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=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 88678C48BE5 for ; Wed, 16 Jun 2021 11:03:20 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 02043610A3 for ; Wed, 16 Jun 2021 11:03:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02043610A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 7FE1B4A523; Wed, 16 Jun 2021 07:03:19 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id TUD-WBYcT1So; Wed, 16 Jun 2021 07:03:17 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9A5854B091; Wed, 16 Jun 2021 07:03:17 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 1C0164A523 for ; Wed, 16 Jun 2021 07:03:16 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id F6SyN37bncsd for ; Wed, 16 Jun 2021 07:03:14 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id D59B34A4A3 for ; Wed, 16 Jun 2021 07:03:14 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E1F26610A3; Wed, 16 Jun 2021 11:03:13 +0000 (UTC) Received: from [185.219.108.64] (helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1ltTKA-007vgz-En; Wed, 16 Jun 2021 12:03:11 +0100 Date: Wed, 16 Jun 2021 12:03:08 +0100 Message-ID: <87k0mum5qr.wl-maz@kernel.org> From: Marc Zyngier To: Aman Priyadarshi Subject: Re: KVM: arm64: pmu: Reset sample period on overflow handling In-Reply-To: <094d40a0e7f5389ce5a13d96b96d4b7588c71d74.camel@amazon.de> References: <322843db2f986f418d4175ca9c10e0904aa81d7a.camel@amazon.de> <87lf7bhxcf.wl-maz@kernel.org> <131663dbe335646ac952c55d6271022a42fa382f.camel@amazon.de> <87lf7am77t.wl-maz@kernel.org> <094d40a0e7f5389ce5a13d96b96d4b7588c71d74.camel@amazon.de> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: apeureka@amazon.de, kvmarm@lists.cs.columbia.edu, graf@amazon.com, alisaidi@amazon.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: Alexander Graf , kvmarm@lists.cs.columbia.edu, Ali Saidi X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Wed, 16 Jun 2021 11:52:42 +0100, Aman Priyadarshi wrote: > > On Wed, 2021-06-16 at 11:31 +0100, Marc Zyngier wrote: > > > > Hi Aman, > > > > On Wed, 16 Jun 2021 10:17:28 +0100, > > Aman Priyadarshi wrote: > > > > > > Hi Marc, > > > > > > On Tue, 2021-06-15 at 18:05 +0100, Marc Zyngier wrote: > > > > > > > > Can you reproduce the issue with vanilla guest kernels? It'd be > > > > interesting to understand what makes it work on the guest side. Can > > > > you please bisect it? > > > > > > > > > > yes, I was able to narrow it down to the commit 0cbb058be904 ("arm64: > > > perf: > > > Disable PMU while processing counter overflows"), which fixes the > > > problem > > > on the guest side. > > > > Which is 3cce50dfec4a5b0414c974190940f47dd32c6dee in mainline. This > > doesn't seem to have ever been backported before 4.18. So I don't know > > why your 4.15 kernel was correctly behaving, but it could be that the > > distro had randomly picked up the correct patch! > > Yes. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1836117 Right. I guess that's their "value add". > > You may want to backport it to 4.14.y and let Greg know about that. > > > > Ack. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm