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 D368DC7618D for ; Thu, 6 Apr 2023 16:09:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239891AbjDFQJB (ORCPT ); Thu, 6 Apr 2023 12:09:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49356 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239687AbjDFQJA (ORCPT ); Thu, 6 Apr 2023 12:09:00 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4E48AD2A for ; Thu, 6 Apr 2023 09:08:35 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-54bfe7a161eso43034447b3.8 for ; Thu, 06 Apr 2023 09:08:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680797315; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=JYDmhXi/TjFwHMmzA8N0vuTfzAZMCED+yyDglZvkbXU=; b=KCEfdgD9PzOOYg+KvucgqQrQE1hNaq/3VolOyaJJyZ4TXDo0pzMnDJ6L0fiXzXU4c5 AabzTTX931ruQLDUIfjr+miI4EfyKvittVJVcvTaFKM3jn20r41MG3qt/CVeB+iSB2m1 FNKo+Fwii5R8zOE2ycvd3DZH2TY5sBz4pYJg9YC5Qafe1nJLjhWEo3gSjt4Ly2ayYBOv z4oXzJJlu81bGcabjFWON9+GFMttEQ398tfN9N9rBo0LgA/5S6kHOY6ugcfVUUiIW7gG 83vNktHVX8vDk6w7C5Dyhxew92/Y30LLmdHiYCNuUubULBevhi9YlnNDUIukMBO1xYfN kBMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680797315; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=JYDmhXi/TjFwHMmzA8N0vuTfzAZMCED+yyDglZvkbXU=; b=G0SYjxeo3DNRWeWV8j+y6/nLT8dJ9N0jJdG5ST+E9mO66MvdUxWzZCTlUSWaqcPfbn m0fYtHj4N7H71XpeuytBJ++5ePs9fSWe/u5rnurckEKVWLCzyS2TeFDFSB1ePgyjKSrf ApqyQilA4j33TvZYfjDE3AoIxTH4g6QZHAkySy9LjOOMYvwJ3ikCD7AaVIESRIybBYG3 l4lvzpEy6AWMns7U0uOciobXclmtraaakP7VV9PJKqsm89PWvtOaZXhCpEFMvepmWTQ+ n1SMPlgOCBYknscGwf0Jjr1StdHnsGVx1TLzvmAzi9dkl5ZofSOIvs+UTXTTopgmip3S SjHw== X-Gm-Message-State: AAQBX9cBAa9BI++/TDRZrNpL+jo1m/ivJ53/SVe8ccgEBrwPX0byO6/y mZk1C44Z957vZBnhA+FyWcVfAnxG7+E= X-Google-Smtp-Source: AKy350ZEYpasxDWhqFvJ/5zzOHtQu4My3fps0PjBEgaIISod28ND+cj65xFgu7Ib1ex6wQUjRtYjtnbKs+U= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:d186:0:b0:b1d:5061:98e3 with SMTP id i128-20020a25d186000000b00b1d506198e3mr2363694ybg.6.1680797314872; Thu, 06 Apr 2023 09:08:34 -0700 (PDT) Date: Thu, 6 Apr 2023 09:08:33 -0700 In-Reply-To: <20230406095711.GH386572@hirez.programming.kicks-ass.net> Mime-Version: 1.0 References: <1680766393-46220-1-git-send-email-lirongqing@baidu.com> <20230406095711.GH386572@hirez.programming.kicks-ass.net> Message-ID: Subject: Re: [PATCH][v2] x86/kvm: Don't check vCPU preempted if vCPU has dedicated pCPU and non-trap HLT From: Sean Christopherson To: Peter Zijlstra Cc: lirongqing@baidu.com, pbonzini@redhat.com, wanpengli@tencent.com, vkuznets@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, kvm@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Apr 06, 2023, Peter Zijlstra wrote: > On Thu, Apr 06, 2023 at 03:33:13PM +0800, lirongqing@baidu.com wrote: > > From: Li RongQing > > > > Check whether vCPU is preempted or not only when HLT is trapped or > > there is not realtime hint. In other words, it is unnecessary to check > > preemption when vCPU has realtime hint (which means vCPU has dedicated > > pCP) and has not PV_UNHALT (which means unintercepted HLT), because > > vCPU should not to be marked as preempted in this setup. > > To what benefit? > > > Signed-off-by: Li RongQing > > --- > > diff with v1: rewrite changelog and indentation This also fails to mention my objection to querying PV_UNHALT[*]. When I said "this needs Paolo's attention no matter what", I did not mean "post a v2 and hope Paolo applies it", I meant we need Paolo (and others) to weigh in on the ongoing discussion. [*] https://lore.kernel.org/all/ZBEOK6ws9wGqof3O@google.com