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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 7C6F7C433F5 for ; Thu, 9 Sep 2021 09:20:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 56F9F610FF for ; Thu, 9 Sep 2021 09:20:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232661AbhIIJV2 (ORCPT ); Thu, 9 Sep 2021 05:21:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60182 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232262AbhIIJV0 (ORCPT ); Thu, 9 Sep 2021 05:21:26 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD792C061575 for ; Thu, 9 Sep 2021 02:20:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=IyaHxbHrWHESvHEgCgnS7Dg++IJnYpRzFIhVsk07plM=; b=kQCev6k9EudyOuQUg40ymmqsPM 61OHyrfzV8y/acWXLARd6ZfHFHOSnezuzqF405IrKoeHePEmOlxBLlLiA0r2EtlRhhm67+l+ZoA7i lp3fOpeb4BpA5UdJgsofTvs8idE9erc6ZPd1PFYxlz8sYenKpn6A5tSCIeMHGTUNhj2+wOgyZIDmH WDFYgJi7geDCVrrWORAfx94hfjy5TGxjwPDGxSyXVsc+Iuos0JU370R6ktVj8USFg0MyZMj1EzzBR VyXfOXaO7/W34O2DdvEFS+Rt9P/CGdhvwYHOpcdkRkqpQ5DqIt2AmbXN/gfiG3qgI+Iwd0I/ptseO pQWXQWAQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mOGE4-001pv3-ST; Thu, 09 Sep 2021 09:20:09 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 7BF9F300094; Thu, 9 Sep 2021 11:20:08 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 658742C625917; Thu, 9 Sep 2021 11:20:08 +0200 (CEST) Date: Thu, 9 Sep 2021 11:20:08 +0200 From: Peter Zijlstra To: Stephane Eranian Cc: linux-kernel@vger.kernel.org, acme@redhat.com, jolsa@redhat.com, kim.phillips@amd.com, namhyung@kernel.org, irogers@google.com Subject: Re: [PATCH v1 09/13] perf/x86/amd: add idle hooks for branch sampling Message-ID: References: <20210909075700.4025355-1-eranian@google.com> <20210909075700.4025355-10-eranian@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210909075700.4025355-10-eranian@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 09, 2021 at 12:56:56AM -0700, Stephane Eranian wrote: > On AMD Fam19h Zen3, the branch sampling (BRS) feature must be disabled before entering low power > and re-enabled (if was active) when returning from low power. Otherwise, the NMI interrupt may > be held up for too long and cause problems. Stopping BRS will cause the NMI to be delivered if it > was held up. What you sent me ^^^, vs reflow at 72 chars vvv: On AMD Fam19h Zen3, the branch sampling (BRS) feature must be disabled before entering low power and re-enabled (if was active) when returning from low power. Otherwise, the NMI interrupt may be held up for too long and cause problems. Stopping BRS will cause the NMI to be delivered if it was held up. (because git show has that stupid extra indentation for Changelogs)