Re: [PATCH v3 3/8] drm/i915: Partition the fence registers for vGPU in i915 driver

["Yu, Zhang" <yu.c.zhang@linux.intel.com>]

On 12/12/2014 9:07 PM, Tvrtko Ursulin wrote:
>
>
> On 11/13/2014 12:02 PM, Yu Zhang wrote:
>> With Intel GVT-g, the fence registers are partitioned by multiple
>> vGPU instances in different VMs. Routine i915_gem_load() is modified
>> to reset the num_fence_regs, when the driver detects it's running in
>> a VM. And the allocated fence number is provided in PV INFO page
>> structure.
>>
>> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
>> Signed-off-by: Jike Song <jike.song@intel.com>
>> Signed-off-by: Eddie Dong <eddie.dong@intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_gem.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem.c
>> b/drivers/gpu/drm/i915/i915_gem.c
>> index 1de94cc..0c8b32e 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.c
>> +++ b/drivers/gpu/drm/i915/i915_gem.c
>> @@ -29,6 +29,7 @@
>>   #include <drm/drm_vma_manager.h>
>>   #include <drm/i915_drm.h>
>>   #include "i915_drv.h"
>> +#include "i915_vgpu.h"
>>   #include "i915_trace.h"
>>   #include "intel_drv.h"
>>   #include <linux/oom.h>
>> @@ -5014,6 +5015,10 @@ i915_gem_load(struct drm_device *dev)
>>       else
>>           dev_priv->num_fence_regs = 8;
>>
>> +    if (intel_vgpu_active(dev))
>> +        dev_priv->num_fence_regs =
>> +                I915_READ(vgtif_reg(avail_rs.fence_num));
>> +
>>       /* Initialize fence registers to zero */
>>       INIT_LIST_HEAD(&dev_priv->mm.fence_list);
>>       i915_gem_restore_fences(dev);
>>
>
> You don't need a start offset and number of allocated fences per domain?
The PV INFO structure is shared between each vgpu and host, so I guess 
this is per domain?
Not sure if I get your exact meaning. :)
>
> Regards,
>
B.R.
Yu
> Tvrtko
>
>
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