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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 27153ECDE27 for ; Wed, 11 Sep 2019 09:21:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EED7D21928 for ; Wed, 11 Sep 2019 09:21:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727299AbfIKJVY (ORCPT ); Wed, 11 Sep 2019 05:21:24 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:2212 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726579AbfIKJVY (ORCPT ); Wed, 11 Sep 2019 05:21:24 -0400 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id E6267DBB613FD0A61D59; Wed, 11 Sep 2019 17:21:21 +0800 (CST) Received: from [127.0.0.1] (10.184.12.158) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.439.0; Wed, 11 Sep 2019 17:21:13 +0800 Subject: Re: [PATCH 2/2] KVM: arm/arm64: Print the EC hex value with its exact width To: Marc Zyngier CC: , , , , , , References: <1568169216-12632-1-git-send-email-yuzenghui@huawei.com> <1568169216-12632-3-git-send-email-yuzenghui@huawei.com> <86h85js083.wl-maz@kernel.org> From: Zenghui Yu Message-ID: Date: Wed, 11 Sep 2019 17:19:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:64.0) Gecko/20100101 Thunderbird/64.0 MIME-Version: 1.0 In-Reply-To: <86h85js083.wl-maz@kernel.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.184.12.158] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, On 2019/9/11 16:31, Marc Zyngier wrote: > On Wed, 11 Sep 2019 03:33:36 +0100, > Zenghui Yu wrote: >> >> EC is the bits [31:26] of ESR_ELx on arm64 (HSR on arm). Print the >> hex value with its exact width (8). >> >> Signed-off-by: Zenghui Yu >> --- >> virt/kvm/arm/trace.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/virt/kvm/arm/trace.h b/virt/kvm/arm/trace.h >> index 204d210d01c2..022b0a060034 100644 >> --- a/virt/kvm/arm/trace.h >> +++ b/virt/kvm/arm/trace.h >> @@ -42,7 +42,7 @@ TRACE_EVENT(kvm_exit, >> __entry->vcpu_pc = vcpu_pc; >> ), >> >> - TP_printk("%s: HSR_EC: 0x%04x (%s), PC: 0x%08lx", >> + TP_printk("%s: HSR_EC: 0x%02x (%s), PC: 0x%08lx", >> __print_symbolic(__entry->ret, kvm_arm_exception_type), >> __entry->esr_ec, >> __print_symbolic(__entry->esr_ec, kvm_arm_exception_class), > > Although you're right that 8 bits ought to be enough, this is a change > to the output of the tracepoint, which userspace could (does?) parse. Well-written userspace tools should only parse the low 8 bits (if they do parse). But even if the high bits are parsed, they're always 0. So I don't think this change will have a bad impact on userspace. > I'm thus reluctant to change anything there, knowing that we don't > lose any information, and just print two extra zeroes. Anyway this is not a fix, feel free to ignore it if you're worried about that there might be some issues ;) > Am I missing anything? No. Thanks, zenghui