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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 D387FC352A3 for ; Mon, 10 Feb 2020 15:46:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA7AB2082F for ; Mon, 10 Feb 2020 15:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581349576; bh=TTGiUvb9RHz3hdhmJfOzp0KIapqFPLU42O9zSWvHhOE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=thI+R3cwrrLkmmd9m6f/86HEHqwvIt+LVLu5919OnG7LWzwtAeA78n2vokUY0YkjS QhcXK1w6FjlM0pN+d9zEl1yHEm2CI7mkWOce82GfnXxRFwv8ECXxHyG0WOwijyzgHH /loa+/Zn6ripIQXOF33K+tggN7XZQkPZcGNUrnug= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727613AbgBJPqP (ORCPT ); Mon, 10 Feb 2020 10:46:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:49528 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726991AbgBJPqP (ORCPT ); Mon, 10 Feb 2020 10:46:15 -0500 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (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 53B6620733; Mon, 10 Feb 2020 15:46:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581349574; bh=TTGiUvb9RHz3hdhmJfOzp0KIapqFPLU42O9zSWvHhOE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Nbgh66A2RBEWvXx6MerEIUd9giZyvTUtyT0g89HKzIxi8UAO5FFSC3DotkWGBZgWh 8VmqH2A4GRYx8VmqwMzWPYlvCHE9g4TRJiKoqXV66JFgqs70vggQKyGjqiH94fc6A/ x27HEPnRKKPuNUTsEcUCTryiOPmjdOg06CwR+Wdo= Date: Mon, 10 Feb 2020 15:46:08 +0000 From: Will Deacon To: Marc Zyngier Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, James Morse , Julien Thierry , Suzuki K Poulose , Paolo Bonzini , Christoffer Dall , Quentin Perret , Russell King , Vladimir Murzin , Anders Berg , Arnd Bergmann Subject: Re: [RFC PATCH 0/5] Removing support for 32bit KVM/arm host Message-ID: <20200210154608.GA21086@willie-the-truck> References: <20200210141324.21090-1-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200210141324.21090-1-maz@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Feb 10, 2020 at 02:13:19PM +0000, Marc Zyngier wrote: > KVM/arm was merged just over 7 years ago, and has lived a very quiet > life so far. It mostly works if you're prepared to deal with its > limitations, it has been a good prototype for the arm64 version, > but it suffers a few problems: > > - It is incomplete (no debug support, no PMU) > - It hasn't followed any of the architectural evolutions > - It has zero users (I don't count myself here) I tend to use it to test that it still works, but that's it. > - It is more and more getting in the way of new arm64 developments To echo this last point, we're currently looking at the possibility of using KVM to isolate VMs from the host in Android. The scope of the changes we think we'll have to make would mean effectively duplicating the existing code for 32-bit or implementing a whole load of unused and untested functionality to keep the current structure. Neither of these options are particularly satisfactory from a maintainance point of view, so removing the 32-bit code if it doesn't have any significant use would be welcomed: Acked-by: Will Deacon Will