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-rw-r--r--main/xen/xsa344-1.patch137
1 files changed, 137 insertions, 0 deletions
diff --git a/main/xen/xsa344-1.patch b/main/xen/xsa344-1.patch
new file mode 100644
index 0000000000..38340753eb
--- /dev/null
+++ b/main/xen/xsa344-1.patch
@@ -0,0 +1,137 @@
+From: Jan Beulich <jbeulich@suse.com>
+Subject: evtchn: arrange for preemption in evtchn_destroy()
+
+Especially closing of fully established interdomain channels can take
+quite some time, due to the locking involved. Therefore we shouldn't
+assume we can clean up still active ports all in one go. Besides adding
+the necessary preemption check, also avoid pointlessly starting from
+(or now really ending at) 0; 1 is the lowest numbered port which may
+need closing.
+
+Since we're now reducing ->valid_evtchns, free_xen_event_channel(),
+and (at least to be on the safe side) notify_via_xen_event_channel()
+need to cope with attempts to close / unbind from / send through already
+closed (and no longer valid, as per port_is_valid()) ports.
+
+This is part of XSA-344.
+
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Acked-by: Julien Grall <jgrall@amazon.com>
+Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
+---
+v8: Drop ->active->evtchns part of main loop condition. Drop BUG_ON()
+ conversion in evtchn_close().
+v7: Comment the barriers added in v6.
+v6: Add barriers ahead of new ->is_dying checks.
+v5: Also adjust BUG_ON() in evtchn_close().
+v4: New.
+
+--- a/xen/common/domain.c
++++ b/xen/common/domain.c
+@@ -715,12 +715,14 @@ int domain_kill(struct domain *d)
+ return domain_kill(d);
+ d->is_dying = DOMDYING_dying;
+ argo_destroy(d);
+- evtchn_destroy(d);
+ gnttab_release_mappings(d);
+ vnuma_destroy(d->vnuma);
+ domain_set_outstanding_pages(d, 0);
+ /* fallthrough */
+ case DOMDYING_dying:
++ rc = evtchn_destroy(d);
++ if ( rc )
++ break;
+ rc = domain_relinquish_resources(d);
+ if ( rc != 0 )
+ break;
+--- a/xen/common/event_channel.c
++++ b/xen/common/event_channel.c
+@@ -1297,7 +1297,16 @@ int alloc_unbound_xen_event_channel(
+
+ void free_xen_event_channel(struct domain *d, int port)
+ {
+- BUG_ON(!port_is_valid(d, port));
++ if ( !port_is_valid(d, port) )
++ {
++ /*
++ * Make sure ->is_dying is read /after/ ->valid_evtchns, pairing
++ * with the spin_barrier() and BUG_ON() in evtchn_destroy().
++ */
++ smp_rmb();
++ BUG_ON(!d->is_dying);
++ return;
++ }
+
+ evtchn_close(d, port, 0);
+ }
+@@ -1309,7 +1318,17 @@ void notify_via_xen_event_channel(struct
+ struct domain *rd;
+ unsigned long flags;
+
+- ASSERT(port_is_valid(ld, lport));
++ if ( !port_is_valid(ld, lport) )
++ {
++ /*
++ * Make sure ->is_dying is read /after/ ->valid_evtchns, pairing
++ * with the spin_barrier() and BUG_ON() in evtchn_destroy().
++ */
++ smp_rmb();
++ ASSERT(ld->is_dying);
++ return;
++ }
++
+ lchn = evtchn_from_port(ld, lport);
+
+ spin_lock_irqsave(&lchn->lock, flags);
+@@ -1380,8 +1399,7 @@ int evtchn_init(struct domain *d, unsign
+ return 0;
+ }
+
+-
+-void evtchn_destroy(struct domain *d)
++int evtchn_destroy(struct domain *d)
+ {
+ unsigned int i;
+
+@@ -1390,14 +1408,29 @@ void evtchn_destroy(struct domain *d)
+ spin_barrier(&d->event_lock);
+
+ /* Close all existing event channels. */
+- for ( i = 0; port_is_valid(d, i); i++ )
++ for ( i = d->valid_evtchns; --i; )
++ {
+ evtchn_close(d, i, 0);
+
++ /*
++ * Avoid preempting when called from domain_create()'s error path,
++ * and don't check too often (choice of frequency is arbitrary).
++ */
++ if ( i && !(i & 0x3f) && d->is_dying != DOMDYING_dead &&
++ hypercall_preempt_check() )
++ {
++ write_atomic(&d->valid_evtchns, i);
++ return -ERESTART;
++ }
++ }
++
+ ASSERT(!d->active_evtchns);
+
+ clear_global_virq_handlers(d);
+
+ evtchn_fifo_destroy(d);
++
++ return 0;
+ }
+
+
+--- a/xen/include/xen/sched.h
++++ b/xen/include/xen/sched.h
+@@ -138,7 +138,7 @@ struct evtchn
+ } __attribute__((aligned(64)));
+
+ int evtchn_init(struct domain *d, unsigned int max_port);
+-void evtchn_destroy(struct domain *d); /* from domain_kill */
++int evtchn_destroy(struct domain *d); /* from domain_kill */
+ void evtchn_destroy_final(struct domain *d); /* from complete_domain_destroy */
+
+ struct waitqueue_vcpu;