From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-184.mta1.migadu.com (out-184.mta1.migadu.com [95.215.58.184]) (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 3F3311DFD84 for ; Tue, 3 Dec 2024 22:32:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.184 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733265172; cv=none; b=WjEuqhHi6E3q0KlxLmGwpjMTSKkAPjrdyafmf+92n2qbfaBTcmfBiCmYnICQ7GS1EJgVWS/EP/t0nwkICWzXCXdMhbljM/XrgV2gbo8HnBPgl4irdsg3uBR371qvl+/NS4JmKsvIJyb+WSXDgYcTyqYJhE5fYD9wT4wSzTuFhS8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733265172; c=relaxed/simple; bh=5xMXuje2rUezOB3vk/lCC+YV5xNh0tfH3rMlg84BM68=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MOriIiw8Tg8AZWbUQ+kICkWHC+VZVLPn39QC6K6y+kbH6QPVaBeW1ywQY6x5vqH3LNw4QbhXY2aNuPRFIIgGlPJmOQp+7g11ks/A82dEFEbWC7OKMPddaidM8d9f/LoDTQYUKXSMsHskx8GOFZTKiTG59+bzMy7ljbx3sbktToQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=lKeUpq1H; arc=none smtp.client-ip=95.215.58.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="lKeUpq1H" Date: Tue, 3 Dec 2024 14:32:38 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1733265168; 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=hW6mNNVP48/Mj7mfy3CFRZP/i3VCK2OWGnyJMzSgKV8=; b=lKeUpq1HixcYGhKHPIjBx5QNSGodFFQIQucOMLyelNmPqr3SCb6YdppIiid4Fl1hXAcTEX paJ1KXPjqk2uMXzF/3ifnchnBBeUQUhezqTLsRyfaCJIEhd+DDnQOw8HBeLP7nZTCdH73E mxQwVWdcMoCujqQhOH+fthdwYpPQL5k= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Marc Zyngier 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 Message-ID: References: <20241203193220.1070811-1-oliver.upton@linux.dev> <20241203193220.1070811-6-oliver.upton@linux.dev> <87ldwwsbad.wl-maz@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ldwwsbad.wl-maz@kernel.org> X-Migadu-Flow: FLOW_OUT On Tue, Dec 03, 2024 at 09:32:10PM +0000, Marc Zyngier wrote: > 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. Yeah... A bit of a dirty shortcut I took because I don't like the ABI, but distaste isn't enough to break it :) > 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. Yeah, that sounds reasonable. Especially if we allow programmable event counters where the event ID space doesn't match the architecture. -- Thanks, Oliver