[Intel-gfx] [PATCH] drm/i915: Add ppgtt to GVT GEM context

[Chris Wilson]

Quoting Xiong Zhang (2018-10-18 06:40:31)
> Currently the guest couldn't boot up under GVT-g environment as the
> following call trace exists:
> [  272.504762] BUG: unable to handle kernel NULL pointer dereference at 0000000000000100
> [  272.504834] Call Trace:
> [  272.504852]  execlists_context_pin+0x2b2/0x520 [i915]
> [  272.504869]  intel_gvt_scan_and_shadow_workload+0x50/0x4d0 [i915]
> [  272.504887]  intel_vgpu_create_workload+0x3e2/0x570 [i915]
> [  272.504901]  intel_vgpu_submit_execlist+0xc0/0x2a0 [i915]
> [  272.504916]  elsp_mmio_write+0xc7/0x130 [i915]
> [  272.504930]  intel_vgpu_mmio_reg_rw+0x24a/0x4c0 [i915]
> [  272.504944]  intel_vgpu_emulate_mmio_write+0xac/0x240 [i915]
> [  272.504947]  intel_vgpu_rw+0x22d/0x270 [kvmgt]
> [  272.504949]  intel_vgpu_write+0x164/0x1f0 [kvmgt]
> 
> GVT GEM context is created by i915_gem_context_create_gvt() which
> doesn't allocate ppgtt. So GVT GEM context structure doesn't have
> a valid i915_hw_ppgtt.
> 
> This patch create ppgtt table at GVT GEM context creation, then assign
> shadow ppgtt's root table address to this ppgtt when shadow ppgtt will
> be used on GPU. So GVT GEM context has valid ppgtt address. But note
> that this ppgtt only contain valid ppgtt root table address, the table
> entry in this ppgtt structure are invalid.
> 
> Fixes:4a3d3f6785be("drm/i915: Match code to comment and enforce ppgtt for execlists")
> 
> Signed-off-by: Xiong Zhang <xiong.y.zhang at intel.com>
> Reviewed-by: Zhenyu Wang <zhenyuw at linux.intel.com>

And pushed. Thanks very much for the fixup,
-Chris