From 5bfc2be91ba382cf0c0353794ff9289cb9b064de Mon Sep 17 00:00:00 2001

From: David Gibson <dgibson@redhat.com>

Date: Thu, 16 Nov 2017 03:07:26 +0100

Subject: [PATCH 22/30] memory: Do not allocate FlatView in address_space_init

RH-Author: David Gibson <dgibson@redhat.com>

Message-id: <20171116030732.8560-17-dgibson@redhat.com>

Patchwork-id: 77705

O-Subject: [PATCH 16/22] memory: Do not allocate FlatView in address_space_init

Bugzilla: 1481593

RH-Acked-by: Thomas Huth <thuth@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>

RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

From: Alexey Kardashevskiy <aik@ozlabs.ru>

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>

(cherry picked from commit 67ace39b253ed5ae465275bc870f7e495547658b)

Signed-off-by: David Gibson <dgibson@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 memory.c | 29 +++++++++++++++++++++++------

 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/memory.c b/memory.c

index f0c8642..6914d87 100644

--- a/memory.c

+++ b/memory.c

@@ -966,22 +966,37 @@ 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

@@ -989,7 +1004,9 @@ 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)

@@ -2707,7 +2724,7 @@ 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);

-- 

1.8.3.1