From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60235) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhDO9-0002LB-Sl for qemu-devel@nongnu.org; Wed, 30 Sep 2015 05:09:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZhDO5-0007hO-Pb for qemu-devel@nongnu.org; Wed, 30 Sep 2015 05:09:25 -0400 References: <1443579237-9636-1-git-send-email-david@gibson.dropbear.id.au> <1443579237-9636-7-git-send-email-david@gibson.dropbear.id.au> From: Laurent Vivier Message-ID: <560BA6BD.2000409@redhat.com> Date: Wed, 30 Sep 2015 11:09:17 +0200 MIME-Version: 1.0 In-Reply-To: <1443579237-9636-7-git-send-email-david@gibson.dropbear.id.au> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCHv3 6/7] vfio: Allow hotplug of containers onto existing guest IOMMU mappings List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson , alex.williamson@redhat.com, pbonzini@redhat.com Cc: thuth@redhat.com, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, aik@ozlabs.ru, abologna@redhat.com, gwshan@linux.vnet.ibm.com, qemu-ppc@nongnu.org On 30/09/2015 04:13, David Gibson wrote: > At present the memory listener used by vfio to keep host IOMMU mappings > in sync with the guest memory image assumes that if a guest IOMMU > appears, then it has no existing mappings. > > This may not be true if a VFIO device is hotplugged onto a guest bus > which didn't previously include a VFIO device, and which has existing > guest IOMMU mappings. > > Therefore, use the memory_region_register_iommu_notifier_replay() > function in order to fix this case, replaying existing guest IOMMU > mappings, bringing the host IOMMU into sync with the guest IOMMU. > > Signed-off-by: David Gibson > --- > hw/vfio/common.c | 23 +++++++++-------------- > 1 file changed, 9 insertions(+), 14 deletions(-) > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > index f666de2..6797208 100644 > --- a/hw/vfio/common.c > +++ b/hw/vfio/common.c > @@ -312,6 +312,11 @@ out: > rcu_read_unlock(); > } > > +static hwaddr vfio_container_granularity(VFIOContainer *container) > +{ > + return (hwaddr)1 << ctz64(container->iova_pgsizes); > +} > + > static void vfio_listener_region_add(MemoryListener *listener, > MemoryRegionSection *section) > { > @@ -369,26 +374,16 @@ static void vfio_listener_region_add(MemoryListener *listener, > * would be the right place to wire that up (tell the KVM > * device emulation the VFIO iommu handles to use). > */ > - /* > - * This assumes that the guest IOMMU is empty of > - * mappings at this point. > - * > - * One way of doing this is: > - * 1. Avoid sharing IOMMUs between emulated devices or different > - * IOMMU groups. > - * 2. Implement VFIO_IOMMU_ENABLE in the host kernel to fail if > - * there are some mappings in IOMMU. > - * > - * VFIO on SPAPR does that. Other IOMMU models may do that different, > - * they must make sure there are no existing mappings or > - * loop through existing mappings to map them into VFIO. > - */ > giommu = g_malloc0(sizeof(*giommu)); > giommu->iommu = section->mr; > giommu->container = container; > giommu->n.notify = vfio_iommu_map_notify; > QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next); > + > memory_region_register_iommu_notifier(giommu->iommu, &giommu->n); > + memory_region_iommu_replay(giommu->iommu, &giommu->n, > + vfio_container_granularity(container), > + false); I'm wondering if it has any sense to provide the "is_write" information at this level of the API: I don't think we can have access to this information when we call this function (so it will be always used with false, or called twice once with false, once with true). I think it would be better to manage this internally. - > > return; > } >