Re: [PATCH v4 5/8] x86/mce: Convert family/model mixed checks to VFM-based checks

[Yazen Ghannam]

On Mon, Nov 11, 2024 at 02:04:25PM +0800, Qiuxu Zhuo wrote:
> Convert family/model mixed checks to VFM-based checks to make
> the code more compact.
> 
> Suggested-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
> Suggested-by: Dave Hansen <dave.hansen@xxxxxxxxx>
> Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
> ---
> Changes in v4:
>   - No changes but rebased.
> 
> Changes in v3:
>   - Newly added.
> 
>  arch/x86/kernel/cpu/mce/core.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index 3855ec2ed0e0..d288cc7390f6 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -1954,6 +1954,10 @@ static void apply_quirks_intel(struct cpuinfo_x86 *c)
>  {
>  	struct mce_bank *mce_banks = this_cpu_ptr(mce_banks_array);
>  
> +	/* Older CPUs (prior to family 6) don't need quirks. */
> +	if (c->x86_vfm < INTEL_PENTIUM_PRO)
> +		return;
> +

Is it possible for pre-"family 6" to get here?

Family 5 is "ancient" which has its own MCE init path. And I assume
anything older doesn't support MCE/MCA. Is this correct?

>  	/*
>  	 * SDM documents that on family 6 bank 0 should not be written
>  	 * because it aliases to another special BIOS controlled
> @@ -1962,22 +1966,21 @@ static void apply_quirks_intel(struct cpuinfo_x86 *c)
>  	 * Don't ignore bank 0 completely because there could be a
>  	 * valid event later, merely don't write CTL0.
>  	 */
> -	if (c->x86 == 6 && c->x86_model < 0x1A && this_cpu_read(mce_num_banks) > 0)
> +	if (c->x86_vfm < INTEL_NEHALEM_EP && this_cpu_read(mce_num_banks) > 0)

The "> 0" is not needed, since mce_num_banks is unsigned int. 

Otherwise, looks good.

Reviewed-by: Yazen Ghannam <yazen.ghannam@xxxxxxx>

Thanks,
Yazen