On Mon, 22 Jul 2019 05:28:35 +0000 "Lu, Kechen" <[email protected]> wrote:
> Hi, > > > -----Original Message----- > > From: Alex Williamson [mailto:[email protected]] > > Sent: Saturday, July 20, 2019 12:25 AM > > To: Lu, Kechen <[email protected]> > > Cc: [email protected]; [email protected]; linux- > > [email protected]; Zhang, Tina <[email protected]>; > > [email protected]; [email protected]; Lv, Zhiyuan > > <[email protected]>; Wang, Zhi A <[email protected]>; Tian, Kevin > > <[email protected]>; Yuan, Hang <[email protected]> > > Subject: Re: [RFC PATCH v4 2/6] vfio: Introduce vGPU display irq type > > > > On Thu, 18 Jul 2019 23:56:36 +0800 > > Kechen Lu <[email protected]> wrote: > > > > > From: Tina Zhang <[email protected]> > > > > > > Introduce vGPU specific irq type VFIO_IRQ_TYPE_GFX, and > > > VFIO_IRQ_SUBTYPE_GFX_DISPLAY_IRQ as the subtype for vGPU display > > > > > > Signed-off-by: Tina Zhang <[email protected]> > > > --- > > > include/uapi/linux/vfio.h | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > > > index be6adab4f759..df28b17a6e2e 100644 > > > --- a/include/uapi/linux/vfio.h > > > +++ b/include/uapi/linux/vfio.h > > > @@ -469,6 +469,9 @@ struct vfio_irq_info_cap_type { > > > __u32 subtype; /* type specific */ > > > }; > > > > > > +#define VFIO_IRQ_TYPE_GFX (1) > > > +#define VFIO_IRQ_SUBTYPE_GFX_DISPLAY_IRQ (1) > > > + > > > > Please include a description defining exactly what this IRQ is intended to > > signal. > > For instance, if another vGPU vendor wanted to implement this in their > > driver > > and didn't have the QEMU code for reference to what it does with the IRQ, > > what > > would they need to know? Thanks, > > > > Alex > > > > Yes, that makes more sense. I'll add the description for it at next version > patch. > > BTW, may I have one more question? In the current design ideas, we > partitioned > the vGPU display eventfd counted 8-byte value into at most 8 events to > deliver > multiple display events, so we need different increasement counter value to > differentiate the events. As this is the exposed thing the QEMU has to know, > we > plan adds a macro here VFIO_IRQ_SUBTYPE_GFX_DISPLAY_EVENTFD_BASE_SHIFT to > make sure the partitions shift in 1 byte, does it make sense putting here? > Looking > forward to your and Gerd's comments. Thanks! Couldn't you expose this as another capability within the IRQ_INFO return data? If you were to define it as a macro, I assume that means it would be hard coded, in which case this probably becomes an Intel specific IRQ, rather than what appears to be framed as a generic graphics IRQ extension. A new capability could instead allow the vendor to specify their own value, where we could define how userspace should interpret and make use of this value. Thanks, Alex
