[PATCH 10.1?] Revert "i386/cpu: Warn about why CPUID_EXT_PDCM is not available"

[PATCH 10.1?] Revert "i386/cpu: Warn about why CPUID_EXT_PDCM is not available"

[Paolo Bonzini]

This reverts commit 00268e00027459abede448662f8794d78eb4b0a4.
(The only conflict is in the !is_tdx_vm() part of the condition,
which is safe to keep).

mark_unavailable_features() actively blocks usage of the feature,
so it is a functional change, not merely a emitting warning.
The commit was intended to merely warn if PDCM was enabled when
the performance counters are not, so revert it.

Reported-by: Christian A. Ehrhardt <christian.ehrhardt@canonical.com>
Analyzed-by: Daniel P. Berrangé <berrange@redhat.com>
Analyzed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/cpu.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 673f8583c80..6d85149e6e1 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8946,9 +8946,6 @@ void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
 
     /* PDCM is fixed1 bit for TDX */
     if (!cpu->enable_pmu && !is_tdx_vm()) {
-        mark_unavailable_features(cpu, FEAT_1_ECX,
-                                  env->user_features[FEAT_1_ECX] & CPUID_EXT_PDCM,
-                                  "This feature is not available due to PMU being disabled");
         env->features[FEAT_1_ECX] &= ~CPUID_EXT_PDCM;
     }
 
-- 
2.50.1

Re: [PATCH 10.1?] Revert "i386/cpu: Warn about why CPUID_EXT_PDCM is not available"

[Daniel P. Berrangé]

On Tue, Aug 19, 2025 at 05:02:35PM +0200, Paolo Bonzini wrote:
> This reverts commit 00268e00027459abede448662f8794d78eb4b0a4.
> (The only conflict is in the !is_tdx_vm() part of the condition,
> which is safe to keep).
> 
> mark_unavailable_features() actively blocks usage of the feature,
> so it is a functional change, not merely a emitting warning.
> The commit was intended to merely warn if PDCM was enabled when
> the performance counters are not, so revert it.
> 
> Reported-by: Christian A. Ehrhardt <christian.ehrhardt@canonical.com>
> Analyzed-by: Daniel P. Berrangé <berrange@redhat.com>
> Analyzed-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  target/i386/cpu.c | 3 ---
>  1 file changed, 3 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 673f8583c80..6d85149e6e1 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -8946,9 +8946,6 @@ void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
>  
>      /* PDCM is fixed1 bit for TDX */
>      if (!cpu->enable_pmu && !is_tdx_vm()) {
> -        mark_unavailable_features(cpu, FEAT_1_ECX,
> -                                  env->user_features[FEAT_1_ECX] & CPUID_EXT_PDCM,
> -                                  "This feature is not available due to PMU being disabled");
>          env->features[FEAT_1_ECX] &= ~CPUID_EXT_PDCM;
>      }
>  
> -- 
> 2.50.1
> 

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|