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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 5E583C0044C for ; Mon, 5 Nov 2018 13:26:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 133682081D for ; Mon, 5 Nov 2018 13:26:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 133682081D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=hygon.cn 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 S1729693AbeKEWqQ (ORCPT ); Mon, 5 Nov 2018 17:46:16 -0500 Received: from [110.188.70.11] ([110.188.70.11]:10618 "EHLO spam1.hygon.cn" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726723AbeKEWqQ (ORCPT ); Mon, 5 Nov 2018 17:46:16 -0500 Received: from spam1.hygon.cn (localhost [127.0.0.2] (may be forged)) by spam1.hygon.cn with ESMTP id wA5CtGBO096732 for ; Mon, 5 Nov 2018 20:55:16 +0800 (GMT-8) (envelope-from puwen@hygon.cn) Received: from MK-FE.hygon.cn ([172.23.18.61]) by spam1.hygon.cn with ESMTP id wA5CsJ4N096487; Mon, 5 Nov 2018 20:54:19 +0800 (GMT-8) (envelope-from puwen@hygon.cn) Received: from cncheex01.Hygon.cn ([172.23.18.10]) by MK-FE.hygon.cn with ESMTP id wA5CrnOe063640; Mon, 5 Nov 2018 20:53:49 +0800 (GMT-8) (envelope-from puwen@hygon.cn) Received: from pw-vbox.hygon.cn (172.23.18.44) by cncheex01.Hygon.cn (172.23.18.10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1466.3; Mon, 5 Nov 2018 20:54:14 +0800 From: Pu Wen To: , , , , , CC: Pu Wen Subject: [PATCH] x86/cpu: Avoid endless loop to get the number of cache leaves Date: Mon, 5 Nov 2018 20:53:45 +0800 Message-ID: <1541422425-5855-1-git-send-email-puwen@hygon.cn> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [172.23.18.44] X-ClientProxiedBy: cncheex02.Hygon.cn (172.23.18.12) To cncheex01.Hygon.cn (172.23.18.10) X-MAIL: spam1.hygon.cn wA5CsJ4N096487 X-DNSRBL: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org To get the number of cache leaves on AMD or Hygon platform, it should get the value of cpuid leaf 0x8000001d. But on certain broken platform such as a not fullly implemented virtual platform(Xen, for example), the value of the cpuid leaf will nerver be CTYPE_NULL, so the kernel will run into an endless loop. To fix this problem, add a new enum type CTYPE_MAX to limit the maximum cpuid accessing. Signed-off-by: Pu Wen --- arch/x86/kernel/cpu/cacheinfo.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c index dc1b934..7bd167f 100644 --- a/arch/x86/kernel/cpu/cacheinfo.c +++ b/arch/x86/kernel/cpu/cacheinfo.c @@ -121,7 +121,8 @@ enum _cache_type { CTYPE_NULL = 0, CTYPE_DATA = 1, CTYPE_INST = 2, - CTYPE_UNIFIED = 3 + CTYPE_UNIFIED = 3, + CTYPE_MAX = 4 }; union _cpuid4_leaf_eax { @@ -640,7 +641,7 @@ static int find_num_cache_leaves(struct cpuinfo_x86 *c) /* Do cpuid(op) loop to find out num_cache_leaves */ cpuid_count(op, i, &eax, &ebx, &ecx, &edx); cache_eax.full = eax; - } while (cache_eax.split.type != CTYPE_NULL); + } while (cache_eax.split.type != CTYPE_NULL && i != CTYPE_MAX); return i; } -- 2.7.4