From patchwork Wed Apr 17 21:33:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fenghua Yu X-Patchwork-Id: 10906297 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5925F1390 for ; Wed, 17 Apr 2019 21:46:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 493B928A96 for ; Wed, 17 Apr 2019 21:46:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3C73E28BAC; Wed, 17 Apr 2019 21:46:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E4E8B28A96 for ; Wed, 17 Apr 2019 21:46:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387971AbfDQVq3 (ORCPT ); Wed, 17 Apr 2019 17:46:29 -0400 Received: from mga12.intel.com ([192.55.52.136]:20157 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387483AbfDQVmS (ORCPT ); Wed, 17 Apr 2019 17:42:18 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Apr 2019 14:42:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,363,1549958400"; d="scan'208";a="224441141" Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by orsmga001.jf.intel.com with ESMTP; 17 Apr 2019 14:42:16 -0700 From: Fenghua Yu To: "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "H Peter Anvin" , "Paolo Bonzini" , "Dave Hansen" , "Ashok Raj" , "Peter Zijlstra" , "Ravi V Shankar" , "Xiaoyao Li " , "Christopherson Sean J" , "Kalle Valo" , "Michael Chan" Cc: "linux-kernel" , "x86" , kvm@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, Fenghua Yu Subject: [PATCH v7 04/21] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access Date: Wed, 17 Apr 2019 14:33:54 -0700 Message-Id: <1555536851-17462-5-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1555536851-17462-1-git-send-email-fenghua.yu@intel.com> References: <1555536851-17462-1-git-send-email-fenghua.yu@intel.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP set_cpu_cap() calls locked BTS and clear_cpu_cap() calls locked BTR to operate on bitmap defined in x86_capability. Locked BTS/BTR accesses a single unsigned long location. In 64-bit mode, the location is at: base address of x86_capability + (bit offset in x86_capability / 64) * 8 Since base address of x86_capability may not be aligned to unsigned long, the single unsigned long location may cross two cache lines and accessing the location by locked BTS/BTR introductions will cause split lock. To fix the split lock issue, align x86_capability to size of unsigned long so that the location will be always within one cache line. Changing x86_capability's type to unsigned long may also fix the issue because x86_capability will be naturally aligned to size of unsigned long. But this needs additional code changes. So choose the simpler solution by setting the array's alignment to size of unsigned long. Signed-off-by: Fenghua Yu --- arch/x86/include/asm/processor.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 2bb3a648fc12..7c62b9ad6e5a 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -93,7 +93,9 @@ struct cpuinfo_x86 { __u32 extended_cpuid_level; /* Maximum supported CPUID level, -1=no CPUID: */ int cpuid_level; - __u32 x86_capability[NCAPINTS + NBUGINTS]; + /* Aligned to size of unsigned long to avoid split lock in atomic ops */ + __u32 x86_capability[NCAPINTS + NBUGINTS] + __aligned(sizeof(unsigned long)); char x86_vendor_id[16]; char x86_model_id[64]; /* in KB - valid for CPUS which support this call: */