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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9B35FE77188 for ; Wed, 8 Jan 2025 23:08:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vgCJheOFNNrmteKZk0wzRAtFXLDsAQbokdoxMYfFalE=; b=ODE0WV+6I/69B7hqhiOUFh5JIT OfkxEJAJnXUt/9jtHRl4XvLzYeQ+DM1RsiA6MToXYUdVuQA9QdANixL1ALZ8yHF3DrC2CvD8PMEQT f2564cbqOWtNO/h+6XIzgQD3WsIQ9900HazsW4a7X7Tj5Vd34leBAcckOwT5WW7wE84RVQNgEldPN X4vcDZqYXmQ2qpdt8DJc9m2Q6Tg6cCqeomF8WYzdzEMQMUAt+k5Qb01/wUpZ5A7h6vc0Xza9x1hhx 0Z3p05cr85dSlXG9Fc7/oAVXXVtVBbzsafdNId96i9za5Lg6fii6R3BBTz4KlLvoBYjfH4wu7GZ7E 04LIjswg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVf9x-0000000A7TA-1DH4; Wed, 08 Jan 2025 23:08:21 +0000 Received: from out-174.mta0.migadu.com ([2001:41d0:1004:224b::ae]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tVf8j-0000000A79v-1yOb for linux-arm-kernel@lists.infradead.org; Wed, 08 Jan 2025 23:07:06 +0000 Date: Wed, 8 Jan 2025 15:06:10 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1736377576; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=vgCJheOFNNrmteKZk0wzRAtFXLDsAQbokdoxMYfFalE=; b=RoyE56dLBW3iwVFoe4/0jZuzFyNsE0AxyizsfrjApzlczaZ9iaQ4zVx1/j57m6P4c40Rgt C0rqUt+JRAMyK+uPEa6hg80NmzL/6IKYbtL95Hp9W+DU+SpiNvVt44EEujX4Tgfj4NnJiY 01nr+YtvrbmxnICjtMV21yHlwbga2oo= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Marc Zyngier Cc: Will Deacon , kvmarm@lists.linux.dev, Joey Gouly , Suzuki K Poulose , Zenghui Yu , Mingwei Zhang , Colton Lewis , Raghavendra Rao Ananta , Catalin Marinas , Mark Rutland , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 00/18] KVM: arm64: Support FEAT_PMUv3 on Apple hardware\ Message-ID: References: <20241217212048.3709204-1-oliver.upton@linux.dev> <20250108123840.GA9197@willie-the-truck> <87jzb5q9nl.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87jzb5q9nl.wl-maz@kernel.org> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250108_150705_650547_DD67FD17 X-CRM114-Status: GOOD ( 20.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jan 08, 2025 at 09:26:54PM +0000, Marc Zyngier wrote: > On Wed, 08 Jan 2025 20:14:07 +0000, > Oliver Upton wrote: > > > > Hey Will, > > > > On Wed, Jan 08, 2025 at 12:38:41PM +0000, Will Deacon wrote: > > > What's your plan for this series? I started looking at it and I can take > > > the first four apple_m1 patches if you like? > > > > I plan on posting a respin of it by next week, which should look pretty > > much the same besides cleaning up the build error I introduced :) > > > > Besides that, I think we need to decide on the KVM side of things > > whether or not we want to support an event counter in addition to the > > PMU cycle counter. Janne's FEX use case would certainly benefit from it. > > I think we should always be able to support *one* counter on top of > the cycle counter. Doing more than that would result in inconsistent > behaviours (some events only count on a single counter). > > Unless we restrict ourselves to a very small set of events that we can > always schedule on any counter, but this doesn't sound very promising. I definitely agree that a single event counter is the way to go. Dealing with this IMPDEF crud is gross already, and coping with event affinities would only make it worse. I was more wanting to test the idea that we want programmable event counters at all, although it isn't that much of a burden on top of the cycle counter. I'll un-RFC the tail of the series in v2 then. -- Thanks, Oliver