_lock);
+
+ if ( drop_dom_ref )
+ put_domain(d);
+
+ free_domheap_pages(page, exch.out.extent_order);
+ goto dying;
+ }
/* Note that we ignore errors accessing the output extent list. */
(void)__copy_from_guest_offset(
@@ -378,15 +410,15 @@ static long memory_exchange(XEN_GUEST_HA
(void)__copy_to_guest_offset(
exch.out.extent_start, (i<<out_chunk_order)+j, &mfn, 1);
}
-
j++;
}
- BUG_ON(j != (1UL << out_chunk_order));
+ BUG_ON( !(d->is_dying) && (j != (1UL << out_chunk_order)) );
}
exch.nr_exchanged = exch.in.nr_extents;
if ( copy_field_to_guest(arg, &exch, nr_exchanged) )
rc = -EFAULT;
+ rcu_unlock_domain(d);
return rc;
/*
@@ -398,7 +430,8 @@ static long memory_exchange(XEN_GUEST_HA
while ( (page = page_list_remove_head(&in_chunk_list)) )
if ( assign_pages(d, page, 0, MEMF_no_refcount) )
BUG();
-
+ dying:
+ rcu_unlock_domain(d);
/* Free any output pages we managed to allocate. */
while ( (page = page_list_remove_head(&out_chunk_list)) )
free_domheap_pages(page, exch.out.extent_order);
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