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=-1.2 required=3.0 tests=DATE_IN_PAST_03_06, DKIM_INVALID,DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,USER_AGENT_MUTT 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 5F548C32789 for ; Thu, 8 Nov 2018 12:07:41 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 A96AA2086C for ; Thu, 8 Nov 2018 12:07:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="Z0O1JeYi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A96AA2086C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42rMVL1wWDzF3HL for ; Thu, 8 Nov 2018 23:07:38 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="Z0O1JeYi"; dkim-atps=neutral Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 42rMQV45VnzF1RB for ; Thu, 8 Nov 2018 23:04:18 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="Z0O1JeYi"; dkim-atps=neutral Received: by ozlabs.org (Postfix, from userid 1007) id 42rMQT58Dwz9sBZ; Thu, 8 Nov 2018 23:04:16 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1541678657; bh=d8oHpwuvhZOLM4oHoJ46eeJ8JZhHTDitG3HrGWRnBMI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Z0O1JeYioq3l9a+ds0lPrnu6cj/3gP4KYzj9iMwXKWxVUw++XeXfG6hk6lR6Y/toG /uQznaFiJyezq0o5r55ga9FZDxX6zmI30s4MqQ93NW9KTjLL5KA8ZIwUGgJPW9W0r/ M1qOhWHVu5PkAm3gI7yaDSSMzLC4WOZDDryKH36s= Date: Thu, 8 Nov 2018 18:16:23 +1100 From: David Gibson To: Alexey Kardashevskiy Subject: Re: [PATCH kernel 2/3] vfio_pci: Allow regions to add own capabilities Message-ID: <20181108071623.GA26872@umbus.fritz.box> References: <20181015094233.1324-1-aik@ozlabs.ru> <20181015094233.1324-3-aik@ozlabs.ru> <20181108062139.GQ5575@umbus.fritz.box> <72022e34-6cf0-3946-8049-ba3d998097f3@ozlabs.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="LZvS9be/3tNcYl/X" Content-Disposition: inline In-Reply-To: <72022e34-6cf0-3946-8049-ba3d998097f3@ozlabs.ru> User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, Alistair Popple , linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, Alex Williamson , Reza Arbab Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" --LZvS9be/3tNcYl/X Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 08, 2018 at 05:48:58PM +1100, Alexey Kardashevskiy wrote: >=20 >=20 > On 08/11/2018 17:21, David Gibson wrote: > > On Mon, Oct 15, 2018 at 08:42:32PM +1100, Alexey Kardashevskiy wrote: > >> VFIO regions already support region capabilities with a limited set of > >> fields. However the subdriver might have to report to the userspace > >> additional bits. > >> > >> This adds an add_capability() hook to vfio_pci_regops. > >> > >> This is aiming Witherspoon POWER9 machines which have multiple > >> interconnected NVIDIA V100 GPUs with coherent RAM; each GPU's RAM > >> is mapped to a system bus and to each of GPU internal system bus and > >> the GPUs use this for DMA routing as DMA trafic can go via any > >> of many NVLink2 (GPU-GPU or GPU-CPU) or even stay local within a > >> GPU. > >=20 > > This description doesn't really make clear how per-region capabilities > > are relevant to these devices. >=20 >=20 > I am confused. This patch just adds a hook, and the device specifics are > explained in the next patch where they are used... Well, my point is the last paragraph of the commit message appears to be a rationale for this change in terms of what's needed for the GPU devices. But how those described properties of the GPU mean that region capabilites are useful / necessary isn't made clear. If it's not meant to be a rationale, I'm not sure what it's doing there at all. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --LZvS9be/3tNcYl/X Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlvj4sQACgkQbDjKyiDZ s5Ih1xAA0Lr5Tj0mBKT85tbpp4uub6lvh5gJy2J+/juXrz1c2DLuSgW2ZNGWqSUN CxxWHepsSITw3xfAgs7RcBgWetsF372MLQAunAYPVRW0zzXQFBfmANKVfiUCJ9zm E7KkfprxMWFU9a4LoNe0q7Nd9U4GMGTskDD3GtnQ3o3W6iGUslyHA3nWg4t0Ggvj DCpTn9cBAmNg3dZYr11TeqmPetKeTf4IPjnubAYL7gCk/cEub1vUXxz/ZDyTFgPG PnWlELGh/KoU18+q03UYJF9pf62Gv08f8PxTzlA30b+hg8JdAC0xSSl8HOnvR2mo FLakDfeblPMk6AEbonk0oE95HQfxDHY7DyWaauGDxr3IJwVv5lQ/g9/JEO4sx1Sc mUCpH5SXwOOBPplhyertdRABXcGJYt3G9TfJuMGxdD2eK6qPOSPcninQfcaEwZfF 1yGot1TxaMvft6LUuyBJhfD7zVymWyVnRSgfSxAdhHSdArQyTFGREckbczRfr82z tXKf7DL1wQmtfjbxQb2L7Ijkvp8cWqiBgaxkR7s2qO3JmFSv40S4BpDCUVOy8hKm 15AL5eqVxa0vsevow2FAeJ3XeprS7fWNpXMhC7N3Z6Ea3GuIedbXdgKGlLogBqlX 2t8Q9AoAsaoSZtCjtzEQ1XI8PCYvvXQ1mDvo2SAo59glnFSVcU8= =Uten -----END PGP SIGNATURE----- --LZvS9be/3tNcYl/X--