[PATCH v1 3/5] drm/i915/gvt: GVTg support context submission pvmmio optimization

[Zhang, Xiaolin]

On 11/05/2018 06:03 PM, Zhenyu Wang wrote:
> On 2018.11.05 17:20:47 +0800, Xiaolin Zhang wrote:
>> implemented context submission pvmmio optimizaiton with GVTg.
>>
>> GVTg to read context submission data (elsp_data) from the shared_page
>> directly without trap cost to improve guest GPU peformrnace.
>>
>> v1: rebase
>> v0: RFC
>>
>> Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
>> Cc: Zhi Wang <zhi.a.wang at intel.com>
>> Cc: Min He<min.he at intel.com>
>> Cc: Fei Jiang <fei.jiang at intel.com>
>> Cc: Zhipeng Gong <zhipeng.gong at intel.com>
>> Cc: Hang Yuan <hang.yuan at intel.com>
>> Cc: Zhiyuan Lv <zhiyuan.lv at intel.com>
>> Signed-off-by: Xiaolin Zhang <xiaolin.zhang at intel.com>
>> ---
>>  drivers/gpu/drm/i915/gvt/handlers.c | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
>> index bf14c66..cd3b602 100644
>> --- a/drivers/gpu/drm/i915/gvt/handlers.c
>> +++ b/drivers/gpu/drm/i915/gvt/handlers.c
>> @@ -1667,6 +1667,8 @@ static int elsp_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
>>  	int ring_id = intel_gvt_render_mmio_to_ring_id(vgpu->gvt, offset);
>>  	struct intel_vgpu_execlist *execlist;
>>  	u32 data = *(u32 *)p_data;
>> +	u32 elsp_data[4];
>> +	u32 elsp_data_off;
>>  	int ret = 0;
>>  
>>  	if (WARN_ON(ring_id < 0 || ring_id >= I915_NUM_ENGINES))
>> @@ -1674,6 +1676,16 @@ static int elsp_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
>>  
>>  	execlist = &vgpu->submission.execlist[ring_id];
>>  
>> +	if (VGPU_PVMMIO(vgpu) & PVMMIO_ELSP_SUBMIT) {
>> +		elsp_data_off = offsetof(struct gvt_shared_page, elsp_data);
>> +		intel_gvt_read_shared_page(vgpu, elsp_data_off, &elsp_data, 16);
>> +		execlist->elsp_dwords.data[3] = elsp_data[0];
>> +		execlist->elsp_dwords.data[2] = elsp_data[1];
>> +		execlist->elsp_dwords.data[1] = elsp_data[2];
>> +		execlist->elsp_dwords.data[0] = data;
>> +		return intel_vgpu_submit_execlist(vgpu, ring_id);
>> +	}
> I think we still need to do more check, e.g if ctx address is in valid vgpu range, etc?
I think your concern to check input data eslp_datt[4], but elsp_data[4]
store the context descriptor, not ctx address.  so I am not sure is
there any mechanism to validate context descriptor.
>
>> +
>>  	execlist->elsp_dwords.data[3 - execlist->elsp_dwords.index] = data;
>>  	if (execlist->elsp_dwords.index == 3) {
>>  		ret = intel_vgpu_submit_execlist(vgpu, ring_id);
>> -- 
>> 2.7.4
>>