Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756067Ab3GWJHy (ORCPT ); Tue, 23 Jul 2013 05:07:54 -0400 Received: from mail-oa0-f50.google.com ([209.85.219.50]:35422 "EHLO mail-oa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755826Ab3GWJHu (ORCPT ); Tue, 23 Jul 2013 05:07:50 -0400 Message-ID: <51EE47DE.5020002@ozlabs.ru> Date: Tue, 23 Jul 2013 19:07:42 +1000 From: Alexey Kardashevskiy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Benjamin Herrenschmidt CC: Alex Williamson , linuxppc-dev@lists.ozlabs.org, David Gibson , Paul Mackerras , Alexander Graf , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org Subject: Re: [PATCH 03/10] vfio: add external user support References: <1373936045-22653-1-git-send-email-aik@ozlabs.ru> <1373936045-22653-4-git-send-email-aik@ozlabs.ru> <1374546224.15429.8.camel@ul30vt.home> In-Reply-To: <1374546224.15429.8.camel@ul30vt.home> Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2080 Lines: 57 On 07/23/2013 12:23 PM, Alex Williamson wrote: > On Tue, 2013-07-16 at 10:53 +1000, Alexey Kardashevskiy wrote: >> VFIO is designed to be used via ioctls on file descriptors >> returned by VFIO. >> >> However in some situations support for an external user is required. >> The first user is KVM on PPC64 (SPAPR TCE protocol) which is going to >> use the existing VFIO groups for exclusive access in real/virtual mode >> on a host to avoid passing map/unmap requests to the user space which >> would made things pretty slow. >> >> The protocol includes: >> >> 1. do normal VFIO init operation: >> - opening a new container; >> - attaching group(s) to it; >> - setting an IOMMU driver for a container. >> When IOMMU is set for a container, all groups in it are >> considered ready to use by an external user. >> >> 2. User space passes a group fd to an external user. >> The external user calls vfio_group_get_external_user() >> to verify that: >> - the group is initialized; >> - IOMMU is set for it. >> If both checks passed, vfio_group_get_external_user() >> increments the container user counter to prevent >> the VFIO group from disposal before KVM exits. >> >> 3. The external user calls vfio_external_user_iommu_id() >> to know an IOMMU ID. PPC64 KVM uses it to link logical bus >> number (LIOBN) with IOMMU ID. >> >> 4. When the external KVM finishes, it calls >> vfio_group_put_external_user() to release the VFIO group. >> This call decrements the container user counter. >> Everything gets released. >> >> The "vfio: Limit group opens" patch is also required for the consistency. >> >> Signed-off-by: Alexey Kardashevskiy > > This looks fine to me. Is the plan to add this through the ppc tree > again? Thanks, Nope, better to add this through your tree. And faster for sure :) Thanks! -- Alexey -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/