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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 52DEEC3279B for ; Wed, 4 Jul 2018 15:00:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A2B7208B6 for ; Wed, 4 Jul 2018 15:00:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A2B7208B6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752571AbeGDPAQ (ORCPT ); Wed, 4 Jul 2018 11:00:16 -0400 Received: from foss.arm.com ([217.140.101.70]:38938 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752114AbeGDPAP (ORCPT ); Wed, 4 Jul 2018 11:00:15 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A8F8B18A; Wed, 4 Jul 2018 08:00:14 -0700 (PDT) Received: from [10.1.206.53] (e108454-lin.cambridge.arm.com [10.1.206.53]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 955463F5A0; Wed, 4 Jul 2018 08:00:12 -0700 (PDT) Subject: Re: [kvmtool test PATCH 22/24] kvmtool: arm64: Add support for guest physical address size To: Will Deacon , Suzuki K Poulose Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, marc.zyngier@arm.com, cdall@kernel.org, eric.auger@redhat.com, catalin.marinas@arm.com, punit.agrawal@arm.com, qemu-devel@nongnu.org References: <1530270944-11351-1-git-send-email-suzuki.poulose@arm.com> <1530270944-11351-23-git-send-email-suzuki.poulose@arm.com> <20180704140943.GF4828@arm.com> From: Julien Grall Message-ID: <8c9bb3cd-f673-17f3-656f-66b7e14fc73c@arm.com> Date: Wed, 4 Jul 2018 16:00:11 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180704140943.GF4828@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 04/07/18 15:09, Will Deacon wrote: > On Fri, Jun 29, 2018 at 12:15:42PM +0100, Suzuki K Poulose wrote: >> Add an option to specify the physical address size used by this >> VM. >> >> Signed-off-by: Suzuki K Poulose >> --- >> arm/aarch64/include/kvm/kvm-config-arch.h | 5 ++++- >> arm/include/arm-common/kvm-config-arch.h | 1 + >> 2 files changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/arm/aarch64/include/kvm/kvm-config-arch.h b/arm/aarch64/include/kvm/kvm-config-arch.h >> index 04be43d..dabd22c 100644 >> --- a/arm/aarch64/include/kvm/kvm-config-arch.h >> +++ b/arm/aarch64/include/kvm/kvm-config-arch.h >> @@ -8,7 +8,10 @@ >> "Create PMUv3 device"), \ >> OPT_U64('\0', "kaslr-seed", &(cfg)->kaslr_seed, \ >> "Specify random seed for Kernel Address Space " \ >> - "Layout Randomization (KASLR)"), >> + "Layout Randomization (KASLR)"), \ >> + OPT_INTEGER('\0', "phys-shift", &(cfg)->phys_shift, \ >> + "Specify maximum physical address size (not " \ >> + "the amount of memory)"), > > Given that this is a shift value, I think the help message could be more > informative. Something like: > > "Specify maximum number of bits in a guest physical address" > > I think I'd actually leave out any mention of memory, because this does > actually have an effect on the amount of addressable memory in a way that I > don't think we want to describe in half of a usage message line :) Is there any particular reasons to expose this option to the user? I have recently sent a series to allow the user to specify the position of the RAM [1]. With that series in mind, I think the user would not really need to specify the maximum physical shift. Instead we could automatically find it. Cheers, [1] http://archive.armlinux.org.uk/lurker/message/20180510.140428.1c295b5b.en.html > > Will > -- Julien Grall