Re: [PATCH v2 4/7] i386/cpu: Fix number of addressable IDs field for CPUID.01H.EBX[23:16]

[Zhao Liu <zhao1.liu@intel.com>]

> This makes sense.
> 
> In this case though, the next patch, a62fef5829956 "i386/cpu: Fix cpu
> number overflow in CPUID.01H.EBX[23:16]", becomes a one-liner:
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 2c9517f56d..5e55dd9ee5 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -6828,7 +6828,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> uint32_t count,
>          }
>          *edx = env->features[FEAT_1_EDX];
>          if (threads_per_pkg > 1) {
> -            *ebx |= threads_per_pkg << 16;
> +            /* Fixup overflow: max value for bits 23-16 is 255. */
> +            *ebx |= MIN(threads_per_pkg, 255) << 16;
>          }
>          if (!cpu->enable_pmu) {
>              *ecx &= ~CPUID_EXT_PDCM;
> 
> Is it okay with you, or maybe should I drop this change for 10.0.x
> too?

Yes, it's okay. This commit I should have cc'd stable, as it is indeed a
reported bug.

And after this commit, there're another 2 commits to avoid overflow:

* commit 3e86124e7cb9 ("i386/cpu: Fix overflow of cache topology fields
  in CPUID.04H")
* commit 5d21ee453ad8 ("i386/cpu: Honor maximum value for CPUID.
  8000001DH.EAX[25:14]")

I think these two could also be stable v10.0.x materials.

Thanks,
Zhao