From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BEC8A1885A0; Tue, 3 Dec 2024 21:32:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733261533; cv=none; b=IZy9mcxu75XZIMMWzrQq/bIl7awb9DTpCZ7DuH9TTJ/svDAqHEW42CG5Eg4SftYwhIEPn83I7ChVNTydJQhDlQA5apft2tNPwuha7HzESgkdCeI6Sfooa8nWVb7ZivzqJ+K2Atpou5ks+1zczv8BP5NXgm7PG1cyN90tdQsrGYI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733261533; c=relaxed/simple; bh=BOg48Ob9/NVzqkpxLrxQQVqMKoA0kVXfOH8VOSVCmp0=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=iqDsZW5+WdZ/qxBIWdBLTDTLZlxGeR2rYcKQ/lum2IYZndIXxHdu8X3xVvOBDka/xOrPBVbAbtAkGiCiIL4UiFB8lkt7pvob04ip9IoBTzZY/cOeRCip7ar9G7PYj9qNS2vrMrRXTuLLUKMOSFeiYh7LHqK7wUHrwb4qrzsA6K0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BQChVggg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BQChVggg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 498E7C4CED8; Tue, 3 Dec 2024 21:32:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733261533; bh=BOg48Ob9/NVzqkpxLrxQQVqMKoA0kVXfOH8VOSVCmp0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=BQChVgggT/bBeKHZ8u8dvoyJoHoBlz9+KD0dYqf7fyD45vOJGfMo0S7WkoUP8Vl8W ziJNnSxLXVJr/YwOo9BOglDutV4ejT1qz/qCrjysPT8FVGB0njHXQhhtUYqqeQV97a YX11HDV2c3KepOLCh5LoNsW7yCk/TZ15gxW/5oSZA/ZhSlhz/Va04JD2xEP1vYZHWI +3hv13473VvVtkKiuBdK8C8Afo167/LLjFPjfgfoGeD297Jc7mNlOn+H6btyGm4D9j 9JSxRiQPjgv92f7BZlzDKxyYk3QGZtYgrxJ7kGToFqQKaJVH9zGTsPrcmBXt7WJ0rU emXujeUxfEE5Q== Received: from sofa.misterjones.org ([185.219.108.64] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1tIaV8-000EuJ-Rd; Tue, 03 Dec 2024 21:32:10 +0000 Date: Tue, 03 Dec 2024 21:32:10 +0000 Message-ID: <87ldwwsbad.wl-maz@kernel.org> From: Marc Zyngier To: Oliver Upton Cc: kvmarm@lists.linux.dev, Joey Gouly , Suzuki K Poulose , Zenghui Yu , Mingwei Zhang , Colton Lewis , Raghavendra Rao Ananta , Catalin Marinas , Will Deacon , Mark Rutland , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 05/14] KVM: arm64: Always allow fixed cycle counter In-Reply-To: <20241203193220.1070811-6-oliver.upton@linux.dev> References: <20241203193220.1070811-1-oliver.upton@linux.dev> <20241203193220.1070811-6-oliver.upton@linux.dev> 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/29.4 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: oliver.upton@linux.dev, kvmarm@lists.linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, mizhang@google.com, coltonlewis@google.com, rananta@google.com, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Tue, 03 Dec 2024 19:32:11 +0000, Oliver Upton wrote: > > The fixed CPU cycle counter is mandatory for PMUv3, so it doesn't make a > lot of sense allowing userspace to filter it. Only apply the PMU event > filter to *programmed* event counters. But that's a change in ABI, isn't it? We explicitly say in the documentation that the cycle counter can be filtered by specifying event 0x11. More importantly, the current filtering works in terms of events, and not in terms of counters. Instead of changing the ABI, how about simply not supporting filtering on such non-compliant HW? Surely that would simplify a few things. Thanks, M. -- Without deviation from the norm, progress is not possible.