Re: [RFC PATCH 2/4] i386: Extract a common fucntion to setup value of MSR_CORE_THREAD_COUNT

[Igor Mammedov]

On Thu, 5 Dec 2024 22:38:41 +0100
Philippe Mathieu-Daudé <philmd@linaro.org> wrote:

> Hi Xiaoyao,
> 
> On 5/12/24 15:57, Xiaoyao Li wrote:
> > There are duplicated code to setup the value of MSR_CORE_THREAD_COUNT.
> > Extract a common function for it.
> > 
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> > ---
> >   target/i386/cpu.h                    | 11 +++++++++++
> >   target/i386/hvf/x86_emu.c            |  3 +--
> >   target/i386/kvm/kvm.c                |  5 +----
> >   target/i386/tcg/sysemu/misc_helper.c |  3 +--
> >   4 files changed, 14 insertions(+), 8 deletions(-)
> > 
> > diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> > index 4c239a6970fd..5795a497e567 100644
> > --- a/target/i386/cpu.h
> > +++ b/target/i386/cpu.h
> > @@ -2390,6 +2390,17 @@ static inline void 
> > cpu_x86_load_seg_cache_sipi(X86CPU *cpu,
> >       cs->halted = 0;
> >   }
> >   
> > +static inline uint64_t cpu_x86_get_msr_core_thread_count(X86CPU *cpu)  
> 
> Please do not add more inlined functions in this huge file, the
> inlining performance isn't justified at all.
> 
> target/i386/cpu-sysemu.c looks the correct place for this helper.

ack

> 
> > +{
> > +    CPUState *cs = CPU(cpu);
> > +    uint64_t val;
> > +
> > +    val = cs->nr_threads * cs->nr_cores;  /* thread count, bits 15..0 */
> > +    val |= ((uint32_t)cs->nr_cores << 16); /* core count, bits 31..16 */  
> 
> Personally I'd change to:
> 
>         return deposit64(cs->nr_threads * cs->nr_cores, 16, 16,
>                          cs->nr_cores);
that I wouldn't do in this patch to make it easier to compare apples to apples
That however could be a separate patch on top

> > +
> > +    return val;
> > +}  
>