From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 932D47C for ; Wed, 17 Aug 2022 07:50:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=OgQrLdq5kcs/hzWnLFRYsQLf3bF4BAzScASZVzKdEss=; b=O9A1GzrnC2Jws3P2XgaDN6BtBj aaMYi9KLwTTkyZsMQjZJBpryXirCyRo/np1yqNcbd78R/eq2ws5AA9fBx+y0a/wBVOAqULQ1EItjX xnddFmcIyEwyOffdnThWr/LaMK/zld5VSiFVwKsZnc7EAI2+qYPnR5zD2g1CtAI4+ZOS69m0BfVAG d418iYhdw9dUduJnKPoKCfI8KeugvDPEN0CEEA+5CM9VGkYtD+CQiX9AfP9HgwdG4gXL2M/WlZ0gb 9smy8ah3BrobvDISkukaEuLA4mwPPe9bXSEiQNEYsPcqBoZG31Gn5pkG3qT1F87KxDRI2nUeSdhwx sYIIUFEQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1oODo5-007tsG-GR; Wed, 17 Aug 2022 07:49:41 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 2FB9798007A; Wed, 17 Aug 2022 09:49:40 +0200 (CEST) Date: Wed, 17 Aug 2022 09:49:40 +0200 From: Peter Zijlstra To: Dan Williams Cc: Davidlohr Bueso , Mark Rutland , Dave Jiang , Jonathan Cameron , linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev, bwidawsk@kernel.org, ira.weiny@intel.com, vishal.l.verma@intel.com, alison.schofield@intel.com, a.manzanares@samsung.com, linux-arch@vger.kernel.org, Arnd Bergmann , linux-arm-kernel@lists.infradead.org, bp@alien8.de, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arch/cacheflush: Introduce flush_all_caches() Message-ID: References: <4bedc81d-62fa-7091-029e-a2e56b4f8f7a@intel.com> <20220803183729.00002183@huawei.com> <9f3705e1-de21-0f3c-12af-fd011b6d613d@intel.com> <62f40fba338af_3ce6829466@dwillia2-xfh.jf.intel.com.notmuch> <20220815160706.tqd42dv24tgb7x7y@offworld> <62fbcae511ec1_dfbc129453@dwillia2-xfh.jf.intel.com.notmuch> <20220816165301.4m4w6zsse62z4hxz@offworld> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Aug 16, 2022 at 10:42:03AM -0700, Dan Williams wrote: > I also think this cache_flush_region() API wants a prominent comment > clarifying the limited applicability of this API. I.e. that it is not > for general purpose usage, not for VMs, and only for select bare metal > scenarios that instantaneously invalidate wide swaths of memory. > Otherwise, I can now see how this looks like a potentially scary > expansion of the usage of wbinvd. This; because adding a generic API like this makes it ripe for usage. And this is absolutely the very last thing we want used. 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 388F8C25B08 for ; Wed, 17 Aug 2022 07:50:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=JmeTKVMPdoMHdgkJ0WxUlNgfmriHo4vYDgB1RyRYsfk=; b=KS85Q9Wam+kXl+ Y0qpHnzCl4o/Q1t8dqa691LQsZ+22B/kdINs1BDlhbbdp9fB7MAy2Z83eny+b4xWbkPQgG/cWGrMd +z8e+fosnweEAo7tFuHp3sZJ07wnDxoGra7AQ++UQo/wSIO5C+VH26kNoeZ2jeLCoQR/kC+y+yblr 3H7eX5zNHJhrsG+/iq4GeT1MWUMEsE8xv0+5wwtV6IoN7DvzcPQ0ffPO01k+QY3KcbSiRfyTamb29 9KzL5dZ1lMAMaR46RcVxePS9u/69Bhzx34BbpvymB5eNjrtp7Q9TzaSNK8kVZvD39PDo7MtzBmiNj 3FCCs+SuXNJQ3uVRNJFw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oODoD-00Dv4O-DM; Wed, 17 Aug 2022 07:49:49 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oODoB-00Dv1o-BK for linux-arm-kernel@bombadil.infradead.org; Wed, 17 Aug 2022 07:49:47 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=OgQrLdq5kcs/hzWnLFRYsQLf3bF4BAzScASZVzKdEss=; b=O9A1GzrnC2Jws3P2XgaDN6BtBj aaMYi9KLwTTkyZsMQjZJBpryXirCyRo/np1yqNcbd78R/eq2ws5AA9fBx+y0a/wBVOAqULQ1EItjX xnddFmcIyEwyOffdnThWr/LaMK/zld5VSiFVwKsZnc7EAI2+qYPnR5zD2g1CtAI4+ZOS69m0BfVAG d418iYhdw9dUduJnKPoKCfI8KeugvDPEN0CEEA+5CM9VGkYtD+CQiX9AfP9HgwdG4gXL2M/WlZ0gb 9smy8ah3BrobvDISkukaEuLA4mwPPe9bXSEiQNEYsPcqBoZG31Gn5pkG3qT1F87KxDRI2nUeSdhwx sYIIUFEQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1oODo5-007tsG-GR; Wed, 17 Aug 2022 07:49:41 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 2FB9798007A; Wed, 17 Aug 2022 09:49:40 +0200 (CEST) Date: Wed, 17 Aug 2022 09:49:40 +0200 From: Peter Zijlstra To: Dan Williams Cc: Davidlohr Bueso , Mark Rutland , Dave Jiang , Jonathan Cameron , linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev, bwidawsk@kernel.org, ira.weiny@intel.com, vishal.l.verma@intel.com, alison.schofield@intel.com, a.manzanares@samsung.com, linux-arch@vger.kernel.org, Arnd Bergmann , linux-arm-kernel@lists.infradead.org, bp@alien8.de, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arch/cacheflush: Introduce flush_all_caches() Message-ID: References: <4bedc81d-62fa-7091-029e-a2e56b4f8f7a@intel.com> <20220803183729.00002183@huawei.com> <9f3705e1-de21-0f3c-12af-fd011b6d613d@intel.com> <62f40fba338af_3ce6829466@dwillia2-xfh.jf.intel.com.notmuch> <20220815160706.tqd42dv24tgb7x7y@offworld> <62fbcae511ec1_dfbc129453@dwillia2-xfh.jf.intel.com.notmuch> <20220816165301.4m4w6zsse62z4hxz@offworld> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Aug 16, 2022 at 10:42:03AM -0700, Dan Williams wrote: > I also think this cache_flush_region() API wants a prominent comment > clarifying the limited applicability of this API. I.e. that it is not > for general purpose usage, not for VMs, and only for select bare metal > scenarios that instantaneously invalidate wide swaths of memory. > Otherwise, I can now see how this looks like a potentially scary > expansion of the usage of wbinvd. This; because adding a generic API like this makes it ripe for usage. And this is absolutely the very last thing we want used. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel