[libvirt] [PATCH] device-assignment: Reset device on system reset

[Chris Wright]

* Alex Williamson (alex.williamson at redhat.com) wrote:
>  static void reset_assigned_device(DeviceState *dev)
>  {
> -    PCIDevice *d = DO_UPCAST(PCIDevice, qdev, dev);
> +    PCIDevice *pci_dev = DO_UPCAST(PCIDevice, qdev, dev);
> +    AssignedDevice *adev = DO_UPCAST(AssignedDevice, dev, pci_dev);
> +    char reset_file[64];
> +    const char reset[] = "1";
> +    int fd, ret;
> +
> +    snprintf(reset_file, sizeof(reset_file),
> +             "/sys/bus/pci/devices/0000:%02x:%02x.%01x/reset",
> +             adev->host.bus, adev->host.dev, adev->host.func);

need to consider segment: %04x:..., adev->host.seg, ...

> +    /*
> +     * Issue a device reset via pci-sysfs.  Note that we use write(2) here
> +     * and ignore the return value because some kernels have a bug that
> +     * returns 0 rather than bytes written on success, sending us into an
> +     * infinite retry loop using other write mechanisms.
> +     */
> +    fd = open(reset_file, O_WRONLY);
> +    if (fd != -1) {
> +        ret = write(fd, reset, strlen(reset));
> +        close(fd);
> +    }

This will probably fail when it's managed by libvirt.  I expect it
will need some file ownership and security label mgmt added to device
assignement path I expect.