On 2022/6/24 01:02, Jerry Snitselaar wrote:
Hi Baolu & Dave,
I noticed last night that on a Sapphire Rapids system if you boot without
intel_iommu=on, the idxd driver will crash during probe in iommu_sva_bind_device().
Should there be a sanity check before calling dev_iommu_ops(), or is the expectation
that the caller would verify it is safe to call? This seemed to be uncovered by
the combination of 3f6634d997db ("iommu: Use right way to retrieve iommu_ops"), and
42a1b73852c4 ("dmaengine: idxd: Separate user and kernel pasid enabling").
[ 21.423729] BUG: kernel NULL pointer dereference, address: 0000000000000038
[ 21.445108] #PF: supervisor read access in kernel mode
[ 21.450912] #PF: error_code(0x0000) - not-present page
[ 21.456706] PGD 0
[ 21.459047] Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 21.464004] CPU: 0 PID: 1420 Comm: kworker/0:3 Not tainted 5.19.0-0.rc3.27.eln120.x86_64 #1
[ 21.464011] Hardware name: Intel Corporation EAGLESTREAM/EAGLESTREAM, BIOS EGSDCRB1.SYS.0067.D12.2110190954 10/19/2021
[ 21.464015] Workqueue: events work_for_cpu_fn
[ 21.464030] RIP: 0010:iommu_sva_bind_device+0x1d/0xe0
[ 21.464046] Code: c3 cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 57 41 56 49 89 d6 41 55 41 54 55 53 48 83 ec 08 48 8b 87 d8 02 00 00 <48> 8b 40 38 48 8b 50 10 48 83 7a 70 00 48 89 14 24 0f 84 91 00 00
[ 21.464050] RSP: 0018:ff7245d9096b7db8 EFLAGS: 00010296
[ 21.464054] RAX: 0000000000000000 RBX: ff1eadeec8a51000 RCX: 0000000000000000
[ 21.464058] RDX: ff7245d9096b7e24 RSI: 0000000000000000 RDI: ff1eadeec8a510d0
[ 21.464060] RBP: ff1eadeec8a51000 R08: ffffffffb1a12300 R09: ff1eadffbfce25b4
[ 21.464062] R10: ffffffffffffffff R11: 0000000000000038 R12: ffffffffc09f8000
[ 21.464065] R13: ff1eadeec8a510d0 R14: ff7245d9096b7e24 R15: ff1eaddf54429000
[ 21.464067] FS: 0000000000000000(0000) GS:ff1eadee7f600000(0000) knlGS:0000000000000000
[ 21.464070] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 21.464072] CR2: 0000000000000038 CR3: 00000008c0e10006 CR4: 0000000000771ef0
[ 21.464074] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 21.464076] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
[ 21.464078] PKRU: 55555554
[ 21.464079] Call Trace:
[ 21.464083] <TASK>
[ 21.464092] idxd_pci_probe+0x259/0x1070 [idxd]
[ 21.464121] local_pci_probe+0x3e/0x80
[ 21.464132] work_for_cpu_fn+0x13/0x20
[ 21.464136] process_one_work+0x1c4/0x380
[ 21.464143] worker_thread+0x1ab/0x380
[ 21.464147] ? _raw_spin_lock_irqsave+0x23/0x50
[ 21.464158] ? process_one_work+0x380/0x380
[ 21.464161] kthread+0xe6/0x110
[ 21.464168] ? kthread_complete_and_exit+0x20/0x20
[ 21.464172] ret_from_fork+0x1f/0x30
I figure either there needs to be a check in iommu_sva_bind_device, or
idxd needs to check in idxd_enable_system_pasid that that
idxd->pdev->dev.iommu is not null before it tries calling iommu_sva_bind_device.
As documented around the iommu_sva_bind_device() interface:
* iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called
first, to
* initialize the required SVA features.
idxd->pdev->dev.iommu should be checked in there.
Dave, any thoughts?
Best regards,
baolu
