Re: [PATCH v9 23/28] ARM: vITS: handle DISCARD command

[Julien Grall <julien.grall@arm.com>]

On 22/05/17 17:50, Andre Przywara wrote:
> Hi,

Hi Andre,

> On 18/05/17 15:23, Julien Grall wrote:
>> Hi Andre,
>>
>> On 11/05/17 18:53, Andre Przywara wrote:
>>> The DISCARD command drops the connection between a DeviceID/EventID
>>> and an LPI/collection pair.
>>> We mark the respective structure entries as not allocated and make
>>> sure that any queued IRQs are removed.
>>>
>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>>> ---
>>>  xen/arch/arm/vgic-v3-its.c | 24 ++++++++++++++++++++++++
>>>  1 file changed, 24 insertions(+)
>>>
>>> diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
>>> index ef7c78f..f7a8d77 100644
>>> --- a/xen/arch/arm/vgic-v3-its.c
>>> +++ b/xen/arch/arm/vgic-v3-its.c
>>> @@ -723,6 +723,27 @@ out_unlock:
>>>      return ret;
>>>  }
>>>
>>> +static int its_handle_discard(struct virt_its *its, uint64_t *cmdptr)
>>> +{
>>> +    uint32_t devid = its_cmd_get_deviceid(cmdptr);
>>> +    uint32_t eventid = its_cmd_get_id(cmdptr);
>>> +    int ret;
>>> +
>>> +    spin_lock(&its->its_lock);
>>> +
>>> +    /* Remove from the radix tree and remove the host entry. */
>>> +    ret = its_discard_event(its, devid, eventid);
>>> +
>>> +    /* Remove from the guest's ITTE. */
>>> +    if ( ret || write_itte_locked(its, devid, eventid,
>>> +                                  UNMAPPED_COLLECTION, INVALID_LPI,
>>> NULL) )
>>
>> I am not sure to fully understand this if. If ret is not NULL you
>> override it and never call write_itte_locked.
>
> If its_discard_event() succeeded above, then ret will be 0, in which
> case we call write_itte_locked(). If that returns non-zero, this is an
> error and we set ret to -1, otherwise (no error) it stays at zero.

But we want to carry the error from its_discard_event. No?

Cheers,

-- 
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel