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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [BUG]Add PCIE devie to SMMUv3 fail
Hi Sisyphean, > On 12 Dec 2022, at 5:49 am, sisyphean <sisyphean@zlw.email> wrote: > > Hi, > 在 2022/12/9 17:50, Rahul Singh 写道: >> Hi Sisyphean, >> >> > On 9 Dec 2022, at 6:15 am, sisyphean <sisyphean@zlw.email> wrote: >> > >> > Hi, >> > >> > I try to run XEN on my ARM board(Sorry, for some commercial reasons, I >> > can't tell you >> > on which platform I run XEN) and add PCIE device passthrough to DomU.But >> > an error >> > occurred while adding the PCIE device to SMMUv3. >> >> PCI passthrough support is not fully upstream to Xen on ARM. We have working >> PCI passthrough branch that you can use to test it. >> >> https://gitlab.com/xen-project/fusa/xen-integration/-/commits/integration/pci-passthrough >> >> > >> > Through reading the code and tracing debugging, the error is found in the >> > function >> > arm_smmu_add_device, which will obtain and determine whether the fwspec of >> > the >> > device to be added to SMMU exists.But for the XEN of arm, the fwspec of >> > the device is >> > created and added by judging whether the iommu field exists in the device >> > node when >> > XEN parses the device tree.However, the PCIE device does not appear in the >> > device tree, >> > so there will be no fwspec for all PCIE devices. When attempting to add a >> > PCIE device to >> > SMMU, a ENODEV error will be returned. >> >> As of now Xen doesn’t support to add PCI device to IOMMU on ARM. >> > >> > In addition, the code at xen/drivers/passthrough/pci.c also verifies the >> > above view. >> > For PCIE devices, pdev is alloc in function pci_add_device by >> > alloc_pdev.However, >> > the function alloc_pdev does not create and add fwspec to the PCIE >> > device.Therefore, >> > when function pci_add_device executes to iommu_add_device,it will get the >> > error >> > return of ENODEV. >> > >> > How can I resolve the above errors? >> >> If you want to test the PCI passthrough please follow below steps. >> >> Xen setup: >> • A checkout of the “integration/pci-passthrough” branch from the >> gitlab >> https://gitlab.com/xen-project/fusa/xen-integration/-/commits/integration/pci-passthrough >> • Pass iommu=yes and pci-passthrough=on to Xen command line to enable >> PCI passthrough. >> >> Linux Kernel setup: >> >> • Some changes are required for the kernel to work with PCI passthrough. >> First are some configuration options, enable them in kernel config. >> CONFIG_XEN=y >> CONFIG_XEN_BACKEND=y >> CONFIG_XEN_PCIDEV_BACKEND=y >> • Then a patch needs to be applied for enabling the pciback driver. >> Patch is attached in this email. >> >> Using PCI passthrough: >> >> • In order to pass a device to a guest, you first need its PCI >> address(SBDF). You can either get it from a bare-metal >> Linux running on the platform or by having pciutils installed (if you >> are using a yocto-based dom0 or have apt available), which provides lspci. >> >> For example, let's pass one ethernet interface to the guest. Running >> lspci gives us this output (truncated) : >> 0000:00:00.0 Host bridge: Ampere Computing, LLC Device e100 >> 0000:00:01.0 PCI bridge: Ampere Computing, LLC Device e101 (rev 04) >> 0000:01:00.0 Ethernet controller: Intel Corporation Ethernet >> Controller X710/X557-AT 10GBASE-T (rev 01) >> [...] >> >> We will pass one of the ethernet from the PCI network card : >> 0000:01:00.0 . >> >> • Add the following line to the guest configuration file : >> pci = ['0000:01:00.0'] >> >> • Run the following command before starting the guest : >> xl pci-assignable-add 0000:01:00.0 >> • Start the guest. The network interface should appear as 00:00.0 in >> the guest and be usable. >> >> Please let me know if you need more info. >> >> >> >> Regards, >> Rahul >> > Thank you for your reply. > After setting XEN and kernel as above, I tried the following two methods to > add a PCIE device passthrough: > 1. According to your suggestion, use the command xl pci-assignable-add > 0002:21:00.0 to set in the Dom0. But in function > iommu_do_pci_domctl, after device_assigned is called, ENODEV error is > obtained. > 2. Add xen-pciback.hide=(0002:21:00.0) to dom0-bootargs in the device tree, I > encountered the same problem as before > when initializing the kernel. In function pci_add_device, PCIE devices cannot > be added to SMMUv3. It is hard to find what is happening without logs. Could you please share the Xen and Linux boot logs so that I can check what is the root cause of this issue. > The kernel version I use is 5.10. Does this have an impact? I am using the Linux version 5.15.44 but I don’t think is because of Linux. Regards, Rahul
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