Re: [PATCH 3/3] Inform users about busy device assignment attempt

Michael S. Tsirkin
2009-12-15T18:44:36Z

On Tue, Dec 15, 2009 at 07:30:28PM +0100, Alexander Graf wrote:
> When using -pcidevice on a device that is already in use by a kernel driver
> all the user gets is the following (very useful) information:
>
> Failed to assign device "04:00.0" : Device or resource busy
> Failed to deassign device "04:00.0" : Invalid argument
> Error initializing device pci-assign
>
> Since I usually prefer to have my computer do the thinking for me, I figured
> it might be a good idea to check and see if a device is actually used by a
> driver. If so, tell the user.
>
> So with this patch applied you get the following output:
>
> Failed to assign device "04:00.0" : Device or resource busy
> *** The driver 'igb' is occupying your device 04:00.0.
> ***
> *** You can try the following commands to free it:
> ***
> *** $ echo "8086 150a" > /sys/bus/pci/drivers/pci-stub/new_id
> *** $ echo "0000:04:00.0" > /sys/bus/pci/drivers/igb/unbind
> *** $ echo "0000:04:00.0" > /sys/bus/pci/drivers/pci-stub/bind
> *** $ echo "8086 150a" > /sys/bus/pci/drivers/pci-stub/remove_id
> ***
> Failed to deassign device "04:00.0" : Invalid argument
> Error initializing device pci-assign
>
> That should keep people like me from doing the most obvious misuses :-).
>
> CC: Daniel P. Berrange <berrange@redhat.com>
> Signed-off-by: Alexander Graf <agraf@suse.de>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>
> v1 -> v2:
>
> - add more helpful guidance thanks to Daniel Berrange
>
> v2 -> v3:
>
> - clear name variable before using it, thus 0-terminating the string
> - fix region numbers
> - use correct unbind/bind names
>
> v3 -> v4:
>
> - split id retrieval part
> - mst comments
> ---
> hw/device-assignment.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 53 insertions(+), 2 deletions(-)
>
> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> index 566671c..d7a03c9 100644
> --- a/hw/device-assignment.c
> +++ b/hw/device-assignment.c
> @@ -756,6 +756,54 @@ static uint32_t calc_assigned_dev_id(uint8_t bus, uint8_t devfn)
> return (uint32_t)bus << 8 | (uint32_t)devfn;
> }
>
> +static void assign_failed_examine(AssignedDevice *dev)
> +{
> + char name[PATH_MAX], dir[PATH_MAX], driver[PATH_MAX] = {}, *ns;
> + uint16_t vendor_id, device_id;
> + int r;
> +
> + /* XXX implement multidomain */
> + sprintf(dir, "/sys/bus/pci/devices/0000:%02x:%02x.%01x/",
> + dev->host.bus, dev->host.dev, dev->host.func);
> +
> + sprintf(name, "%sdriver", dir);
> +
> + r = readlink(name, driver, sizeof(driver));
> + if ((r <= 0) || !(ns = strrchr(driver, '/')) || r >= sizeof(driver)) {
> + goto fail;
> + }
> +
> + ns++;
> +
> + if (get_real_vendor_id(dir, &vendor_id) ||
> + get_real_device_id(dir, &device_id)) {
> + goto fail;
> + }
> +
> + fprintf(stderr, "*** The driver '%s' is occupying your device "
> + "%02x:%02x.%x.\n",
> + ns, dev->host.bus, dev->host.dev, dev->host.func);
> + fprintf(stderr, "***\n");
> + fprintf(stderr, "*** You can try the following commands to free it:\n");
> + fprintf(stderr, "***\n");
> + fprintf(stderr, "*** $ echo \"%04x %04x\" > /sys/bus/pci/drivers/pci-stub/"
> + "new_id\n", vendor_id, device_id);
> + fprintf(stderr, "*** $ echo \"0000:%02x:%02x.%x\" > /sys/bus/pci/drivers/"
> + "%s/unbind\n",
> + dev->host.bus, dev->host.dev, dev->host.func, ns);
> + fprintf(stderr, "*** $ echo \"0000:%02x:%02x.%x\" > /sys/bus/pci/drivers/"
> + "pci-stub/bind\n",
> + dev->host.bus, dev->host.dev, dev->host.func);
> + fprintf(stderr, "*** $ echo \"%04x %04x\" > /sys/bus/pci/drivers/pci-stub"
> + "/remove_id\n", vendor_id, device_id);
> + fprintf(stderr, "***\n");
> +
> + return;
> +
> +fail:
> + fprintf(stderr, "Couldn't find out why.\n");
> +}
> +
> static int assign_device(AssignedDevice *dev)
> {
> struct kvm_assigned_pci_dev assigned_dev_data;
> @@ -781,9 +829,12 @@ static int assign_device(AssignedDevice *dev)
> #endif
>
> r = kvm_assign_pci_device(kvm_context, &assigned_dev_data);
> - if (r < 0)
> - fprintf(stderr, "Failed to assign device \"%s\" : %s\n",
> + if (r < 0) {
> + fprintf(stderr, "Failed to assign device \"%s\" : %s\n",
> dev->dev.qdev.id, strerror(-r));
> +
> + assign_failed_examine(dev);
> + }
> return r;
> }
>
> --
> 1.6.0.2