[PATCH] drm/i915/gvt: Handle GEN9_WM_CHICKEN3 with F_CMD_ACCESS for BXT.

[Colin Xu]

On 8/16/18 2:49 PM, Zhenyu Wang wrote:
> On 2018.08.16 12:25:28 +0800, Colin Xu wrote:
>> Recent patch introduce strict check on scanning cmd:
>> Commit 8d458ea0ec33 ("drm/i915/gvt: return error on cmd access")
>>
>> On BXT, i915 applies WaClearHIZ_WM_CHICKEN3 which will program
>> the reg 0x5588 by LRI, so we should handle GEN9_WM_CHICKEN3 with
>> F_CMD_ACCESS, also add F_MODE_MASK since it's mode mask reg.
>>
> Could you elaborate more on the symptom that this one fixes? As
> we have more strict cmd scan detection, does this cause guest failure or etc.?

Before 8d458ea0ec33, if cmd_reg_handler() checks that a cmd access a mmio
that not marked as F_CMD_ACCESS, it simply returns 0 and log an error. Now it
will return -EBADRQC which will cause the workload fail to submit. Since
GEN9_WM_CHICKEN3 is accessed at wa ctx init, vgpu will fail to start on BXT.

>> Signed-off-by: Colin Xu <colin.xu at intel.com>
>> ---
>>   drivers/gpu/drm/i915/gvt/handlers.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
>> index cf2a4020949d..e32a69fabda3 100644
>> --- a/drivers/gpu/drm/i915/gvt/handlers.c
>> +++ b/drivers/gpu/drm/i915/gvt/handlers.c
>> @@ -3205,6 +3205,8 @@ static int init_bxt_mmio_info(struct intel_gvt *gvt)
>>   	MMIO_D(GEN8_L3SQCREG1, D_BXT);
>>   
>>   	MMIO_DFH(GEN9_CTX_PREEMPT_REG, D_BXT, F_CMD_ACCESS, NULL, NULL);
>> +	MMIO_DFH(GEN9_WM_CHICKEN3, D_BXT,
>> +		 F_MODE_MASK | F_CMD_ACCESS, NULL, NULL);
>>   
>>   	return 0;
>>   }
>> -- 
>> 2.18.0
>>
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-- 
Best Regards,
Colin Xu