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

[Eric Auger]

Hi Robin,

On 3/4/22 1:22 PM, Robin Murphy wrote:
> On 2022-03-04 10:43, Lu Baolu wrote:
>> 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()?
>
> Urgh, this is the horrible firmware-data-ordering thing again. The
> stuff I've been saying about having to rework the whole .dma_configure
> mechanism in the near future is to fix this properly.
>
> The summary is that in patch #4, calling
> iommu_device_use_default_domain() *before* {of,acpi}_dma_configure is
> currently a problem. As things stand, the IOMMU driver ignored the
> initial iommu_probe_device() call when the device was added, since at
> that point it had no fwspec yet. In this situation,
> {of,acpi}_iommu_configure() are retriggering iommu_probe_device()
> after the IOMMU driver has seen the firmware data via .of_xlate to
> learn that it it actually responsible for the given device.

thank you for providing the info. Hope this is something Lu can work around.

Thanks!

Eric
>
> Robin.
>