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

From: K Prateek Nayak <kprateek.nayak@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, rafael@kernel.org, lenb@kernel.org,
	linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org,
	dave.hansen@linux.intel.com, tglx@linutronix.de, andi@lisas.de,
	puwen@hygon.cn, mario.limonciello@amd.com, peterz@infradead.org,
	rui.zhang@intel.com, gpiccoli@igalia.com,
	daniel.lezcano@linaro.org, ananth.narayan@amd.com,
	gautham.shenoy@amd.com, Calvin Ong <calvin.ong@amd.com>,
	stable@vger.kernel.org, regressions@lists.linux.dev
Subject: Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture
Date: Wed, 21 Sep 2022 16:09:16 +0530	[thread overview]
Message-ID: <f927f969-028a-4ad4-7776-527ed537c77f@amd.com> (raw)
In-Reply-To: <YyrPqlo/ysCeh4qU@zn.tnic>

Hello Boris,

On 9/21/2022 2:17 PM, Borislav Petkov wrote:
> On Wed, Sep 21, 2022 at 12:06:38PM +0530, K Prateek Nayak wrote:
>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>> index 16a1663d02d4..18850aa2b79b 100644
>> --- a/drivers/acpi/processor_idle.c
>> +++ b/drivers/acpi/processor_idle.c
>> @@ -528,8 +528,11 @@ static int acpi_idle_bm_check(void)
>>  static void wait_for_freeze(void)
>>  {
>>  #ifdef	CONFIG_X86
>> -	/* No delay is needed if we are in guest */
>> -	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
>> +	/*
>> +	 * 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))
> 
> s/boot_cpu_has/cpu_feature_enabled/g

I was not aware of cpu_feature_enabled() and it makes perfect sense to
use it here. Thank you for bringing it to my notice.
I'll make this change in v2.

> 
> while at it.
> 

--
Thanks and Regards,
Prateek