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device reset handling with igb_uio

dpdk-dev [email protected] 1 participant 2 messages Nov 11, 2019 – Nov 13, 2019

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https://bugs.dpdk.org/show_bug.cgi?id=361

Bug ID: 361
Summary: device reset handling with igb_uio
Product: DPDK
Version: unspecified
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: Normal
Component: ethdev
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---

Created attachment 73
--> https://bugs.dpdk.org/attachment.cgi?id=73&action=edit
msi-x vector allocation for igb_uio after device reset

Hi,

I have a question on igb_uio.

From the below function call traces, vfio-pci module frees/allocates msi-x vector table as part of
interrupt disable/enable. Where as igb-uio module, only masks/unmasks the msi-x interrupt.
Does this mean, when using igb_uio, device can't undergo reset which clears MSI-X vector table?
How to handle device reset with igb_uio?

igb-uio:
rte_intr_disable->uio_intr_disable->igbuio_pci_irqcontrol->pci_msi_mask_irq rte_intr_enable->uio_intr_enable->igbuio_pci_irqcontrol->pci_msi_unmask_irq

igbuio_pci_open->igbuio_pci_enable_interrupts->pci_alloc_irq_vectors/request_irq igbuio_pci_release->igbuio_pci_disable_interrupts->free_irq->pci_free_irq_vectors

vfio-pci:
rte_intr_disable->vfio_disable_msix->vfio_pci_ioctl->vfio_msi_disable->pci_free_irq_vectors rte_intr_enable->vfio_enable_msix->vfio_pci_ioctl->vfio_msi_enable->pci_alloc_irq_vectors/vfio_msi_set_vector_signal->request_irq

I am using the attached hack to overcome this. What is the correct way to handle this?
This is a hack as I am assigning "udev->info.irq = -1" when interrupt is disabled to prevent uio_write from exiting.

kernel/linux/igb_uio/igb_uio.c: igbuio_pci_irqcontrol

    igbuio_pci_disable_interrupts(udev);
    udev->info.irq = -1; <-- Assigning to -1 and not 0.

Basically uio_write will not call igbuio_pci_enable_interrupts to enable the interrupts back if irq is 0.

drivers/uio/uio.c: uio_write

        if (!idev->info->irq) {
                retval = -EIO;
                goto out;
        }
        if (!idev->info->irqcontrol) {
                retval = -ENOSYS;
                goto out;
        }
        retval = idev->info->irqcontrol(idev->info, irq_on);

Regards
-Santosh

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