From b6eb914119af7e724cbee27951cfba0a6afb3b97 Mon Sep 17 00:00:00 2001
Message-Id: <b6eb914119af7e724cbee27951cfba0a6afb3b97@dist-git>
From: Peter Krempa <pkrempa@redhat.com>
Date: Thu, 19 Jan 2023 15:06:11 +0100
Subject: [PATCH] qemu: hotplug: Remove legacy quirk for 'dimm' address
 generation

Commit b7798a07f93 (in fall of 2016) changed the way we generate aliases
for 'dimm' memory devices as the alias itself is part of the migration
stream section naming and thus must be treated as ABI.

The code added compatibility layer for VMs with memory hotplug started
with the old scheme to prevent from generating wrong aliases. The
compatibility layer broke though later when 'nvdimm' and 'pmem' devices
were introduced as it wrongly detected them as old configuration.

Now rather than attempting to fix the legacy compat layer to treat other
devices properly we'll be better off simply removing it as it's
extremely unlikely that somebody has a VM started in 2016 running with
today's libvirt and attempts to hotplug more memory.

This fixes a corner case when a user hot-adds a 'dimm' into a VM with a
'dimm' and a 'nvdimm' after restart of libvirtd and then attempts to
migrate the VM.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2158701
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
(cherry picked from commit 50ce3463d514950350143f03e8421c8c31889c5d)
---
 src/qemu/qemu_hotplug.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 026e1ee5ad..5840504d13 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2275,9 +2275,7 @@ qemuDomainAttachMemory(virQEMUDriver *driver,
         goto cleanup;
     releaseaddr = true;
 
-    /* in cases where we are using a VM with aliases generated according to the
-     * index of the memory device we need to keep continue using that scheme */
-    if (qemuAssignDeviceMemoryAlias(vm->def, mem, priv->memAliasOrderMismatch) < 0)
+    if (qemuAssignDeviceMemoryAlias(vm->def, mem, false) < 0)
         goto cleanup;
 
     objalias = g_strdup_printf("mem%s", mem->info.alias);
-- 
2.39.1