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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 44E3BC54FD0 for ; Fri, 24 Apr 2020 16:15:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EBF7820700 for ; Fri, 24 Apr 2020 16:15:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="DPuImGdy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EBF7820700 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 93F898E0006; Fri, 24 Apr 2020 12:15:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 91EAD8E0003; Fri, 24 Apr 2020 12:15:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 852E28E0006; Fri, 24 Apr 2020 12:15:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0092.hostedemail.com [216.40.44.92]) by kanga.kvack.org (Postfix) with ESMTP id 6C75C8E0003 for ; Fri, 24 Apr 2020 12:15:30 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 2E579180AD81A for ; Fri, 24 Apr 2020 16:15:30 +0000 (UTC) X-FDA: 76743248820.27.knot41_874cafbd15d1b X-HE-Tag: knot41_874cafbd15d1b X-Filterd-Recvd-Size: 6654 Received: from mail-wr1-f66.google.com (mail-wr1-f66.google.com [209.85.221.66]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Fri, 24 Apr 2020 16:15:29 +0000 (UTC) Received: by mail-wr1-f66.google.com with SMTP id s10so11584450wrr.0 for ; Fri, 24 Apr 2020 09:15:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Idx0f9VzAYOz075Su4V0hEG5kdQJUA0mndsEQAxj7CY=; b=DPuImGdyRTvhJHopunYbOa7ImxPuUzyrtULpu0sZCqLBz77We1xeyOqB55aQbJEaJJ j2xp5RKoMQX9dHxL2J15kFEgLoTrt41Hu00vDPtiv2PEnttVpk4oCuh2EVT4Ox+dOt2b iLtVlEGT/OX9d0OHbRDM+B3pE6ixNvKKwR21ZTm0CofMx+XKkCbV4TEYRkU9g88zmArp IHgnx8PCP8JrXSVoUdZ6fkdx2mIYL9hWjilwYz/CHfh3G4dhSZxCZTJJLO6CQsSLroxU K73piG72Q6p5GLs809hMyYvfo+xhYQkmWcrmF95C838KH9VbfeW67zr5bGXauTGJnLXb 6YWw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Idx0f9VzAYOz075Su4V0hEG5kdQJUA0mndsEQAxj7CY=; b=fRh5cl7n/BsK48XdtT+ZN2KpYKAcQEzFb+TOCExCsWI4TzHgwlA4QyK5kDJo6ArsC2 JQlphnk1f3zUzP+8oJKisOsWpm6UuintGlR+0iXzLk3zTxESpUDTwFSQIwGXTfcbpM1i lAK9L2EXV3HeRjqH3OJnFGhXcp1UyhD6BGpYeCLI6qUlMNmcG+qN8Gdjcv9a7TYr+zsr xG4n/qUgc0RLgaepf6ZlqYIyWNkaHoLq8kRgL0ydMMIGOUb2ztrhpnEynQbN1xOW56ir b8IorOHwsBJJVTCrL2xJHd0EOFKU1mry3AkIyD/jZi5ISp1UTJz4T2DMV+ycjBpsfigQ I3vg== X-Gm-Message-State: AGi0PuZUsaxkeqE1658xXEu0ccQcD1To0ChpmLH1R9y3cZbR0xsVA3WE PSi2ZoJfeyiKUwrxA1H8ehqMypJGnkWmOKGZiXY= X-Google-Smtp-Source: APiQypKBhUemOuLMKvtN863YBUGq3r2q3WRk+FqZM9vHrAz9gmZyYFTSqSyL5FIV559HrbHK0FA8s7lGWfh6qTfLdBQ= X-Received: by 2002:a5d:5085:: with SMTP id a5mr12789572wrt.394.1587744928469; Fri, 24 Apr 2020 09:15:28 -0700 (PDT) MIME-Version: 1.0 References: <59cda41f-170c-a1ad-a345-bc38b9ed4d73@arm.com> In-Reply-To: <59cda41f-170c-a1ad-a345-bc38b9ed4d73@arm.com> From: Shaik Ameer Basha Date: Fri, 24 Apr 2020 21:45:16 +0530 Message-ID: Subject: Re: IOVA allocation dependency between firmware buffer and remaining buffers To: Robin Murphy Cc: Ajay kumar , Linux IOMMU , linux-mm@kvack.org, Joerg Roedel , Marek Szyprowski , Rob Clark , Thierry Reding , jean-philippe@linaro.org, will@kernel.org, hch@lst.de, baolu.lu@linux.intel.com, Shaik Ameer Basha Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 24, 2020 at 8:59 PM Robin Murphy wrote: > > On 2020-04-24 4:04 pm, Ajay kumar wrote: > > Can someone check this? > > > > On Mon, Apr 20, 2020 at 9:24 PM Ajay kumar wrote: > >> > >> Hi All, > >> > >> I have an IOMMU master which has limitations as mentioned below: > >> 1) The IOMMU master internally executes a firmware, and the firmware memory > >> is allocated by the same master driver. > >> The firmware buffer address should be of the lowest range than other address > >> allocated by the device, or in other words, all the remaining buffer addresses > >> should always be in a higher range than the firmware address. > >> 2) None of the buffer addresses should go beyond 0xC000_0000 > > That particular constraint could (and perhaps should) be expressed as a > DMA mask/limit for the device, but if you have specific requirements to Yes Robin. We do use 0xC000_0000 address to set the DMA mask in our driver. > place buffers at particular addresses then you might be better off > managing your own IOMMU domain like some other (mostly DRM) drivers do. If you remember any of such drivers can you please point the driver path ? > The DMA APIs don't offer any guarantees about what addresses you'll get > other than that they won't exceed the appropriate mask. True, we have gone through most of the APIs and didn't find any way to match our requirements with the existing DMA APIs > > >> example: > >> If firmware buffer address is buf_fw = 0x8000_5000; > >> All other addresses given to the device should be greater than > >> (0x8000_5000 + firmware size) and less than 0xC000_0000 > > Out of curiosity, how do you control that in the no-IOMMU or IOMMU > passthrough cases? We manage the no-IOMMU or pass through cases using the reserved-memory. > > Robin. > > >> Currently, this is being handled with one of the below hacks: > >> 1) By keeping dma_mask in lower range while allocating firmware buffer, > >> and then increasing the dma_mask to higher range for other buffers. > >> 2) By reserving IOVA for firmware at the lowest range and creating direct mappings for the same. > >> > >> I want to know if there is a better way this can be handled with current framework, > >> or if anybody is facing similar problems with their devices, > >> please share how it is taken care. > >> > >> I also think there should be some way the masters can specify the IOVA > >> range they want to limit to for current allocation. > >> Something like a new iommu_ops callback like below: > >> limit_iova_alloc_range(dev, iova_start, iova_end) > >> > >> And, in my driver, the sequence will be: > >> limit_iova_alloc_range(dev, 0x0000_0000, 0x1000_0000); /* via helpers */ > >> alloc( ) firmware buffer using DMA API > >> limit_iova_alloc_range(dev, 0x1000_0000, 0xC000_0000); /* via helpers */ > >> alloc( ) other buffers using DMA API > >> Just want to understand more from you, on the new iommu_ops we suggested. Shouldn't device have that flexibility to allocate IOVA as per it's requirement? If you see our device as example, we need to have control on the allocated IOVA region based on where device is using this buffer. If we have these callbacks in place, then the low level IOMMU driver can implement and manage such requests when needed. If this can't be taken forward for some right reasons, then we will definitely try to understand on how to manage the IOMMU domain from our driver as per your suggestion - Shaik. > >> Thanks, > >> Ajay Kumar