[PATCH] drm/i915/gvt: Stop initializing pvinfo through reading mmio

[Zhenyu Wang]

On 2019.11.05 03:16:16 +0000, Zhang, Tina wrote:
> > -----Original Message-----
> > From: Zhenyu Wang <zhenyuw at linux.intel.com>
> > Sent: Tuesday, November 5, 2019 10:54 AM
> > To: Zhang, Tina <tina.zhang at intel.com>
> > Cc: intel-gvt-dev at lists.freedesktop.org
> > Subject: Re: [PATCH] drm/i915/gvt: Stop initializing pvinfo through reading
> > mmio
> > 
> > On 2019.11.04 13:31:48 +0800, Tina Zhang wrote:
> > > The region of pvinfo is reserved for communication between a VMM and
> > > the GPU driver executing on a virtual machine. HW doesn't have any
> > > backing mmio store support for the pvinfo region, thus accessing to
> > > this range through MMIO read/write from host side is forbidden which
> > > is regarded as unclaimed register access.
> > >
> > > This patch leaves pvinfo range be initialized with zero.
> > >
> > > Signed-off-by: Tina Zhang <tina.zhang at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/gvt/handlers.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/i915/gvt/handlers.c
> > > b/drivers/gpu/drm/i915/gvt/handlers.c
> > > index afd7f66bdc2d..bd12af349123 100644
> > > --- a/drivers/gpu/drm/i915/gvt/handlers.c
> > > +++ b/drivers/gpu/drm/i915/gvt/handlers.c
> > > @@ -3420,6 +3420,10 @@ int intel_gvt_for_each_tracked_mmio(struct
> > intel_gvt *gvt,
> > >  	}
> > >
> > >  	for (i = 0; i < gvt->mmio.num_mmio_block; i++, block++) {
> > > +		/* pvinfo data doesn't come from hw mmio */
> > > +		if (i915_mmio_reg_offset(block->offset) ==
> > VGT_PVINFO_PAGE)
> > > +			continue;
> > 
> > Equal to remove PVINFO in mmio_block list? Could we just remove it there
> > instead of this special case?
> Commit 65f9f6feb wanted it to be kept in in mmio_block for performance consideration. Thanks.
> 

oh, my bad, we need to handle PVINFO access anyway, not just for initial state.

Reviewed-by: Zhenyu Wang <zhenyuw at linux.intel.com>

> > > +
> > >  		for (j = 0; j < block->size; j += 4) {
> > >  			ret = handler(gvt,
> > >  				      i915_mmio_reg_offset(block->offset) + j,
> > > --
> > > 2.17.1
> > >
> > 
> > --
> > Open Source Technology Center, Intel ltd.
> > 
> > $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827

-- 
Open Source Technology Center, Intel ltd.

$gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827
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