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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 D2168C2BA12 for ; Thu, 2 Apr 2020 22:11:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A41732072E for ; Thu, 2 Apr 2020 22:11:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="f8AKwBzN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389484AbgDBWLV (ORCPT ); Thu, 2 Apr 2020 18:11:21 -0400 Received: from mail.skyhub.de ([5.9.137.197]:39474 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726963AbgDBWLV (ORCPT ); Thu, 2 Apr 2020 18:11:21 -0400 Received: from zn.tnic (p200300EC2F0A0E00AC3E2C93ADB62CA9.dip0.t-ipconnect.de [IPv6:2003:ec:2f0a:e00:ac3e:2c93:adb6:2ca9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id F0CA41EC0BF2; Fri, 3 Apr 2020 00:11:19 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1585865480; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=61DkwClXCHZinnBsHgcGNiaGAnBYPU+s2tSXg6FKgFo=; b=f8AKwBzNXodUakPNBjyiZ2GRUvx9OJmXfDgdmtC2p1hlyRsafTGyc8LScKiijzJwZduZGz OeU3XfSVP8WRLlq5XVe75cY+lnYwJx/r4+r5XS4HXI1rRr5sQjmS0bbGy1fP7U7Pmblv5l a5rKNSbcAjwKAR0Si0kXAdKMmde3nws= Date: Fri, 3 Apr 2020 00:11:09 +0200 From: Borislav Petkov To: Balbir Singh Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, tony.luck@intel.com, keescook@chromium.org, x86@kernel.org, benh@kernel.crashing.org, dave.hansen@intel.com Subject: Re: [PATCH 3/3] arch/x86: Optionally flush L1D on context switch Message-ID: <20200402221109.GJ9352@zn.tnic> References: <20200402062401.29856-1-sblbir@amazon.com> <20200402062401.29856-4-sblbir@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200402062401.29856-4-sblbir@amazon.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 02, 2020 at 05:24:01PM +1100, Balbir Singh wrote: > +int enable_l1d_flush_for_task(struct task_struct *tsk) > +{ > + struct page *page; > + int ret = 0; > + > + if (static_cpu_has(X86_FEATURE_FLUSH_L1D)) > + goto done; > + > + page = READ_ONCE(l1d_flush_pages); > + if (unlikely(!page)) { > + mutex_lock(&l1d_flush_mutex); > + if (!l1d_flush_pages) { > + l1d_flush_pages = alloc_l1d_flush_pages(); > + if (!l1d_flush_pages) > + return -ENOMEM; Do I see it correctly that you'll return here with l1d_flush_mutex still held? > + } > + mutex_unlock(&l1d_flush_mutex); > + } > + /* I don't think we need to worry about KSM */ Pls use passive voice: no "we" or "I", etc. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette