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[23.128.96.18]) by mx.google.com with ESMTP id nc38si8917889ejc.386.2021.05.14.19.26.06; Fri, 14 May 2021 19:26:30 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=u3bueLRy; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231580AbhENVWT (ORCPT + 99 others); Fri, 14 May 2021 17:22:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231182AbhENVWS (ORCPT ); Fri, 14 May 2021 17:22:18 -0400 Received: from mail-lf1-x133.google.com (mail-lf1-x133.google.com [IPv6:2a00:1450:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C575FC06174A for ; Fri, 14 May 2021 14:21:06 -0700 (PDT) Received: by mail-lf1-x133.google.com with SMTP id g4so298531lfv.6 for ; Fri, 14 May 2021 14:21:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=kr02OQRBAUClRPq6pzrHz4TBil6QdXjMy0YYb2MF1hc=; b=u3bueLRypu0wYM/PhDv20UOfoUyiLMETf/vvFMNUaUk7+ikcvONEeot78kI4vIcgQK v95kfpcuOMDQPmEBX77HwcegX89WUhvjDorNrOMsshReuLuvB07C7rHjSxl0oEbfo0S6 b3WrxZ79v1ZpR2F0qTyMCagCNkLaoRjJ1Sd3Yn2BKNRPERXG9AodbYO1QPp6YejU/nVW TCHaC5d2FbISKcjym65yLRSRxKsLISaruSW+fvVOq0AubfZ38Tr3Ulrv1YXJ22+ISo/9 Qc9IAu9Kdgq6u2rTlWoEEV8a3UaWg/nxF6h0/XjIcbKplDHN5pYR2t5iSTjqcpbKSwlk XKlw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=kr02OQRBAUClRPq6pzrHz4TBil6QdXjMy0YYb2MF1hc=; b=Tir7AipE/bs4vGnlxWejI1XeIBjhnvfJO7vKyLC8KSsiIKkkQii9EYFhpl2hjwoH/3 t1CW2+wVNRqTjcFWUFdN6tBQbIj5/Rg/caqmq/go94QEwSuQihbVgGn600byNumKpqO0 Zc2A0vX9Vyg04PpQhsZvYqCWE9Dz0Gxm0B7llQFnc/qRTZ8Z4uXXeZUHXnCL/YXQhPNH DYBWZAumotlAzBStvGQiXn8knDP9io1URtFqBndLg2FQ2yUgYo2efhGwJlcol3BLZZFA VR79g6GPL9lF08T8gNC8yT6PpGwpInEayJk+g1cTh85/dUtdCM8frBu/QFS22KTBcQgC 8NIQ== X-Gm-Message-State: AOAM532DjF550TCgJFADAph+2eyEqm+KAFnx1TtjAmMxkJo7KiJBeyiZ Kt+RkH3F0Bv0+hmuDP0iNoSezO2CtTgR91vMoLeZQw== X-Received: by 2002:a05:6512:acc:: with SMTP id n12mr34825576lfu.9.1621027265153; Fri, 14 May 2021 14:21:05 -0700 (PDT) MIME-Version: 1.0 References: <1620871084-4639-1-git-send-email-wanpengli@tencent.com> In-Reply-To: <1620871084-4639-1-git-send-email-wanpengli@tencent.com> From: David Matlack Date: Fri, 14 May 2021 14:20:38 -0700 Message-ID: Subject: Re: [PATCH v2 1/4] KVM: PPC: Book3S HV: exit halt polling on need_resched() as well To: Wanpeng Li Cc: linux-kernel@vger.kernel.org, kvm list , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Ben Segall , Venkatesh Srinivas , Paul Mackerras , Suraj Jitindar Singh Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 12, 2021 at 6:58 PM Wanpeng Li wrote: > > From: Wanpeng Li > > Inspired by commit 262de4102c7bb8 (kvm: exit halt polling on need_resched() > as well), CFS_BANDWIDTH throttling will use resched_task() when there is just > one task to get the task to block. It was likely allowing VMs to overrun their > quota when halt polling. Due to PPC implements an arch specific halt polling > logic, we should add the need_resched() checking there as well. > > Cc: Ben Segall > Cc: Venkatesh Srinivas > Cc: Jim Mattson > Cc: David Matlack > Cc: Paul Mackerras > Cc: Suraj Jitindar Singh > Signed-off-by: Wanpeng Li > --- > v1 -> v2: > * update patch description > > arch/powerpc/kvm/book3s_hv.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 28a80d2..6199397 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -3936,7 +3936,8 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc) > break; > } > cur = ktime_get(); > - } while (single_task_running() && ktime_before(cur, stop)); > + } while (single_task_running() && !need_resched() && > + ktime_before(cur, stop)); Consider moving this condition to a helper function that can be shared between book3s and the generic halt-polling loop. > > spin_lock(&vc->lock); > vc->vcore_state = VCORE_INACTIVE; > -- > 2.7.4 >