Message-ID: <b1a5db0a-0373-5ca0-6256-85a96d029ec9@linux.intel.com>
Date:   Mon, 7 Mar 2022 11:27:35 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Robin Murphy <robin.murphy@....com>, eric.auger@...hat.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>
Cc:     baolu.lu@...ux.intel.com, Chaitanya Kulkarni <kch@...dia.com>,
        kvm@...r.kernel.org, Stuart Yoder <stuyoder@...il.com>,
        rafael@...nel.org, David Airlie <airlied@...ux.ie>,
        linux-pci@...r.kernel.org, Cornelia Huck <cohuck@...hat.com>,
        linux-kernel@...r.kernel.org,
        Jonathan Hunter <jonathanh@...dia.com>,
        iommu@...ts.linux-foundation.org,
        Thierry Reding <thierry.reding@...il.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Diana Craciun <diana.craciun@....nxp.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Li Yang <leoyang.li@....com>, Will Deacon <will@...nel.org>,
        Dmitry Osipenko <digetx@...il.com>
Subject: Re: [PATCH v7 01/11] iommu: Add DMA ownership management interfaces

Hi Robin,

On 3/4/22 10:10 PM, Robin Murphy wrote:
> On 2022-03-04 13:55, Eric Auger wrote:
>> 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.
> 
> Hopefully it's just a case of flipping the calls around, so that 
> iommu_use_default_domain() goes at the end, and calls 
> arch_teardown_dma_ops() if it fails. From a quick skim I *think* that 
> should still work out to the desired behaviour (or at least close enough 
> that we can move forward without a circular dependency between fixes...)

This is a reasonable solution to me. Thank you for the information and
suggestion.

Eric, I have updated the patch #4 and uploaded a new version here:

https://github.com/LuBaolu/intel-iommu/commits/iommu-dma-ownership-v8

Can you please give it a try?

Best regards,
baolu

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