When updating the guest CPU model and the deprecated_features attribute
is set to on, only enable the features the model can actually enable.

While host-model would normally just enable these features without
intervention (and without the presence of the deprecated_features
attribute), custom models would see no changes to their feature set
without these changes.

This is useful for e.g. testing CPU models.

Fixes: f279ea36 (qemu: process: refactor deprecated features code)
Signed-off-by: Collin Walling <walling@linux.ibm.com>
---
 src/qemu/qemu_capabilities.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 2dfdedfa1a..cee7a0f5ef 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -3437,15 +3437,24 @@ virQEMUCapsUpdateCPUDeprecatedFeatures(virQEMUCaps *qemuCaps,
                                        virCPUFeaturePolicy policy)
 {
     qemuMonitorCPUModelInfo *modelInfo;
+    GStrv props;
     size_t i;
 
     modelInfo = virQEMUCapsGetCPUModelInfo(qemuCaps, virtType);
 
-    if (!modelInfo || !modelInfo->full_dep_props)
+    if (!modelInfo)
         return;
 
-    for (i = 0; i < g_strv_length(modelInfo->full_dep_props); i++) {
-        virCPUDefUpdateFeature(cpu, modelInfo->full_dep_props[i], policy);
+    /* Only allow policy "require" on features that are actually
+     * supported on the CPU model */
+    if (policy == VIR_CPU_FEATURE_REQUIRE) {
+        props = modelInfo->static_dep_props;
+    } else {
+        props = modelInfo->full_dep_props;
+    }
+
+    for (i = 0; i < g_strv_length(props); i++) {
+        virCPUDefUpdateFeature(cpu, props[i], policy);
     }
 }
 
-- 
2.51.1

Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>

On 11/20/25 23:34, Collin Walling wrote:
> When updating the guest CPU model and the deprecated_features attribute
> is set to on, only enable the features the model can actually enable.
> 
> While host-model would normally just enable these features without
> intervention (and without the presence of the deprecated_features
> attribute), custom models would see no changes to their feature set
> without these changes.
> 
> This is useful for e.g. testing CPU models.
> 
> Fixes: f279ea36 (qemu: process: refactor deprecated features code)
> Signed-off-by: Collin Walling <walling@linux.ibm.com>
> ---
>   src/qemu/qemu_capabilities.c | 15 ++++++++++++---
>   1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 2dfdedfa1a..cee7a0f5ef 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -3437,15 +3437,24 @@ virQEMUCapsUpdateCPUDeprecatedFeatures(virQEMUCaps *qemuCaps,
>                                          virCPUFeaturePolicy policy)
>   {
>       qemuMonitorCPUModelInfo *modelInfo;
> +    GStrv props;
>       size_t i;
>   
>       modelInfo = virQEMUCapsGetCPUModelInfo(qemuCaps, virtType);
>   
> -    if (!modelInfo || !modelInfo->full_dep_props)
> +    if (!modelInfo)
>           return;
>   
> -    for (i = 0; i < g_strv_length(modelInfo->full_dep_props); i++) {
> -        virCPUDefUpdateFeature(cpu, modelInfo->full_dep_props[i], policy);
> +    /* Only allow policy "require" on features that are actually
> +     * supported on the CPU model */
> +    if (policy == VIR_CPU_FEATURE_REQUIRE) {
> +        props = modelInfo->static_dep_props;
> +    } else {
> +        props = modelInfo->full_dep_props;
> +    }
> +
> +    for (i = 0; i < g_strv_length(props); i++) {
> +        virCPUDefUpdateFeature(cpu, props[i], policy);
>       }
>   }
>   


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

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