linux-kernel - Re: [PATCH v2 00/17] Add Nested Translation Support for SMMUv3

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Message-ID: <7650f32d-6d4d-012e-b14b-538529de0577@linaro.org>
Date:   Fri, 26 May 2023 09:58:52 +0800
From:   zhangfei gao <zhangfei.gao@...aro.org>
To:     Nicolin Chen <nicolinc@...dia.com>
Cc:     jgg@...dia.com, robin.murphy@....com, will@...nel.org,
        eric.auger@...hat.com, kevin.tian@...el.com,
        baolu.lu@...ux.intel.com, joro@...tes.org,
        shameerali.kolothum.thodi@...wei.com, jean-philippe@...aro.org,
        linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        alex.williamson@...hat.com, yi.l.liu@...el.com
Subject: Re: [PATCH v2 00/17] Add Nested Translation Support for SMMUv3


在 2023/5/26 07:42, Nicolin Chen 写道:
> On Tue, May 16, 2023 at 11:12:44AM +0800, Zhangfei Gao wrote:
>
>>>> However when debugging hotplug PCI device, it still does not work,
>>>> Segmentation fault same as 6.2.
>>>>
>>>> guest kernel
>>>> CONFIG_HOTPLUG_PCI_PCIE=y
>>>>
>>>> boot guest (this info does not appear in 6.2)
>>>> qemu-system-aarch64: -device
>>>> vfio-pci,host=0000:76:00.1,bus=pci.1,addr=0x0,id=acc1,iommufd=iommufd0:
>>>> Failed to set data -1
>>>> qemu-system-aarch64: -device
>>>> vfio-pci,host=0000:76:00.1,bus=pci.1,addr=0x0,id=acc1,iommufd=iommufd0:
>>>> failed to set device data
>>> Hmm.. I wonder what fails the set_dev_data ioctl...
>> Simply debug, it is because dev_data.sid=0, causing
>> arm_smmu_set_dev_user_data fail
> I found that too. The input pci bus number is 1, yet the in
> the context of set_dev_data, the pci bus number is 0, which
> resulted in a 0-valued sid. I will take another look to get
> why.
>
>>>> $ sudo nc -U /tmp/qmpm_1.socket
>>>> (qemu) info pci
>>>> (qemu) device_del acc1
>>>>
>>>> guest:
>>>> qemu-system-aarch64: IOMMU_IOAS_UNMAP failed: No such file or directory
>>>> qemu-system-aarch64: vfio_container_dma_unmap(0xaaaae1fc0380,
>>>> 0x8000000000, 0x10000) = -2 (No such file or directory)
>>  From ex-email reply
>> (Eric) In qemu arm virt machine 0x8000000000 matches the PCI MMIO region.
>> (Yi) Currently, iommufd kernel part doesn't support mapping device BAR MMIO.
>> This is a known gap.
> OK.
>
>>>> qemu-system-aarch64: Failed to unset data -1
>>>> Segmentation fault (core dumped).  // also happened in 6.2
>>> Hmm, would it be possible for you to run the test again by
>>> adding the following tracers to your QEMU command?
>>>      --trace "iommufd*" \
>>>      --trace "smmu*" \
>>>      --trace "vfio_*" \
>>>      --trace "pci_*"
>>>
>> Have sent you the log directly, since it is too big.
> I have found two missing pieces in the device detach routine.
> Applying the following should fix the crash at hotplug path.
>
> ----------------------------------------------------------------------------
> diff --git a/hw/vfio/container-base.c b/hw/vfio/container-base.c
> index 89a256efa999..2344307523cb 100644
> --- a/hw/vfio/container-base.c
> +++ b/hw/vfio/container-base.c
> @@ -151,8 +151,10 @@ void vfio_container_destroy(VFIOContainer *container)
>       }
>
>       QLIST_FOREACH_SAFE(giommu, &container->giommu_list, giommu_next, tmp) {
> -        memory_region_unregister_iommu_notifier(
> -                MEMORY_REGION(giommu->iommu_mr), &giommu->n);
> +        if (giommu->n.notifier_flags) {
> +            memory_region_unregister_iommu_notifier(
> +                    MEMORY_REGION(giommu->iommu_mr), &giommu->n);
> +        }
>           QLIST_REMOVE(giommu, giommu_next);
>           g_free(giommu);
>       }
> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
> index 844c60892db2..35d31480390d 100644
> --- a/hw/vfio/iommufd.c
> +++ b/hw/vfio/iommufd.c
> @@ -652,6 +652,9 @@ found:
>        */
>       if (QLIST_EMPTY(&container->hwpt_list)) {
>           vfio_as_del_container(space, bcontainer);
> +        if (bcontainer->nested) {
> +            memory_listener_unregister(& bcontainer->prereg_listener);
> +        }
>       }
>       __vfio_device_detach_container(vbasedev, container, &err);
>       if (err) {
> ----------------------------------------------------------------------------
>
> Would you please try your case with it?


Yes, this solve the hotplug segmentation fault

Still report

qemu-system-aarch64: IOMMU_IOAS_UNMAP failed: No such file or directory
qemu-system-aarch64: vfio_container_dma_unmap(0xaaaae622e300, 
0x8000000000, 0x10000) = -2 (No such file or directory)
qemu-system-aarch64: Failed to unset data -1 (only the first time of 
device_del)

Test with device_del and device_add

Thanks.