RE: [RFC PATCH v2 1/3] vfio: Use capability chains to handle device specific irq

["Zhang, Tina" <tina.zhang@intel.com>]

> -----Original Message-----
> From: intel-gvt-dev [mailto:intel-gvt-dev-bounces@lists.freedesktop.org] On
> Behalf Of kraxel@redhat.com
> Sent: Wednesday, June 5, 2019 6:10 PM
> To: Zhang, Tina <tina.zhang@intel.com>
> Cc: Tian, Kevin <kevin.tian@intel.com>; kvm@vger.kernel.org; linux-
> kernel@vger.kernel.org; Zhenyu Wang <zhenyuw@linux.intel.com>; Yuan,
> Hang <hang.yuan@intel.com>; alex.williamson@redhat.com; Lv, Zhiyuan
> <zhiyuan.lv@intel.com>; intel-gvt-dev@lists.freedesktop.org; Wang, Zhi A
> <zhi.a.wang@intel.com>
> Subject: Re: [RFC PATCH v2 1/3] vfio: Use capability chains to handle device
> specific irq
> 
>   Hi,
> 
> > > Really need to split for different planes? I'd like a
> > > VFIO_IRQ_SUBTYPE_GFX_DISPLAY_EVENT
> > > so user space can probe change for all.
> 
> > User space can choose to user different handlers according to the
> > specific event. For example, user space might not want to handle every
> > cursor event due to performance consideration. Besides, it can reduce
> > the probe times, as we don't need to probe twice to make sure if both
> > cursor plane and primary plane have been updated.
> 
> I'd suggest to use the value passed via eventfd for that, i.e. instead of
> sending "1" unconditionally send a mask of changed planes.
If there is only one eventfd working for GFX_DISPLAY, should it be  VFIO_IRQ_INFO_EVENTFD and VFIO_IRQ_INFO_AUTOMASKED? i.e. after signaling, the interrupt is automatically masked and the user space needs to unmask the line to receive new irq event.

BR,
Tina


> 
> cheers,
>   Gerd
> 
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