[PATCH v1 2/2] drm/i915: enable vGPU 48bit full PPGTT support

[Zhang, Tina]

> -----Original Message-----
> From: intel-gvt-dev [mailto:intel-gvt-dev-bounces at lists.freedesktop.org] On
> Behalf Of Zhenyu Wang
> Sent: Friday, May 5, 2017 3:25 PM
> To: Zhang, Tina <tina.zhang at intel.com>
> Cc: intel-gvt-dev at lists.freedesktop.org
> Subject: Re: [PATCH v1 2/2] drm/i915: enable vGPU 48bit full PPGTT support
> 
> On 2017.05.05 06:27:58 +0000, Zhang, Tina wrote:
> >
> >
> > > -----Original Message-----
> > > From: Zhenyu Wang [mailto:zhenyuw at linux.intel.com]
> > > Sent: Friday, May 5, 2017 12:55 PM
> > > To: Zhang, Tina <tina.zhang at intel.com>
> > > Cc: intel-gvt-dev at lists.freedesktop.org
> > > Subject: Re: [PATCH v1 2/2] drm/i915: enable vGPU 48bit full PPGTT
> support
> > >
> > > On 2017.05.04 17:35:10 +0800, Tina Zhang wrote:
> > > > This patch is to enable the vGPU 48bit full ppgtt support.
> > > >
> > > > Signed-off-by: Tina Zhang <tina.zhang at intel.com>
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c
> > > b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > > > index 8bab4ae..92df4c4 100644
> > > > --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> > > > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > > > @@ -141,12 +141,6 @@ int intel_sanitize_enable_ppgtt(struct
> > > drm_i915_private *dev_priv,
> > > >  	has_full_ppgtt = dev_priv->info.has_full_ppgtt;
> > > >  	has_full_48bit_ppgtt = dev_priv->info.has_full_48bit_ppgtt;
> > > >
> > > > -	if (intel_vgpu_active(dev_priv)) {
> > > > -		/* emulation is too hard */
> > > > -		has_full_ppgtt = false;
> > > > -		has_full_48bit_ppgtt = false;
> > > > -	}
> > > > -
> > > >  	if (!has_aliasing_ppgtt)
> > > >  		return 0;
> > > >
> > >
> > > What if you run new kernel with this change on older gvt kernel?
> > The issue may come out again which may lead to GPU hang.
> >
> > > We need compat check.
> > Do you mean we need a flag in pvinfo to tell the guest whether enabling the
> full ppgtt feature is allowed?
> >
> 
> yeah, I think we need a formal feature flag in pvinfo, e.g full ppgtt, guc/huc, etc.
Oh. I'm thinking, for full ppgtt, maybe we can make the thing easier by combining the two patches into one. After all, the Linux guest full ppgtt is blocked by an issue. Here we fixed the issue, and make the ppgtt good to go. So, if there is only one patch for this issue, ppgtt won't have the compatibility problem.

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