Thanks Jan for your review comments. Please see below for my comments.
On 11/7/2017 8:40 AM, Jan Beulich wrote:
>>>> On 06.11.17 at 18:48, <[email protected]> wrote:
>> --- a/Documentation/ABI/testing/sysfs-driver-pciback
>> +++ b/Documentation/ABI/testing/sysfs-driver-pciback
>> @@ -11,3 +11,15 @@ Description:
>> #echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks
>> will allow the guest to read and write to the configuration
>> register 0x0E.
>> +
>> +What: /sys/bus/pci/drivers/pciback/do_flr
>> +Date: Nov 2017
>> +KernelVersion: 4.15
>> +Contact: [email protected]
>> +Description:
>> + An option to perform a slot or bus reset when a PCI device
>> + is owned by Xen PCI backend. Writing a string of DDDD:BB:DD.F
>> + will cause the pciback driver to perform a slot or bus reset
>> + if the device supports it. It also checks to make sure that
>> + all of the devices under the bridge are owned by Xen PCI
>> + backend.
> Why do you name this "do_flr" when you don't even try FLR, but
> go to slot or then bus reset right away.
Yes, I agree but xen toolstack has already been modified to
consume"do_flr" attribute. Hence, we are using the
function that matches with sysfs attribute.
>
>> +static int pcistub_reset_dev(struct pci_dev *dev)
>> +{
>> + struct xen_pcibk_dev_data *dev_data;
>> + bool slot = false, bus = false;
>> +
>> + if (!dev)
>> + return -EINVAL;
>> +
>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
>> +
>> + if (!pci_probe_reset_slot(dev->slot)) {
>> + slot = true;
>> + } else if (!pci_probe_reset_bus(dev->bus)) {
>> + /* We won't attempt to reset a root bridge. */
>> + if (!pci_is_root_bus(dev->bus))
>> + bus = true;
>> + }
>> +
>> + if (!bus && !slot)
>> + return -EOPNOTSUPP;
>> +
>> + if (!slot) {
>> + struct pcistub_args arg = { .dev = NULL, .dcount = 0 };
> Neither of the two initializers is really needed - just {} will do.
OK.
>
>> + /*
>> + * Make sure all devices on this bus are owned by the
>> + * PCI backend so that we can safely reset the whole bus.
>> + */
>> + pci_walk_bus(dev->bus, pcistub_search_dev, &arg);
>> +
>> + /* All devices under the bus should be part of pcistub! */
>> + if (arg.dev) {
>> + dev_err(&dev->dev, "%s device on the bus is not owned by pcistub\n",
>> + pci_name(arg.dev));
> I think "device" is superfluous here, while "the bus" could do with
> replacing by something actually identifying the bus.
I assume you want "bus" number to be printed in above msg. If yes, will do.
>
>> + return -EBUSY;
>> + }
>> +
>> + dev_dbg(&dev->dev, "pcistub owns %d devices on the bus\n",
>> + arg.dcount);
> Same here for "the bus", provided this log message is useful in the
> first place.
>
>> + }
> Aren't you missing an "else" here? Aiui in the "slot" case it may
> still be multiple devices/functions which are affected.
Good catch.� Our original code was performing same check, both for bus
and slot case
but somehow I removed it during internal review based on some comment.
I will post revised patch later this week. Thanks.
Cheers
GOVINDA
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