From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36189) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eMUqh-0003j5-OP for qemu-devel@nongnu.org; Wed, 06 Dec 2017 03:14:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eMUqe-0004LS-J5 for qemu-devel@nongnu.org; Wed, 06 Dec 2017 03:14:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46122) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eMUqe-0004Kq-Bs for qemu-devel@nongnu.org; Wed, 06 Dec 2017 03:14:32 -0500 References: <20171205205409.5348.53070.stgit@gimli.home> From: Auger Eric Message-ID: <6844c413-0a0c-d6b9-91bd-2805299e268b@redhat.com> Date: Wed, 6 Dec 2017 09:14:25 +0100 MIME-Version: 1.0 In-Reply-To: <20171205205409.5348.53070.stgit@gimli.home> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit 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 , qemu-devel@nongnu.org Cc: aik@ozlabs.ru Hi Alex, On 05/12/17 22:09, 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 Reviewed-by: Eric Auger Tested-by: Eric Auger Tested on arm64 Gigabyte HW with hot-detach of the 2 X540T2 PFs I don't have the "2017-12-06T08:02:07.535373Z qemu-system-aarch64: Failed to remove group 24 from KVM VFIO device: No such file or directory" anymore when detaching the second PF. Thanks Eric > --- > > 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 > > 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; > } > } > >