Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <f927f969-028a-4ad4-7776-527ed537c77f@amd.com>
Date:   Wed, 21 Sep 2022 16:09:16 +0530
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.13.0
Subject: Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors
 based on the Zen microarchitecture
Content-Language: en-US
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
References: <20220921063638.2489-1-kprateek.nayak@amd.com>
 <YyrPqlo/ysCeh4qU@zn.tnic>
From:   K Prateek Nayak <kprateek.nayak@amd.com>
In-Reply-To: <YyrPqlo/ysCeh4qU@zn.tnic>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?ZDR5c0RWb0hvWm83REd6a1ZrSE8vK2czODhpOHh2MjBlRGY2VEg2ZnFGeFVy?=
 =?utf-8?B?VThOSkU3bUpCSFhvakhOUlhzWUNjckU5WlRITU1oWDA2aDkwYjc4MGw2ZkFP?=
 =?utf-8?B?TDA2UzhCbitORklDTmk0YlFHRkJ3TXZJbnFvZVQ3YjNYZlRGTUp2OWVrSzE5?=
 =?utf-8?B?SDEzUmtERUFWREkwSW9aWXNnVlJXQnRYWFdvUm1oMmRrM0hPYkQ4VWErTm1X?=
 =?utf-8?B?K1JGSzc3ZkppRzFVcDBOME9Qc3UxeXdIS1h6WXlSam9SVGVibzkybTJLNG1k?=
 =?utf-8?B?eEYybEpKWnVKR1pIcjZNVFhYdlZmclVqdHlJQlNZQVRSZUN0YTVpRjgxbzhD?=
 =?utf-8?B?VDA4RktXd3NBQytQQ0lzVEdST1d4NGIraGkxQjdxSXBjNHhxNVVCOHZ0dTJR?=
 =?utf-8?B?aWprUGdvbG95cFJId0YvMVRPS1Y3V3JRbWN0OXIwRFMzR0ljUlVacUhpamlu?=
 =?utf-8?B?Nmp5cE92NDcrYURsYjRwbTRlTDVyZlVjZ014cFZCbm8wV1NWNXdUb00xTDFM?=
 =?utf-8?B?SldxMUpXdHU2NkFKS2ZrQW9FSHE2ek54aTZhejh5blRrY0pQbGFVVlNVMTFK?=
 =?utf-8?B?WVZEWW95dGtyYTR4RXlOUENkWmt0SkdGSkJFMUR5UEZPUVErRWFzaW1jdFZ0?=
 =?utf-8?B?N2ZTSCtXNlYwWTh4V0hDakR5Ylh4UVJWZ0FIeVZBa1c1UEgrYnRVcVlmSVdN?=
 =?utf-8?B?S0M3UEpiVUUzZlRNTzV4WGVScG5Pck5nZzF1YTZ5VDRXS1NmSTNnSTYvMlAy?=
 =?utf-8?B?TWtrMWtRMy9jN2hCQ2NIS0l2WG9tMFBoMWZzVnFYUHVSdlM3Q3hKNVB5eEJz?=
 =?utf-8?B?MmNDZUVKd25zd0R3Q1hQSHI2RGw2YWVJSEpvd2gwQ0tERUJyT0JWNC85V053?=
 =?utf-8?B?NW5yMHJaeDl2QXlONTdxbGpnT1RTUlhTWjZrbVp0NlFFeElUYitZMVltbFRz?=
 =?utf-8?B?M2RmQ3RFSWtheFQxOEU3RU8wL01pWjliQSsxSStadmcwNFdoS0RqQTFLRkVs?=
 =?utf-8?B?SHp0aE00OHBHUjc5U29lVElzR09MS0QrQ0oyYUNRY3JoU3BSaFpnd0RmRHRP?=
 =?utf-8?B?dUxxRmdjQVBVTnh6b1g0OU1iYUhNQWR2WkVBVXdUdUorWlo1OW4yYUEvQ0lz?=
 =?utf-8?B?b0U4SjNJUjNnSlRQZE5VWmo1aE4rWHFXM1ZXQ0I1dURBQk9vcGF1SXV1L1ky?=
 =?utf-8?B?dGtZQ0VzRGVJVmY3OXdyVjd0VUJ0WG5yWGkwME9tVEhVWHVmZUFkanBzaVkw?=
 =?utf-8?B?dXd3OGk4UVJYMGdaZVRqZkMxWVJqOC9UMk5sY0ZhMWVHY3BrWGxoTTQwUFRJ?=
 =?utf-8?B?emFxTXVkMDNNUUxNdGlqYjFCMHlxZUEvaW42bW1zQ25xT0VpRnZhTEI3SU5F?=
 =?utf-8?B?aldJeStjL2tXUGhrNi9HOEsxcEdnNUZZamhVaFZwSnhKbzNvdGE2OXF4Um8y?=
 =?utf-8?B?SWpia0M2Vk1mRXhjZVBPRXVmaFZwdWRFM3dyaGtpQTVPUEJha2xwbStHNTN5?=
 =?utf-8?B?UW5rZ2pSenhzZHdTYkw2ZnBZVWs1bUxVek01U1V2SDZmejNGdVVUZmJBWElS?=
 =?utf-8?B?ZU0wV2hxaVNOM0ZpN2JUSWpwUHdkRm1UdGhKMEM4bkplRTZwVHRhcTUvYm9T?=
 =?utf-8?B?ekl4RFRld054VEI2L1ZnYkVuendOSWx3Tk1vWS9GdW53eUpZWXQ1cTQxNUlE?=
 =?utf-8?B?MW5ZNGowQTFTZXVsMHBoNUpkbXRmYllCbmZQanF0WnRqS2ZRcXdLcEM1RU5Q?=
 =?utf-8?B?bTMyU3FBMWNEcERIMlFLVjNTd3BuNURVazFyMTh2clNiaExBVTVnZXNwK3k4?=
 =?utf-8?B?bS9VT211OWdXeXdKZ09SbXRQUEhyYk5xT1FJR281T1ljZE1SeWluNExmOWls?=
 =?utf-8?B?M3JwUkY4RmYweXlPMDAzNkY0KzlTN0lqSmRrcVBIS1M2S0dsTDgrT3BZeGRK?=
 =?utf-8?B?SkdabGhMM2RxZHpheW5MR3YvVHdRS01FR1J4cTNYb3VIVmRJWnhVMjdURzhZ?=
 =?utf-8?B?eW1qZ0h6UnRQb3dKNjlIVWlmSWFJUll0VS9SUFRxdnR2WUtsTkhFeXdCSm5J?=
 =?utf-8?B?MzI0U0VNcTNaQWhrOW9vLzdxWWpXSTJPTmIzQWhGVjJnQ1pmWElmRlpEckdN?=
 =?utf-8?Q?bQqDOOXnc1qLg60VFNQU9wC6f?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 76e5ff95-15b4-4496-518c-08da9bbd9189
X-MS-Exchange-CrossTenant-AuthSource: SN1PR12MB2381.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Sep 2022 10:39:32.2916
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: 7+xBE/gDJ3SwkkMhL/sY9vgKbohb8sZR7xnJ3/GDXuYL79UrDmYpZGAXC7P9vIpLfvzkDVmTa3FCcXxrpNSWsw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB7135
X-Spam-Status: No, score=-5.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

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