From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53021) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eMPxZ-0000B2-6D for qemu-devel@nongnu.org; Tue, 05 Dec 2017 22:01:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eMPxW-0000cp-54 for qemu-devel@nongnu.org; Tue, 05 Dec 2017 22:01:21 -0500 Received: from mga05.intel.com ([192.55.52.43]:40997) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eMPxV-0000aY-SO for qemu-devel@nongnu.org; Tue, 05 Dec 2017 22:01:18 -0500 Date: Wed, 6 Dec 2017 10:44:43 +0800 From: "Liu, Yi L" Message-ID: <20171206024443.GA1164@sky-dev> References: <20171205205409.5348.53070.stgit@gimli.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171205205409.5348.53070.stgit@gimli.home> Subject: Re: [Qemu-devel] [PATCH for-2.11] vfio: Fix vfio-kvm group registration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: qemu-devel@nongnu.org, aik@ozlabs.ru, eric.auger@redhat.com On Tue, Dec 05, 2017 at 02:09:07PM -0700, Alex Williamson wrote: > Commit 8c37faa475f3 ("vfio-pci, ppc64/spapr: Reorder group-to-container > attaching") moved registration of groups with the vfio-kvm device from > vfio_get_group() to vfio_connect_container(), but it missed the case > where a group is attached to an existing container and takes an early > exit. Perhaps this is a less common case on ppc64/spapr, but on x86 > (without viommu) all groups are connected to the same container and > thus only the first group gets registered with the vfio-kvm device. > This becomes a problem if we then hot-unplug the devices associated > with that first group and we end up with KVM being misinformed about > any vfio connections that might remain. Fix by including the call to > vfio_kvm_device_add_group() in this early exit path. > > Fixes: 8c37faa475f3 ("vfio-pci, ppc64/spapr: Reorder group-to-container attaching") > Cc: qemu-stable@nongnu.org # qemu-2.10+ > Signed-off-by: Alex Williamson > --- > > This bug also existed in QEMU 2.10, but I think the fix is sufficiently > obvious (famous last words) to propose for 2.11 at this late date. If > the first group is hot unplugged then KVM may revert to code emulation > that assumes no non-coherent DMA is present on some systems. Also for > KVMGT, if the vGPU is not the first device registered, then the > notifier to enable linkages to KVM would not be called. Please review. > Thanks, Alex, for x86, I suppose it doesn't exist in the case which viommu is exposed to guest? Regards, Yi L > > hw/vfio/common.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > index 7b2924c0ef19..7007878e345e 100644 > --- a/hw/vfio/common.c > +++ b/hw/vfio/common.c > @@ -968,6 +968,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as, > if (!ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) { > group->container = container; > QLIST_INSERT_HEAD(&container->group_list, group, container_next); > + vfio_kvm_device_add_group(group); > return 0; > } > } > >