Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture

[Dave Hansen]

On 9/20/22 23:36, K Prateek Nayak wrote:
> +	/*
> +	 * No delay is needed if we are in guest or on a processor
> +	 * based on the Zen microarchitecture.
> +	 */
> +	if (boot_cpu_has(X86_FEATURE_HYPERVISOR) || boot_cpu_has(X86_FEATURE_ZEN))
>  		return;

In the end, the delay is because of buggy, circa 2006 chipsets?  So, we
use a CPU vendor specific check to approximate that the chipset is
recent and not affected by the bug?  If so, is there no better way to
check for a newer chipset than this?

Do X86_FEATURE_ZEN CPUs just have unusually painful
inl(acpi_fadt.xpm_tmr_blk.address) implementations?  Is that why we
noticed all of a sudden?