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Herne" , Marc Hartmayer , Eric Farman Cc: Jason Gunthorpe , Cornelia Huck , kvm@vger.kernel.org, Qian Cai , Joerg Roedel , Marek Szyprowski , linux-s390 References: <0-v2-a3c5f4429e2a+55-iommu_group_lifetime_jgg@nvidia.com> <4cb6e49e-554e-57b3-e2d3-bc911d99083f@linux.ibm.com> <20220927140541.6f727b01.alex.williamson@redhat.com> Content-Language: en-US From: Christian Borntraeger In-Reply-To: <20220927140541.6f727b01.alex.williamson@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: u5RbipeS9S4CTFHZY9uC1j9AxihcJ6Tl X-Proofpoint-GUID: FS3ot2_0L3bzuNOtVe29Ry5svUf638me Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-10-04_06,2022-09-29_03,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 bulkscore=0 adultscore=0 mlxlogscore=999 spamscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1011 mlxscore=0 impostorscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2209130000 definitions=main-2210040097 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org Am 27.09.22 um 22:05 schrieb Alex Williamson: > On Mon, 26 Sep 2022 13:03:56 -0400 > Matthew Rosato wrote: > >> On 9/22/22 8:06 PM, Jason Gunthorpe wrote: >>> The iommu_group comes from the struct device that a driver has been bound >>> to and then created a struct vfio_device against. To keep the iommu layer >>> sane we want to have a simple rule that only an attached driver should be >>> using the iommu API. Particularly only an attached driver should hold >>> ownership. >>> >>> In VFIO's case since it uses the group APIs and it shares between >>> different drivers it is a bit more complicated, but the principle still >>> holds. >>> >>> Solve this by waiting for all users of the vfio_group to stop before >>> allowing vfio_unregister_group_dev() to complete. This is done with a new >>> completion to know when the users go away and an additional refcount to >>> keep track of how many device drivers are sharing the vfio group. The last >>> driver to be unregistered will clean up the group. >>> >>> This solves crashes in the S390 iommu driver that come because VFIO ends >>> up racing releasing ownership (which attaches the default iommu_domain to >>> the device) with the removal of that same device from the iommu >>> driver. This is a side case that iommu drivers should not have to cope >>> with. >>> >>> iommu driver failed to attach the default/blocking domain >>> WARNING: CPU: 0 PID: 5082 at drivers/iommu/iommu.c:1961 iommu_detach_group+0x6c/0x80 >>> Modules linked in: macvtap macvlan tap vfio_pci vfio_pci_core irqbypass vfio_virqfd kvm nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables nfnetlink mlx5_ib sunrpc ib_uverbs ism smc uvdevice ib_core s390_trng eadm_sch tape_3590 tape tape_class vfio_ccw mdev vfio_iommu_type1 vfio zcrypt_cex4 sch_fq_codel configfs ghash_s390 prng chacha_s390 libchacha aes_s390 mlx5_core des_s390 libdes sha3_512_s390 nvme sha3_256_s390 sha512_s390 sha256_s390 sha1_s390 sha_common nvme_core zfcp scsi_transport_fc pkey zcrypt rng_core autofs4 >>> CPU: 0 PID: 5082 Comm: qemu-system-s39 Tainted: G W 6.0.0-rc3 #5 >>> Hardware name: IBM 3931 A01 782 (LPAR) >>> Krnl PSW : 0704c00180000000 000000095bb10d28 (iommu_detach_group+0x70/0x80) >>> R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 >>> Krnl GPRS: 0000000000000001 0000000900000027 0000000000000039 000000095c97ffe0 >>> 00000000fffeffff 00000009fc290000 00000000af1fda50 00000000af590b58 >>> 00000000af1fdaf0 0000000135c7a320 0000000135e52258 0000000135e52200 >>> 00000000a29e8000 00000000af590b40 000000095bb10d24 0000038004b13c98 >>> Krnl Code: 000000095bb10d18: c020003d56fc larl %r2,000000095c2bbb10 >>> 000000095bb10d1e: c0e50019d901 brasl %r14,000000095be4bf20 >>> #000000095bb10d24: af000000 mc 0,0 >>> >000000095bb10d28: b904002a lgr %r2,%r10 >>> 000000095bb10d2c: ebaff0a00004 lmg %r10,%r15,160(%r15) >>> 000000095bb10d32: c0f4001aa867 brcl 15,000000095be65e00 >>> 000000095bb10d38: c004002168e0 brcl 0,000000095bf3def8 >>> 000000095bb10d3e: eb6ff0480024 stmg %r6,%r15,72(%r15) >>> Call Trace: >>> [<000000095bb10d28>] iommu_detach_group+0x70/0x80 >>> ([<000000095bb10d24>] iommu_detach_group+0x6c/0x80) >>> [<000003ff80243b0e>] vfio_iommu_type1_detach_group+0x136/0x6c8 [vfio_iommu_type1] >>> [<000003ff80137780>] __vfio_group_unset_container+0x58/0x158 [vfio] >>> [<000003ff80138a16>] vfio_group_fops_unl_ioctl+0x1b6/0x210 [vfio] >>> pci 0004:00:00.0: Removing from iommu group 4 >>> [<000000095b5b62e8>] __s390x_sys_ioctl+0xc0/0x100 >>> [<000000095be5d3b4>] __do_syscall+0x1d4/0x200 >>> [<000000095be6c072>] system_call+0x82/0xb0 >>> Last Breaking-Event-Address: >>> [<000000095be4bf80>] __warn_printk+0x60/0x68 >>> >>> It indicates that domain->ops->attach_dev() failed because the driver has >>> already passed the point of destructing the device. >>> >>> Fixes: 9ac8545199a1 ("iommu: Fix use-after-free in iommu_release_device") >>> Reported-by: Matthew Rosato >>> Tested-by: Matthew Rosato >>> Signed-off-by: Jason Gunthorpe >>> --- >>> drivers/vfio/vfio.h | 8 +++++ >>> drivers/vfio/vfio_main.c | 68 ++++++++++++++++++++++++++-------------- >>> 2 files changed, 53 insertions(+), 23 deletions(-) >>> >>> v2 >>> - Rebase on the vfio struct device series and the container.c series >>> - Drop patches 1 & 2, we need to have working error unwind, so another >>> test is not a problem >>> - Fold iommu_group_remove_device() into vfio_device_remove_group() so >>> that it forms a strict pairing with the two allocation functions. >>> - Drop the iommu patch from the series, it needs more work and discussion >>> v1 https://lore.kernel.org/r/0-v1-ef00ffecea52+2cb-iommu_group_lifetime_jgg@nvidia.com >>> >>> This could probably use another quick sanity test due to all the rebasing, >>> Alex if you are happy let's wait for Matthew. >>> >> >> I have been re-running the same series of tests on this version (on top of vfio-next) and this still resolves the reported issue. Thanks Jason! > > Thanks all. Applied to vfio next branch for v6.1. Thanks, So now I have bisected this to a regression in our KVM CI for vfio-ap. Our testcase MultipleMdevAPMatrixTestCase hangs forever. I see virtnodedevd spinning 100% and "mdevctl stop --uuid=d70d7685-a1b5-47a1-bdea-336925e0a95d" seems to wait for something: [ 186.815543] task:mdevctl state:D stack: 0 pid: 1639 ppid: 1604 flags:0x00000001 [ 186.815546] Call Trace: [ 186.815547] [<0000002baf277386>] __schedule+0x296/0x650 [ 186.815549] [<0000002baf2777a2>] schedule+0x62/0x108 [ 186.815551] [<0000002baf27db20>] schedule_timeout+0xc0/0x108 [ 186.815553] [<0000002baf278166>] __wait_for_common+0xc6/0x250 [ 186.815556] [<000003ff800c263a>] vfio_device_remove_group.isra.0+0xb2/0x118 [vfio] [ 186.815561] [<000003ff805caadc>] vfio_ap_mdev_remove+0x2c/0x198 [vfio_ap] [ 186.815565] [<0000002baef1d4de>] device_release_driver_internal+0x1c6/0x288 [ 186.815570] [<0000002baef1b27c>] bus_remove_device+0x10c/0x198 [ 186.815572] [<0000002baef14b54>] device_del+0x19c/0x3e0 [ 186.815575] [<000003ff800d9e3a>] mdev_device_remove+0xb2/0x108 [mdev] [ 186.815579] [<000003ff800da096>] remove_store+0x7e/0x90 [mdev] [ 186.815581] [<0000002baea53c30>] kernfs_fop_write_iter+0x138/0x210 [ 186.815586] [<0000002bae98e310>] vfs_write+0x1a0/0x2f0 [ 186.815588] [<0000002bae98e6d8>] ksys_write+0x70/0x100 [ 186.815590] [<0000002baf26fe2c>] __do_syscall+0x1d4/0x200 [ 186.815593] [<0000002baf27eb42>] system_call+0x82/0xb0 Any quick idea?