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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29557C636D4 for ; Mon, 13 Feb 2023 16:13:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230040AbjBMQNo (ORCPT ); Mon, 13 Feb 2023 11:13:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229947AbjBMQNk (ORCPT ); Mon, 13 Feb 2023 11:13:40 -0500 Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 443711CF6B for ; Mon, 13 Feb 2023 08:13:32 -0800 (PST) Received: by mail-pl1-x62f.google.com with SMTP id h4so6143917pll.9 for ; Mon, 13 Feb 2023 08:13:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=FLmWkbZ6W8xK93xqtmOh8udk6K0hgPNMyGvF9HpUGfU=; b=ZlJP0CXIrViYhrOFoUe8xuxJbCEt1fD2D0ag1jFg9EH9IhedaSsCk+wuNH1cPGpUqw GqtxmbBVvTjiCldKXMRMytdxAr9C8SRJVZZcN5TNRsyrZfYH06BUi0abP+lDKyi7Sgh5 TxBgdwAlw5pUkzGaAGO97t7MWGoj4VU2+y6G6oj4Cz55OG8QmjbWeVUUe+bPTxRi1qgp mRnpsN7/rkRP17Fmy8whdl0DvjBJcCVweRwWBtjxK7oAsXeYXED+tWs66vosozXFdzgD Mlgh1+D3hU9RH0BeIJEw6bDxhJ9j1JBouexdQGCGix99q9Ea1q7J+ivvXLgnagXpaSKV bHWw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=FLmWkbZ6W8xK93xqtmOh8udk6K0hgPNMyGvF9HpUGfU=; b=w9p3jQtWn33xPIre5TQ8dCXTefgK2w1OwMB9ehvQ/G+tIr10zaK6ij0JcOJp2E/nSX fw9xO2YFAZHpQNFBbuHCwgZgmu8JplAn2K+ydfGtaGocze0bJRVgibbW6nLI6BVTReH/ elnMRs6BvIc5BXT7IozOH07M8jXA7GXtd8Z8BhRtM3rf2+PyIF/7K+witq2yKFp7aOKW 2f1Jq73HxUxPqbiLw18Ds4yUCo7eens5Aq3MbOqWLq6r05LMwBE97/yNS0G7LAecUvfE QhUOE71a5Gl3wgB02E3yeCWgtgpVGN5DSSxLJHU/OBHtmfeyDCcYN/+L3ahvAcGF/A6R whLQ== X-Gm-Message-State: AO0yUKV1rIj3enxYWcrcmiMK4TD3/HbYGxkdNIupoCCL9BMZhjsEJlxN X9pk3ZyS0dA2Ys0FXkpvVPwnsQ== X-Google-Smtp-Source: AK7set/I5nfPc3xL9FZQVQvjiiiD5NXupUx+Nqg2zvw8k3DSFQd6yGY6CYyWNbhl6VXjNSAEY+QrPw== X-Received: by 2002:a17:902:e354:b0:198:af50:e4df with SMTP id p20-20020a170902e35400b00198af50e4dfmr440640plc.5.1676304811530; Mon, 13 Feb 2023 08:13:31 -0800 (PST) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id e8-20020aa78c48000000b005a8a894ca96sm3393179pfd.64.2023.02.13.08.13.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Feb 2023 08:13:31 -0800 (PST) Date: Mon, 13 Feb 2023 16:13:27 +0000 From: Sean Christopherson To: lirongqing@baidu.com Cc: pbonzini@redhat.com, wanpengli@tencent.com, vkuznets@redhat.com, tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH] x86/kvm: Don't use PVspinlock when mwait is advertised Message-ID: References: <1676124399-16542-1-git-send-email-lirongqing@baidu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1676124399-16542-1-git-send-email-lirongqing@baidu.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Sat, Feb 11, 2023, lirongqing@baidu.com wrote: > From: Li RongQing > > MWAIT is advertised in host is not overcommitted scenario, however, > pvspinlock should be enabled in host overcommitted scenario. Let's > add the MWAIT checking when enabling pvspinlock > > Signed-off-by: Li RongQing > --- > arch/x86/kernel/kvm.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index 1cceac5..dfa1451 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -1087,6 +1087,11 @@ void __init kvm_spinlock_init(void) > goto out; > } > > + if (boot_cpu_has(X86_FEATURE_MWAIT)) { IMO this is a bad idea. Odds are good that there are less-than-perfect VM configs that advertise MONITOR+MWAIT but don't disable interception. Ugh, but we've already added this logic for other features guaraded by KVM_HINTS_REALTIME in commit 40cd58dbf121 ("x86/kvm: Don't use PV TLB/yield when mwait is advertised") Why doesn't the host simply advertise KVM_HINTS_REALTIME?