Re: [PATCH v7 01/11] iommu: Add DMA ownership management interfaces

[Lu Baolu]

Hi Eric,

On 2022/3/4 18:34, Eric Auger wrote:
> I hit a WARN_ON() when unbinding an e1000e driver just after boot:
>
> sudo modprobe -v vfio-pci
> echo vfio-pci | sudo tee -a
> /sys/bus/pci/devices/0004:01:00.0/driver_override
> vfio-pci
> echo 0004:01:00.0 | sudo tee -a  /sys/bus/pci/drivers/e1000e/unbind
>
>
> [  390.042811] ------------[ cut here ]------------
> [  390.046468] WARNING: CPU: 42 PID: 5589 at drivers/iommu/iommu.c:3123
> iommu_device_unuse_default_domain+0x68/0x100
> [  390.056710] Modules linked in: vfio_pci vfio_pci_core vfio_virqfd
> vfio_iommu_type1 vfio xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT
> nf_reject_ipv4 nft_compat nft_chain_nat nf_nat nf_conntrack
> nf_defrag_ipv6 nf_defrag_ipv4 nf_tables nfnetlink bridge stp llc rfkill
> sunrpc vfat fat mlx5_ib ib_uverbs ib_core acpi_ipmi ipmi_ssif
> ipmi_devintf ipmi_msghandler cppc_cpufreq drm xfs libcrc32c mlx5_core sg
> mlxfw crct10dif_ce tls ghash_ce sha2_ce sha256_arm64 sha1_ce sbsa_gwdt
> e1000e psample sdhci_acpi ahci_platform sdhci libahci_platform qcom_emac
> mmc_core hdma hdma_mgmt dm_mirror dm_region_hash dm_log dm_mod fuse
> [  390.110618] CPU: 42 PID: 5589 Comm: tee Kdump: loaded Not tainted
> 5.17.0-rc4-lu-v7-official+ #24
> [  390.119384] Hardware name: WIWYNN QDF2400 Reference Evaluation
> Platform CV90-LA115-P120/QDF2400 Customer Reference Board, BIOS 0ACJA570
> 11/05/2018
> [  390.132492] pstate: a0400005 (NzCv daif +PAN -UAO -TCO -DIT -SSBS
> BTYPE=--)
> [  390.139436] pc : iommu_device_unuse_default_domain+0x68/0x100
> [  390.145165] lr : iommu_device_unuse_default_domain+0x38/0x100
> [  390.150894] sp : ffff80000fbb3bc0
> [  390.154193] x29: ffff80000fbb3bc0 x28: ffff03c0cf6b2400 x27:
> 0000000000000000
> [  390.161311] x26: 0000000000000000 x25: 0000000000000000 x24:
> ffff03c0c7cc5720
> [  390.168429] x23: ffff03c0c2b9d150 x22: ffffb4e61df223f8 x21:
> ffffb4e61df223f8
> [  390.175547] x20: ffff03c7c03c3758 x19: ffff03c7c03c3700 x18:
> 0000000000000000
> [  390.182665] x17: 0000000000000000 x16: 0000000000000000 x15:
> 0000000000000000
> [  390.189783] x14: 0000000000000000 x13: 0000000000000030 x12:
> ffff03c0d519cd80
> [  390.196901] x11: 7f7f7f7f7f7f7f7f x10: 0000000000000dc0 x9 :
> ffffb4e620b54f8c
> [  390.204019] x8 : ffff03c0cf6b3220 x7 : ffff4ef132bba000 x6 :
> 00000000000000ff
> [  390.211137] x5 : ffff03c0c2b9f108 x4 : ffff03c0d51f6438 x3 :
> 0000000000000000
> [  390.218255] x2 : ffff03c0cf6b2400 x1 : 0000000000000000 x0 :
> 0000000000000000
> [  390.225374] Call trace:
> [  390.227804]  iommu_device_unuse_default_domain+0x68/0x100
> [  390.233187]  pci_dma_cleanup+0x38/0x44
> [  390.236919]  __device_release_driver+0x1a8/0x260
> [  390.241519]  device_driver_detach+0x50/0xd0
> [  390.245686]  unbind_store+0xf8/0x120
> [  390.249245]  drv_attr_store+0x30/0x44
> [  390.252891]  sysfs_kf_write+0x50/0x60
> [  390.256537]  kernfs_fop_write_iter+0x134/0x1cc
> [  390.260964]  new_sync_write+0xf0/0x18c
> [  390.264696]  vfs_write+0x230/0x2d0
> [  390.268082]  ksys_write+0x74/0x100
> [  390.271467]  __arm64_sys_write+0x28/0x3c
> [  390.275373]  invoke_syscall.constprop.0+0x58/0xf0
> [  390.280061]  el0_svc_common.constprop.0+0x160/0x164
> [  390.284922]  do_el0_svc+0x34/0xcc
> [  390.288221]  el0_svc+0x30/0x140
> [  390.291346]  el0t_64_sync_handler+0xa4/0x130
> [  390.295599]  el0t_64_sync+0x1a0/0x1a4
> [  390.299245] ---[ end trace 0000000000000000 ]---
>
>
> I put some traces in the code and I can see that iommu_device_use_default_domain() effectively is called on 0004:01:00.0 e1000e device on pci_dma_configure() but at that time the iommu group is NULL:
> [   10.569427] e1000e 0004:01:00.0: ------ ENTRY pci_dma_configure driver_managed_area=0
> [   10.569431] e1000e 0004:01:00.0: **** iommu_device_use_default_domain ENTRY
> [   10.569433] e1000e 0004:01:00.0: **** iommu_device_use_default_domain no group
> [   10.569435] e1000e 0004:01:00.0: pci_dma_configure iommu_device_use_default_domain returned 0
> [   10.569492] e1000e 0004:01:00.0: Adding to iommu group 3
>
> ^^^the group is added after the
> iommu_device_use_default_domain() call
> So the group->owner_cnt is not incremented as expected.

Thank you for reporting this. Do you have any idea why the driver is
loaded before iommu_probe_device()?

Best regards,
baolu