From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC055C433E5 for ; Wed, 24 Mar 2021 11:28:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A22D461A18 for ; Wed, 24 Mar 2021 11:28:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232642AbhCXL22 (ORCPT ); Wed, 24 Mar 2021 07:28:28 -0400 Received: from mail-wr1-f44.google.com ([209.85.221.44]:45039 "EHLO mail-wr1-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232541AbhCXL2N (ORCPT ); Wed, 24 Mar 2021 07:28:13 -0400 Received: by mail-wr1-f44.google.com with SMTP id c8so11156790wrq.11; Wed, 24 Mar 2021 04:28:12 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=KU6Dop6apks1kihX2YOTKvNWDKeXQ1Kugy0fdGkesUo=; b=RQlvlYRLezr7U+O3czo3zDVKnUtg4dbCrFfTf/LVt+gI+FVrrjAxAzulBGkkFzOUi0 baCcPYu7KluymLwAWdVNOI23Qg4dcKigb3yv7tzUY4Wm4CEhg9HIU5NQknbUmNf9TSUA gvtMRoUdW9Mz0gzRmwC1kLNCWdEp2ba0xlglMAytPY60QypPyrqN0E9vkiM7US562gEh fj+/Yk/EKasXK5H/jp1w8H/1IMCM6n5bGbT0795rHJxcyDH9ru9ATGxdhM1RNee9p5Nb A/QIwGMpaOVyF17WHRUix//DREIkFuYWqdT9fHsDMkVo4+ViZP2bLQrpxKJ5cQb/fM/8 dtWg== X-Gm-Message-State: AOAM532m51B2eZKiUD3IDoGJUs1yuzwlTxoBgVLFzvUnE0+36ivg7mDG uGSrNYO+kCGP7AYxgWv7i4c= X-Google-Smtp-Source: ABdhPJyprfHTGT03IVPxhkqw3jBH7YUkK5fWR9U6uwyBT311htVyjfE/HL884+ZtcLB4mkY4Yyl+6g== X-Received: by 2002:a5d:4fca:: with SMTP id h10mr3140552wrw.70.1616585291877; Wed, 24 Mar 2021 04:28:11 -0700 (PDT) Received: from liuwe-devbox-debian-v2 ([51.145.34.42]) by smtp.gmail.com with ESMTPSA id i16sm4663531wmq.3.2021.03.24.04.28.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Mar 2021 04:28:11 -0700 (PDT) Date: Wed, 24 Mar 2021 11:28:10 +0000 From: Wei Liu To: Xu Yihang Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, johnny.chenyi@huawei.com, heying24@huawei.com, Wei Liu Subject: Re: [PATCH -next] x86: Fix unused variable 'msr_val' warning Message-ID: <20210324112810.lkeu3ffv6dv7fbab@liuwe-devbox-debian-v2> References: <20210322031713.23853-1-xuyihang@huawei.com> <20210323024302.174434-1-xuyihang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210323024302.174434-1-xuyihang@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 23, 2021 at 10:43:02AM +0800, Xu Yihang wrote: > Fixes the following W=1 kernel build warning(s): > arch/x86/hyperv/hv_spinlock.c:28:16: warning: variable ‘msr_val’ set but not used [-Wunused-but-set-variable] > unsigned long msr_val; > > As Hypervisor Top-Level Functional Specification states in chapter 7.5 Virtual Processor Idle Sleep State, "A partition which possesses the AccessGuestIdleMsr privilege (refer to section 4.2.2) may trigger entry into the virtual processor idle sleep state through a read to the hypervisor-defined MSR HV_X64_MSR_GUEST_IDLE". That means only a read is necessary, msr_val is not uesed, so potentially cast to void in order to silent this warning. > > Reference: > https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs > > Reported-by: Hulk Robot > Signed-off-by: Xu Yihang Applied to hyperv-next. Thanks.