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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 5498AC433E6 for ; Mon, 1 Feb 2021 21:52:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 172F064DE3 for ; Mon, 1 Feb 2021 21:52:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229778AbhBAVwA (ORCPT ); Mon, 1 Feb 2021 16:52:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39408 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229739AbhBAVv7 (ORCPT ); Mon, 1 Feb 2021 16:51:59 -0500 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 169B5C0613D6 for ; Mon, 1 Feb 2021 13:51:19 -0800 (PST) Received: by mail-pf1-x436.google.com with SMTP id e19so12540919pfh.6 for ; Mon, 01 Feb 2021 13:51:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:in-reply-to:message-id:references :mime-version; bh=X0Q/ZUQ4hKoawWN2B+locX1+Bltm6iYAtS5TX76PGV0=; b=JcEV6HVaeDaOOL0h5jY3uy6ve5Oys0MQOJ9U4nasE04exuRtFZbJpOIHVfWoYfle1J beI2sJhpCMqlNBKLZqSCeIYmtH728isIhOBGfVtCVebDEkV58CsHbbdI/9BFXOpwyhgi sPhuhxrbexd8U7yQKn0cHEHOHWqmMJ6kjMVmVst139NVTTYL8tb2UsrBxT/gZPOJhQTR bK3XnLbP8oRFa2gAPWEvZAP1vvQ7NrTtztwvuzEw5LaDNbCmxSFGSwPCx7byOdJRUt9C YTDIaUOkG8VOT/SQRV6U7po3pLvDqhE6/hv92a8C2KiIxOr0CrEWaO67fDJMNiOEuu4f 93zg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:mime-version; bh=X0Q/ZUQ4hKoawWN2B+locX1+Bltm6iYAtS5TX76PGV0=; b=Jp5TvMBS3QWLt+0QY5oGyVD3kFVDmZsnx7y2cHXl/ab68AabcOCtrkg3ORup881frt Iv9/g62OYMxcEc5+SLqahirXQwm/YJzu6zaxvAzgQKvelH8P0euEL+WUvLps9wjj15ZF wAOs/tmbQsK++Q1CAVgJr8+58WvzZRhn23PHXO0ThWhR3Ecgx7AsVraPVC1IgADuTqWc 2IpRm1vmPEh7YZtvYyFnFp/xTc5US3yjBTKML//ZtHnwh2a9DShUqulXFtVRcHhtEwAK Lqxq+tblqOix1xo7mxj75ig9GJbxE2lu4XY5xBBaGwNGFyhLMsvmOQUXhsnIXxLZ7mTK nVkA== X-Gm-Message-State: AOAM533wrlC68mAguPObYwMQ6+UbK01dCZ7h8aa4ekEiFrhRuhbt4NaI jinjHeMfHEBj0CJL9uOHSFLAkA== X-Google-Smtp-Source: ABdhPJy0F0JZ9njhCDrVgT94zzxXJpyJDDqlsbZrnmv0MJhPc/jsWvO86HbtsOo2O3onCME70FZzTQ== X-Received: by 2002:aa7:808b:0:b029:1ce:8a32:f5e8 with SMTP id v11-20020aa7808b0000b02901ce8a32f5e8mr3097800pff.34.1612216278371; Mon, 01 Feb 2021 13:51:18 -0800 (PST) Received: from [2620:15c:17:3:4a0f:cfff:fe51:6667] ([2620:15c:17:3:4a0f:cfff:fe51:6667]) by smtp.gmail.com with ESMTPSA id a72sm20075000pfa.126.2021.02.01.13.51.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Feb 2021 13:51:17 -0800 (PST) Date: Mon, 1 Feb 2021 13:51:16 -0800 (PST) From: David Rientjes To: Ben Widawsky cc: linux-cxl@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-pci@vger.kernel.org, Bjorn Helgaas , Chris Browy , Christoph Hellwig , Dan Williams , Ira Weiny , Jon Masters , Jonathan Cameron , Rafael Wysocki , Randy Dunlap , Vishal Verma , daniel.lll@alibaba-inc.com, "John Groves (jgroves)" , "Kelley, Sean V" Subject: Re: [PATCH 03/14] cxl/mem: Find device capabilities In-Reply-To: <20210201165352.wi7tzpnd4ymxlms4@intel.com> Message-ID: <32f33dd-97a-8b1c-d488-e5198a3d7748@google.com> References: <20210130002438.1872527-1-ben.widawsky@intel.com> <20210130002438.1872527-4-ben.widawsky@intel.com> <234711bf-c03f-9aca-e0b5-ca677add3ea@google.com> <20210201165352.wi7tzpnd4ymxlms4@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Mon, 1 Feb 2021, Ben Widawsky wrote: > On 21-01-30 15:51:49, David Rientjes wrote: > > On Fri, 29 Jan 2021, Ben Widawsky wrote: > > > > > +static int cxl_mem_setup_mailbox(struct cxl_mem *cxlm) > > > +{ > > > + const int cap = cxl_read_mbox_reg32(cxlm, CXLDEV_MB_CAPS_OFFSET); > > > + > > > + cxlm->mbox.payload_size = > > > + 1 << CXL_GET_FIELD(cap, CXLDEV_MB_CAP_PAYLOAD_SIZE); > > > + > > > + /* 8.2.8.4.3 */ > > > + if (cxlm->mbox.payload_size < 256) { > > > + dev_err(&cxlm->pdev->dev, "Mailbox is too small (%zub)", > > > + cxlm->mbox.payload_size); > > > + return -ENXIO; > > > + } > > > > Any reason not to check cxlm->mbox.payload_size > (1 << 20) as well and > > return ENXIO if true? > > If some crazy vendor wanted to ship a mailbox larger than 1M, why should the > driver not allow it? > Because the spec disallows it :)