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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 C6CEDC432C0 for ; Tue, 19 Nov 2019 15:31:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B5A122304 for ; Tue, 19 Nov 2019 15:31:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728113AbfKSPbg (ORCPT ); Tue, 19 Nov 2019 10:31:36 -0500 Received: from mga14.intel.com ([192.55.52.115]:4773 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727505AbfKSPbf (ORCPT ); Tue, 19 Nov 2019 10:31:35 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Nov 2019 07:31:33 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,324,1569308400"; d="scan'208";a="209227174" Received: from sstrehla-mobl1.ger.corp.intel.com ([10.252.16.202]) by orsmga003.jf.intel.com with ESMTP; 19 Nov 2019 07:31:28 -0800 Message-ID: Subject: Re: [virtio-dev] Re: guest / host buffer sharing ... From: Liam Girdwood To: Gurchetan Singh Cc: David Stevens , Stefan Hajnoczi , Gerd Hoffmann , Keiichi Watanabe , geoff@hostfission.com, virtio-dev@lists.oasis-open.org, Alex Lau , Alexandre Courbot , qemu-devel@nongnu.org, Tomasz Figa , Hans Verkuil , Daniel Vetter , =?ISO-8859-1?Q?St=E9phane?= Marchesin , Dylan Reid , Dmitry Morozov , Pawel Osciak , Linux Media Mailing List Date: Tue, 19 Nov 2019 15:31:27 +0000 In-Reply-To: References: <20191105105456.7xbhtistnbp272lj@sirius.home.kraxel.org> <20191106084344.GB189998@stefanha-x1.localdomain> <4a5dd822e86757f004d04af62fb7dd35ba75392d.camel@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Tue, 2019-11-12 at 14:55 -0800, Gurchetan Singh wrote: > On Tue, Nov 12, 2019 at 5:56 AM Liam Girdwood > wrote: > > > > On Mon, 2019-11-11 at 16:54 -0800, Gurchetan Singh wrote: > > > On Tue, Nov 5, 2019 at 2:55 AM Gerd Hoffmann > > > wrote: > > > > Each buffer also has some properties to carry metadata, some > > > > fixed > > > > (id, size, application), but > > > > also allow free form (name = value, framebuffers would have > > > > width/height/stride/format for example). > > > > > > Sounds a lot like the recently added DMA_BUF_SET_NAME ioctls: > > > > > > https://patchwork.freedesktop.org/patch/310349/ > > > > > > For virtio-wayland + virtio-vdec, the problem is sharing -- not > > > allocation. > > > > > > > Audio also needs to share buffers with firmware running on DSPs. > > > > > As the buffer reaches a kernel boundary, it's properties devolve > > > into > > > [fd, size]. Userspace can typically handle sharing > > > metadata. The > > > issue is the guest dma-buf fd doesn't mean anything on the host. > > > > > > One scenario could be: > > > > > > 1) Guest userspace (say, gralloc) allocates using virtio- > > > gpu. When > > > allocating, we call uuidgen() and then pass that via > > > RESOURCE_CREATE > > > hypercall to the host. > > > 2) When exporting the dma-buf, we call DMA_BUF_SET_NAME (the > > > buffer > > > name will be "virtgpu-buffer-${UUID}"). > > > 3) When importing, virtio-{vdec, video} reads the dma-buf name in > > > userspace, and calls fd to handle. The name is sent to the host > > > via > > > a > > > hypercall, giving host virtio-{vdec, video} enough information to > > > identify the buffer. > > > > > > This solution is entirely userspace -- we can probably come up > > > with > > > something in kernel space [generate_random_uuid()] if need > > > be. We > > > only need two universal IDs: {device ID, buffer ID}. > > > > > > > I need something where I can take a guest buffer and then convert > > it to > > physical scatter gather page list. I can then either pass the SG > > page > > list to the DSP firmware (for DMAC IP programming) or have the host > > driver program the DMAC directly using the page list (who programs > > DMAC > > depends on DSP architecture). > > So you need the HW address space from a guest allocation? Yes. > Would your > allocation hypercalls use something like the virtio_gpu_mem_entry > (virtio_gpu.h) and the draft virtio_video_mem_entry (draft)? IIUC, this looks like generic SG buffer allocation ? > > struct { > __le64 addr; > __le32 length; > __le32 padding; > }; > > /* VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING */ > struct virtio_gpu_resource_attach_backing { > struct virtio_gpu_ctrl_hdr hdr; > __le32 resource_id; > __le32 nr_entries; > *struct struct virtio_gpu_mem_entry */ > }; > > struct virtio_video_mem_entry { > __le64 addr; > __le32 length; > __u8 padding[4]; > }; > > struct virtio_video_resource_attach_backing { > struct virtio_video_ctrl_hdr hdr; > __le32 resource_id; > __le32 nr_entries; > }; > > > > > DSP FW has no access to userspace so we would need some additional > > API > > on top of DMA_BUF_SET_NAME etc to get physical hardware pages ? > > The dma-buf api currently can share guest memory sg-lists. Ok, IIUC buffers can either be shared using the GPU proposed APIs (above) or using the dma-buf API to share via userspace ? My preference would be to use teh more direct GPU APIs sending physical page addresses from Guest to device driver. I guess this is your use case too ? Thanks Liam > > > > > Liam > > > > > > > > ----------------------------------------------------------------- > > ---- > > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > > For additional commands, e-mail: > > virtio-dev-help@lists.oasis-open.org > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org >