Re: [PATCH v4 0/8] iommu: Remove IOMMU_DEV_FEAT_SVA/_IOPF

[Zhangfei Gao]

On Thu, 13 Mar 2025 at 17:51, Zhangfei Gao <zhangfei.gao@xxxxxxxxxx> wrote:
>
> Hi, Baolu
>
> On Thu, 13 Mar 2025 at 13:19, Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote:
> >
> > The new method for driver fault reporting support relies on the domain
> > to specify a iopf_handler. The driver should detect this and setup the
> > HW when fault capable domains are attached.
> >
> > Move SMMUv3 to use this method and have VT-D validate support during
> > attach so that all three fault capable drivers have a no-op FEAT_SVA and
> > _IOPF. Then remove them.
> >
> > This was initiated by Jason. I'm following up to remove FEAT_IOPF and
> > further clean up.
> >
> > The whole series is also available at github:
> > https://github.com/LuBaolu/intel-iommu/commits/iommu_no_feat-v4
>
> I got an issue on this branch.
>
> Linux 6.14-rc4 + iommu_no_feat-v2
> drivers/pci/quirks.c
> quirk_huawei_pcie_sva will set dma-can-stall first
> arm_smmu_probe_device will check dma-can-stall and set stall_enabled
> accordingly.

This working branch arm_smmu_probe_device is called from pci_bus_add_device
So pci_fixup_device is called first

[ 1121.314405]  arm_smmu_probe_device+0x48/0x450
[ 1121.314410]  __iommu_probe_device+0xc4/0x3c8
[ 1121.314412]  iommu_probe_device+0x40/0x90
[ 1121.314414]  acpi_dma_configure_id+0xb4/0x100
[ 1121.314417]  pci_dma_configure+0xf8/0x108
[ 1121.314421]  really_probe+0x78/0x278
[ 1121.314425]  __driver_probe_device+0x80/0x140
[ 1121.314427]  driver_probe_device+0x48/0x130
[ 1121.314430]  __device_attach_driver+0xc0/0x108
[ 1121.314432]  bus_for_each_drv+0x8c/0xf8
[ 1121.314435]  __device_attach+0x104/0x1a0
[ 1121.314437]  device_attach+0x1c/0x30
[ 1121.314440]  pci_bus_add_device+0xb8/0x1f0
[ 1121.314442]  pci_iov_add_virtfn+0x2ac/0x300
[ 1121.314446]  sriov_enable+0x204/0x468
[ 1121.314447]  pci_enable_sriov+0x20/0x40


>
> This branch
> arm_smmu_probe_device happens first, when dma-can-stall = 0, so
> stall_enabled =0.
> Then drivers/pci/quirks.c: quirk_xxx happens

This not working branch: Linux 6.14-rc6 + iommu_no_feat-v4
arm_smmu_probe_device is called by pci_device_add
Then call pci_bus_add_device -> pci_fixup_device

  215.072859]  arm_smmu_probe_device+0x48/0x450
[  215.072871]  __iommu_probe_device+0xc0/0x468
[  215.072875]  iommu_probe_device+0x40/0x90
[  215.072877]  iommu_bus_notifier+0x38/0x68
[  215.072879]  notifier_call_chain+0x80/0x148
[  215.072886]  blocking_notifier_call_chain+0x50/0x80
[  215.072889]  bus_notify+0x44/0x68
[  215.072896]  device_add+0x580/0x768
[  215.072898]  pci_device_add+0x1e8/0x568
[  215.072906]  pci_iov_add_virtfn+0x198/0x300
[  215.072910]  sriov_enable+0x204/0x468
[  215.072912]  pci_enable_sriov+0x20/0x40

pci_iov_add_virtfn:
pci_device_add(virtfn, virtfn->bus);
pci_bus_add_device(virtfn); -> pci_fixup_device(pci_fixup_final, dev);



>
> Still in checking.
>
> And this branch does not need these two patches, right?
> c7b1397bef3c iommu/arm-smmu-v3: Implement arm_smmu_get_msi_mapping_domain
> 5cd34634a73e iommu/dma: Support MSIs through nested domains
>
> Thanks