From c0b6774d500d9a31da766213ebd8fd1bfed35b8f Mon Sep 17 00:00:00 2001
From: Jiri Denemark <jdenemar@redhat.com>
Date: Wed, 27 Nov 2024 08:34:52 +0100
Subject: [PATCH] cpu: Check blockers in virCPUCompareUnusable only if they
 exist

virCPUCompareUnusable can be called with blockers == NULL in case the
CPU model itself is usable (i.e., QEMU reports an empty list of
blockers), but the CPU definition contains some additional features
which have to be checked.

Fixes: v10.8.0-129-g5f8abbb7d0
Reported-by: Han Han <hhan@redhat.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Tested-by: Han Han <hhan@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
---
 src/cpu/cpu.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/cpu/cpu.c b/src/cpu/cpu.c
index ef515744ba..77afb7e9b3 100644
--- a/src/cpu/cpu.c
+++ b/src/cpu/cpu.c
@@ -201,11 +201,13 @@ virCPUCompareUnusable(virArch arch,
     char **blocker;
     size_t i;
 
-    for (blocker = blockers; *blocker; blocker++) {
-        if (!(feat = virCPUDefFindFeature(cpu, *blocker)) ||
-            feat->policy != VIR_CPU_FEATURE_DISABLE) {
-            virBufferAddStr(&features, *blocker);
-            virBufferAddLit(&features, ", ");
+    if (blockers) {
+        for (blocker = blockers; *blocker; blocker++) {
+            if (!(feat = virCPUDefFindFeature(cpu, *blocker)) ||
+                feat->policy != VIR_CPU_FEATURE_DISABLE) {
+                virBufferAddStr(&features, *blocker);
+                virBufferAddLit(&features, ", ");
+            }
         }
     }