From 67ace39b253ed5ae465275bc870f7e495547658b Mon Sep 17 00:00:00 2001
From: Alexey Kardashevskiy <aik@ozlabs.ru>
Date: Thu, 21 Sep 2017 18:51:05 +1000
Subject: [PATCH] memory: Do not allocate FlatView in address_space_init
This creates a new AS object without any FlatView as
memory_region_transaction_commit() may want to reuse the empty FV.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <20170921085110.25598-14-aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
memory.c | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/memory.c b/memory.c
index 8ee3c81862a..3f6dd403033 100644
--- a/memory.c
+++ b/memory.c
@@ -967,22 +967,37 @@ static void flatviews_reset(void)
static void address_space_set_flatview(AddressSpace *as)
{
- FlatView *old_view = address_space_get_flatview(as);
+ FlatView *old_view = address_space_to_flatview(as);
MemoryRegion *physmr = memory_region_get_flatview_root(as->root);
FlatView *new_view = g_hash_table_lookup(flat_views, physmr);
assert(new_view);
+ if (old_view == new_view) {
+ return;
+ }
+
+ if (old_view) {
+ flatview_ref(old_view);
+ }
+
flatview_ref(new_view);
if (!QTAILQ_EMPTY(&as->listeners)) {
- address_space_update_topology_pass(as, old_view, new_view, false);
- address_space_update_topology_pass(as, old_view, new_view, true);
+ FlatView tmpview = { .nr = 0 }, *old_view2 = old_view;
+
+ if (!old_view2) {
+ old_view2 = &tmpview;
+ }
+ address_space_update_topology_pass(as, old_view2, new_view, false);
+ address_space_update_topology_pass(as, old_view2, new_view, true);
}
/* Writes are protected by the BQL. */
atomic_rcu_set(&as->current_map, new_view);
- flatview_unref(old_view);
+ if (old_view) {
+ flatview_unref(old_view);
+ }
/* Note that all the old MemoryRegions are still alive up to this
* point. This relieves most MemoryListeners from the need to
@@ -990,7 +1005,9 @@ static void address_space_set_flatview(AddressSpace *as)
* outside the iothread mutex, in which case precise reference
* counting is necessary.
*/
- flatview_unref(old_view);
+ if (old_view) {
+ flatview_unref(old_view);
+ }
}
void memory_region_transaction_begin(void)
@@ -2708,7 +2725,7 @@ void address_space_init(AddressSpace *as, MemoryRegion *root, const char *name)
as->ref_count = 1;
as->root = root;
as->malloced = false;
- as->current_map = flatview_new(root);
+ as->current_map = NULL;
as->ioeventfd_nb = 0;
as->ioeventfds = NULL;
QTAILQ_INIT(&as->listeners);
--
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