On Mon, 22 Jul 2019 05:28:35 +0000 "Lu, Kechen" <kechen.lu@xxxxxxxxx> wrote: > Hi, > > > -----Original Message----- > > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > > Sent: Saturday, July 20, 2019 12:25 AM > > To: Lu, Kechen <kechen.lu@xxxxxxxxx> > > Cc: intel-gvt-dev@xxxxxxxxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linux- > > kernel@xxxxxxxxxxxxxxx; Zhang, Tina <tina.zhang@xxxxxxxxx>; > > kraxel@xxxxxxxxxx; zhenyuw@xxxxxxxxxxxxxxx; Lv, Zhiyuan > > <zhiyuan.lv@xxxxxxxxx>; Wang, Zhi A <zhi.a.wang@xxxxxxxxx>; Tian, Kevin > > <kevin.tian@xxxxxxxxx>; Yuan, Hang <hang.yuan@xxxxxxxxx> > > Subject: Re: [RFC PATCH v4 2/6] vfio: Introduce vGPU display irq type > > > > On Thu, 18 Jul 2019 23:56:36 +0800 > > Kechen Lu <kechen.lu@xxxxxxxxx> wrote: > > > > > From: Tina Zhang <tina.zhang@xxxxxxxxx> > > > > > > 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 <tina.zhang@xxxxxxxxx> > > > --- > > > 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
