Re: [PATCH v4 21/21] i386: Add new property to control L2 cache topo in CPUID.04H

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 14/9/23 09:21, Zhao Liu wrote:
> From: Zhao Liu <zhao1.liu@intel.com>
> 
> The property x-l2-cache-topo will be used to change the L2 cache
> topology in CPUID.04H.
> 
> Now it allows user to set the L2 cache is shared in core level or
> cluster level.
> 
> If user passes "-cpu x-l2-cache-topo=[core|cluster]" then older L2 cache
> topology will be overrode by the new topology setting.
> 
> Here we expose to user "cluster" instead of "module", to be consistent
> with "cluster-id" naming.
> 
> Since CPUID.04H is used by intel CPUs, this property is available on
> intel CPUs as for now.
> 
> When necessary, it can be extended to CPUID.8000001DH for AMD CPUs.
> 
> (Tested the cache topology in CPUID[0x04] leaf with "x-l2-cache-topo=[
> core|cluster]", and tested the live migration between the QEMUs w/ &
> w/o this patch series.)
> 
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> Tested-by: Yongwei Ma <yongwei.ma@intel.com>
> ---
> Changes since v3:
>   * Add description about test for live migration compatibility. (Babu)
> 
> Changes since v1:
>   * Rename MODULE branch to CPU_TOPO_LEVEL_MODULE to match the previous
>     renaming changes.
> ---
>   target/i386/cpu.c | 34 +++++++++++++++++++++++++++++++++-
>   target/i386/cpu.h |  2 ++
>   2 files changed, 35 insertions(+), 1 deletion(-)


> @@ -8079,6 +8110,7 @@ static Property x86_cpu_properties[] = {
>                        false),
>       DEFINE_PROP_BOOL("x-intel-pt-auto-level", X86CPU, intel_pt_auto_level,
>                        true),
> +    DEFINE_PROP_STRING("x-l2-cache-topo", X86CPU, l2_cache_topo_level),

We use the 'x-' prefix for unstable features, is it the case here?

>       DEFINE_PROP_END_OF_LIST()
>   };