From be6e92f541ab27019de530f1f08ec9b2912765a9 Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Wed, 6 Apr 2016 17:32:12 +0200
Subject: [PATCH] qemu: alias: Fix calculation of memory device aliases

For device hotplug, the new alias ID needs to be checked in the list
rather than using the count of devices. Unplugging a device that is not
last in the array will make further hotplug impossible due to alias
collision.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1324551
---
 src/qemu/qemu_alias.c   | 20 ++++++++++++++++++++
 src/qemu/qemu_alias.h   |  3 +++
 src/qemu/qemu_hotplug.c |  2 +-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c
index 330a391de4..ade2033e27 100644
--- a/src/qemu/qemu_alias.c
+++ b/src/qemu/qemu_alias.c
@@ -401,6 +401,26 @@ qemuAssignDeviceRNGAlias(virDomainDefPtr def,
 }
 
 
+int
+qemuAssignDeviceMemoryAlias(virDomainDefPtr def,
+                            virDomainMemoryDefPtr mem)
+{
+    size_t i;
+    int maxidx = 0;
+    int idx;
+
+    for (i = 0; i < def->nmems; i++) {
+        if ((idx = qemuDomainDeviceAliasIndex(&def->mems[i]->info, "dimm")) >= maxidx)
+            maxidx = idx + 1;
+    }
+
+    if (virAsprintf(&mem->info.alias, "dimm%d", maxidx) < 0)
+        return -1;
+
+    return 0;
+}
+
+
 int
 qemuAssignDeviceAliases(virDomainDefPtr def, virQEMUCapsPtr qemuCaps)
 {
diff --git a/src/qemu/qemu_alias.h b/src/qemu/qemu_alias.h
index f09466d77e..2d7bc9b376 100644
--- a/src/qemu/qemu_alias.h
+++ b/src/qemu/qemu_alias.h
@@ -57,6 +57,9 @@ int qemuAssignDeviceRedirdevAlias(virDomainDefPtr def,
 int qemuAssignDeviceRNGAlias(virDomainDefPtr def,
                              virDomainRNGDefPtr rng);
 
+int qemuAssignDeviceMemoryAlias(virDomainDefPtr def,
+                                virDomainMemoryDefPtr mems);
+
 int qemuAssignDeviceAliases(virDomainDefPtr def, virQEMUCapsPtr qemuCaps);
 
 int qemuDomainDeviceAliasIndex(const virDomainDeviceInfo *info,
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index b9a8b51594..bd1a128090 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -1751,7 +1751,7 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
     if (qemuDomainDefValidateMemoryHotplug(vm->def, priv->qemuCaps, mem) < 0)
         goto cleanup;
 
-    if (virAsprintf(&mem->info.alias, "dimm%zu", vm->def->nmems) < 0)
+    if (qemuAssignDeviceMemoryAlias(vm->def, mem) < 0)
         goto cleanup;
 
     if (virAsprintf(&objalias, "mem%s", mem->info.alias) < 0)
-- 
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