[Intel-gfx] [RFC 6/7] drm/i915/gvt: Introduce virtual private PAT support

[Zhenyu Wang]

On 2017.08.16 21:48:24 +0800, Zhi Wang wrote:
> Yes. They will be removed after this feature checked-in.

That should be in this series too for whole picture.

> The discussion
> before is at least host should provide all collections of cache attribute so
> we will have a partial match.
>

PAT index is not enough to hold for all combinations. So can improve match
search for more details on age/location for best match. And as this is not
like other hw resource which can be assigned when vgpu create, but be setup
at vgpu run time, maybe show current ppat setting to guest e.g as hw default
for vgpu, guest can adjust for that so won't cause surprise on cache penalty?
Or at lease should output warning..

> On 08/16/17 13:18, Zhenyu Wang wrote:
> > On 2017.08.16 05:31:14 +0800, Zhi Wang wrote:
> > > Introduce PPAT MMIO handlers. The mapping between virtual PPAT indexes
> > > and physical PPAT indexes needs to be re-built after a guest write its
> > > virtual PPAT configuration.
> > > 
> > > Signed-off-by: Zhi Wang <zhi.a.wang at intel.com>
> > > ---
> > >   drivers/gpu/drm/i915/gvt/gtt.c      | 26 ++++++++++++++++++++++++++
> > >   drivers/gpu/drm/i915/gvt/gtt.h      |  4 +++-
> > >   drivers/gpu/drm/i915/gvt/handlers.c | 16 ++++++++++++++--
> > >   3 files changed, 43 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> > > index 1d7077d..6ec2a03 100644
> > > --- a/drivers/gpu/drm/i915/gvt/gtt.c
> > > +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> > > @@ -2374,6 +2374,32 @@ static void put_private_pat_index(struct intel_gvt *gvt, unsigned int index)
> > >   		set_bit(index, gtt->avail_ppat_bitmap);
> > >   }
> > > +int intel_vgpu_update_virtual_ppat(struct intel_vgpu *vgpu)
> > > +{
> > > +	struct intel_gvt *gvt = vgpu->gvt;
> > > +	struct intel_gvt_gtt_pat_ops *ops = gvt->gtt.pat_ops;
> > > +	struct intel_vgpu_gtt *gtt = &vgpu->gtt;
> > > +	unsigned int value;
> > > +	void *mem = &vgpu_vreg(vgpu, GEN8_PRIVATE_PAT_LO);
> > > +	int i;
> > > +
> > > +	if (gtt->ppat_configured) {
> > > +		/* Release all indexes first */
> > > +		for (i = 0; i < gvt->gtt.max_ppat_index; i++)
> > > +			put_private_pat_index(gvt, gtt->ppat_index[i]);
> > > +	}
> > > +
> > > +	for (i = 0; i < gvt->gtt.max_ppat_index; i++) {
> > > +		value = ops->get_pat_value(mem, i, NULL);
> > > +		gtt->ppat_index[i] = get_private_pat_index(gvt, value);
> > > +	}
> > 
> > Looks those part in 4/7 should be in this one for easier review.
> > 
> > And how to handle if really no ppat entry available? Should we define
> > some PV interface for guest on sane usage? And as with this new handler
> > for PPAT regs, should remove that from save/restore list too?
> > 
> > > +
> > > +	retire_vgpu_ppgtt_mm(vgpu);
> > > +
> > > +	gtt->ppat_configured = true;
> > > +	return 0;
> > > +}
> > > +
> > >   /**
> > >    * intel_vgpu_find_ppgtt_mm - find a PPGTT mm object
> > >    * @vgpu: a vGPU
> > > diff --git a/drivers/gpu/drm/i915/gvt/gtt.h b/drivers/gpu/drm/i915/gvt/gtt.h
> > > index a83d1f0..ab3e771 100644
> > > --- a/drivers/gpu/drm/i915/gvt/gtt.h
> > > +++ b/drivers/gpu/drm/i915/gvt/gtt.h
> > > @@ -223,7 +223,8 @@ struct intel_vgpu_gtt {
> > >   	struct list_head oos_page_list_head;
> > >   	struct list_head post_shadow_list_head;
> > >   	struct intel_vgpu_scratch_pt scratch_pt[GTT_TYPE_MAX];
> > > -
> > > +	bool ppat_configured;
> > > +	unsigned int ppat_index[MAX_PPAT_INDEX];
> > >   };
> > >   extern int intel_vgpu_init_gtt(struct intel_vgpu *vgpu);
> > > @@ -234,6 +235,7 @@ extern int intel_gvt_init_gtt(struct intel_gvt *gvt);
> > >   void intel_vgpu_reset_gtt(struct intel_vgpu *vgpu);
> > >   extern void intel_gvt_clean_gtt(struct intel_gvt *gvt);
> > > +extern int intel_vgpu_update_virtual_ppat(struct intel_vgpu *vgpu);
> > >   extern struct intel_vgpu_mm *intel_gvt_find_ppgtt_mm(struct intel_vgpu *vgpu,
> > >   		int page_table_level, void *root_entry);
> > > diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
> > > index 825abfc..e07264f 100644
> > > --- a/drivers/gpu/drm/i915/gvt/handlers.c
> > > +++ b/drivers/gpu/drm/i915/gvt/handlers.c
> > > @@ -1369,6 +1369,18 @@ static int mailbox_write(struct intel_vgpu *vgpu, unsigned int offset,
> > >   	return intel_vgpu_default_mmio_write(vgpu, offset, &value, bytes);
> > >   }
> > > +static int gen8_ppat_write(struct intel_vgpu *vgpu, unsigned int offset,
> > > +		void *p_data, unsigned int bytes)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = intel_vgpu_default_mmio_write(vgpu, offset, p_data, bytes);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	return intel_vgpu_update_virtual_ppat(vgpu);
> > > +}
> > > +
> > >   static int skl_power_well_ctl_write(struct intel_vgpu *vgpu,
> > >   		unsigned int offset, void *p_data, unsigned int bytes)
> > >   {
> > > @@ -2543,8 +2555,8 @@ static int init_broadwell_mmio_info(struct intel_gvt *gvt)
> > >   	MMIO_DH(GEN6_PCODE_MAILBOX, D_BDW_PLUS, NULL, mailbox_write);
> > > -	MMIO_D(GEN8_PRIVATE_PAT_LO, D_BDW_PLUS);
> > > -	MMIO_D(GEN8_PRIVATE_PAT_HI, D_BDW_PLUS);
> > > +	MMIO_DH(GEN8_PRIVATE_PAT_LO, D_BDW_PLUS, NULL, gen8_ppat_write);
> > > +	MMIO_DH(GEN8_PRIVATE_PAT_HI, D_BDW_PLUS, NULL, gen8_ppat_write);
> > >   	MMIO_D(GAMTARBMODE, D_BDW_PLUS);
> > > -- 
> > > 2.7.4
> > > 
> > 
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> intel-gvt-dev at lists.freedesktop.org
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