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=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 43471C2BB85 for ; Thu, 16 Apr 2020 10:25:14 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 146AC21D82 for ; Thu, 16 Apr 2020 10:25:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="W2uMPyIU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 146AC21D82 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 481ED6EB36; Thu, 16 Apr 2020 10:25:13 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by gabe.freedesktop.org (Postfix) with ESMTPS id 31FEF6EB36 for ; Thu, 16 Apr 2020 10:25:12 +0000 (UTC) Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 457552192A; Thu, 16 Apr 2020 10:25:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587032711; bh=lKwbnEdUTTba3AJVKzmuvKJ2X9FO6D210s3WkJT/zZQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=W2uMPyIU+mZIh4oNdYX1OAnVqWzjphWKBN2GBWPvfUx+i38L7tiemQkppi+gxHlZW JlF2YNYah1X+HwUMB3yZOQ35X0ro+n9Y78fNlVj/EfyxfoZZsOyB5MYhQSYl8R4ERW H/AbdIG7irc1sh8ffKpw66MvAQ+0sft+pvgi+fyg= Date: Thu, 16 Apr 2020 12:25:08 +0200 From: Greg Kroah-Hartman To: John Stultz Subject: Re: [PATCH] staging: android: ion: Skip sync if not mapped Message-ID: <20200416102508.GA820251@kroah.com> References: <20200414134629.54567-1-orjan.eide@arm.com> <20200414141849.55654-1-orjan.eide@arm.com> <20200414142810.GA958163@kroah.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: driverdevel , Laura Abbott , Todd Kjos , Lecopzer Chen , Arnd Bergmann , Daniel Vetter , lkml , dri-devel , "moderated list:DMA BUFFER SHARING FRAMEWORK" , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Anders Pedersen , Joel Fernandes , "Darren Hart \(VMware\)" , =?iso-8859-1?Q?=D8rjan?= Eide , nd , Martijn Coenen , Christian Brauner , linux-media@vger.kernel.org Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, Apr 14, 2020 at 09:41:31PM -0700, John Stultz wrote: > On Tue, Apr 14, 2020 at 7:28 AM Greg Kroah-Hartman > wrote: > > > > On Tue, Apr 14, 2020 at 04:18:47PM +0200, =D8rjan Eide wrote: > > > Only sync the sg-list of an Ion dma-buf attachment when the attachment > > > is actually mapped on the device. > > > > > > dma-bufs may be synced at any time. It can be reached from user space > > > via DMA_BUF_IOCTL_SYNC, so there are no guarantees from callers on wh= en > > > syncs may be attempted, and dma_buf_end_cpu_access() and > > > dma_buf_begin_cpu_access() may not be paired. > > > > > > Since the sg_list's dma_address isn't set up until the buffer is used > > > on the device, and dma_map_sg() is called on it, the dma_address will= be > > > NULL if sync is attempted on the dma-buf before it's mapped on a devi= ce. > > > > > > Before v5.0 (commit 55897af63091 ("dma-direct: merge swiotlb_dma_ops > > > into the dma_direct code")) this was a problem as the dma-api (at lea= st > > > the swiotlb_dma_ops on arm64) would use the potentially invalid > > > dma_address. How that failed depended on how the device handled physi= cal > > > address 0. If 0 was a valid address to physical ram, that page would = get > > > flushed a lot, while the actual pages in the buffer would not get syn= ced > > > correctly. While if 0 is an invalid physical address it may cause a > > > fault and trigger a crash. > > > > > > In v5.0 this was incidentally fixed by commit 55897af63091 ("dma-dire= ct: > > > merge swiotlb_dma_ops into the dma_direct code"), as this moved the > > > dma-api to use the page pointer in the sg_list, and (for Ion buffers = at > > > least) this will always be valid if the sg_list exists at all. > > > > > > But, this issue is re-introduced in v5.3 with > > > commit 449fa54d6815 ("dma-direct: correct the physical addr in > > > dma_direct_sync_sg_for_cpu/device") moves the dma-api back to the old > > > behaviour and picks the dma_address that may be invalid. > > > > > > dma-buf core doesn't ensure that the buffer is mapped on the device, = and > > > thus have a valid sg_list, before calling the exporter's > > > begin_cpu_access. > > > > > > Signed-off-by: =D8rjan Eide > > > --- > > > drivers/staging/android/ion/ion.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > Resubmit without disclaimer, sorry about that. > > > > > > This seems to be part of a bigger issue where dma-buf exporters assume > > > that their dma-buf begin_cpu_access and end_cpu_access callbacks have= a > > > certain guaranteed behavior, which isn't ensured by dma-buf core. > > > > > > This patch fixes this in ion only, but it also needs to be fixed for > > > other exporters, either handled like this in each exporter, or in > > > dma-buf core before calling into the exporters. > > > > > > diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/andr= oid/ion/ion.c > > > index 38b51eace4f9..7b752ba0cb6d 100644 > > > --- a/drivers/staging/android/ion/ion.c > > > +++ b/drivers/staging/android/ion/ion.c > > > > Now that we have the dma-buff stuff in the tree, do we even need the > > ion code in the kernel anymore? Can't we delete it now? > > > = > I agree that we shouldn't be taking further (non-security/cleanup) > patches to the ION code. > = > I'd like to give developers a little bit of a transition period (I was > thinking a year, but really just one LTS release that has both would > do) where they can move their ION heaps over to dmabuf heaps and test > both against the same tree. > = > But I do think we can mark it as deprecated and let folks know that > around the end of the year it will be deleted. No one ever notices "depreciated" things, they only notice if the code is no longer there :) So I'm all for just deleting it and seeing who even notices... thanks, greg k-h _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 44D12C2BB55 for ; Thu, 16 Apr 2020 11:47:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D61621D95 for ; Thu, 16 Apr 2020 11:47:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587037647; bh=lKwbnEdUTTba3AJVKzmuvKJ2X9FO6D210s3WkJT/zZQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=MmF7hEpII7jhJm03HkqYmEqrWog2Dp3iSk3j7srLiV36iPQ8h2cF0Vi/N5owrIeMe x0BuLyJsZtLJXUYjBRe1Gs5ypmAweSoBV6Ow1tcb6fwtIl1YN/uMQzYzM/OvxiJTfm nr3SxHUDPID8cdqAPFit+CqMYq2oNkVvciFWw7Sk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2506636AbgDPLrX (ORCPT ); Thu, 16 Apr 2020 07:47:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:55366 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2504827AbgDPKZO (ORCPT ); Thu, 16 Apr 2020 06:25:14 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 457552192A; Thu, 16 Apr 2020 10:25:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587032711; bh=lKwbnEdUTTba3AJVKzmuvKJ2X9FO6D210s3WkJT/zZQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=W2uMPyIU+mZIh4oNdYX1OAnVqWzjphWKBN2GBWPvfUx+i38L7tiemQkppi+gxHlZW JlF2YNYah1X+HwUMB3yZOQ35X0ro+n9Y78fNlVj/EfyxfoZZsOyB5MYhQSYl8R4ERW H/AbdIG7irc1sh8ffKpw66MvAQ+0sft+pvgi+fyg= Date: Thu, 16 Apr 2020 12:25:08 +0200 From: Greg Kroah-Hartman To: John Stultz Cc: driverdevel , nd , Todd Kjos , Lecopzer Chen , Arnd Bergmann , Daniel Vetter , lkml , dri-devel , "moderated list:DMA BUFFER SHARING FRAMEWORK" , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Anders Pedersen , Joel Fernandes , "Darren Hart (VMware)" , =?iso-8859-1?Q?=D8rjan?= Eide , Laura Abbott , Martijn Coenen , Sumit Semwal , Christian Brauner , linux-media@vger.kernel.org Subject: Re: [PATCH] staging: android: ion: Skip sync if not mapped Message-ID: <20200416102508.GA820251@kroah.com> References: <20200414134629.54567-1-orjan.eide@arm.com> <20200414141849.55654-1-orjan.eide@arm.com> <20200414142810.GA958163@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Tue, Apr 14, 2020 at 09:41:31PM -0700, John Stultz wrote: > On Tue, Apr 14, 2020 at 7:28 AM Greg Kroah-Hartman > wrote: > > > > On Tue, Apr 14, 2020 at 04:18:47PM +0200, Ørjan Eide wrote: > > > Only sync the sg-list of an Ion dma-buf attachment when the attachment > > > is actually mapped on the device. > > > > > > dma-bufs may be synced at any time. It can be reached from user space > > > via DMA_BUF_IOCTL_SYNC, so there are no guarantees from callers on when > > > syncs may be attempted, and dma_buf_end_cpu_access() and > > > dma_buf_begin_cpu_access() may not be paired. > > > > > > Since the sg_list's dma_address isn't set up until the buffer is used > > > on the device, and dma_map_sg() is called on it, the dma_address will be > > > NULL if sync is attempted on the dma-buf before it's mapped on a device. > > > > > > Before v5.0 (commit 55897af63091 ("dma-direct: merge swiotlb_dma_ops > > > into the dma_direct code")) this was a problem as the dma-api (at least > > > the swiotlb_dma_ops on arm64) would use the potentially invalid > > > dma_address. How that failed depended on how the device handled physical > > > address 0. If 0 was a valid address to physical ram, that page would get > > > flushed a lot, while the actual pages in the buffer would not get synced > > > correctly. While if 0 is an invalid physical address it may cause a > > > fault and trigger a crash. > > > > > > In v5.0 this was incidentally fixed by commit 55897af63091 ("dma-direct: > > > merge swiotlb_dma_ops into the dma_direct code"), as this moved the > > > dma-api to use the page pointer in the sg_list, and (for Ion buffers at > > > least) this will always be valid if the sg_list exists at all. > > > > > > But, this issue is re-introduced in v5.3 with > > > commit 449fa54d6815 ("dma-direct: correct the physical addr in > > > dma_direct_sync_sg_for_cpu/device") moves the dma-api back to the old > > > behaviour and picks the dma_address that may be invalid. > > > > > > dma-buf core doesn't ensure that the buffer is mapped on the device, and > > > thus have a valid sg_list, before calling the exporter's > > > begin_cpu_access. > > > > > > Signed-off-by: Ørjan Eide > > > --- > > > drivers/staging/android/ion/ion.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > Resubmit without disclaimer, sorry about that. > > > > > > This seems to be part of a bigger issue where dma-buf exporters assume > > > that their dma-buf begin_cpu_access and end_cpu_access callbacks have a > > > certain guaranteed behavior, which isn't ensured by dma-buf core. > > > > > > This patch fixes this in ion only, but it also needs to be fixed for > > > other exporters, either handled like this in each exporter, or in > > > dma-buf core before calling into the exporters. > > > > > > diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c > > > index 38b51eace4f9..7b752ba0cb6d 100644 > > > --- a/drivers/staging/android/ion/ion.c > > > +++ b/drivers/staging/android/ion/ion.c > > > > Now that we have the dma-buff stuff in the tree, do we even need the > > ion code in the kernel anymore? Can't we delete it now? > > > > I agree that we shouldn't be taking further (non-security/cleanup) > patches to the ION code. > > I'd like to give developers a little bit of a transition period (I was > thinking a year, but really just one LTS release that has both would > do) where they can move their ION heaps over to dmabuf heaps and test > both against the same tree. > > But I do think we can mark it as deprecated and let folks know that > around the end of the year it will be deleted. No one ever notices "depreciated" things, they only notice if the code is no longer there :) So I'm all for just deleting it and seeing who even notices... thanks, greg k-h