[PATCH 1/3] drm/i915/gvt: [small locks] use gtt lock to protect gtt list

[Zhenyu Wang]

On 2018.01.25 15:09:25 +0800, pei.zhang at intel.com wrote:
> From: Pei Zhang <pei.zhang at intel.com>
> 
> GVT gtt contains 2 oos list, and one global mm list. Use a special
> gvt->gtt_lock to protect those 3 lists.
> 
> Signed-off-by: Pei Zhang <pei.zhang at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/gtt.c | 56 ++++++++++++++++++++++++++++++++++++------
>  drivers/gpu/drm/i915/gvt/gvt.c |  1 +
>  drivers/gpu/drm/i915/gvt/gvt.h |  2 ++
>  3 files changed, 51 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index 8d5317d..f27d2fc 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -1158,7 +1158,7 @@ static int sync_oos_page(struct intel_vgpu *vgpu,
>  	return 0;
>  }
>  
> -static int detach_oos_page(struct intel_vgpu *vgpu,
> +static int detach_oos_page_locked(struct intel_vgpu *vgpu,
>  		struct intel_vgpu_oos_page *oos_page)
>  {
>  	struct intel_gvt *gvt = vgpu->gvt;
> @@ -1178,7 +1178,19 @@ static int detach_oos_page(struct intel_vgpu *vgpu,
>  	return 0;
>  }
>  
> -static int attach_oos_page(struct intel_vgpu *vgpu,
> +static int detach_oos_page(struct intel_vgpu *vgpu,
> +		struct intel_vgpu_oos_page *oos_page)
> +{
> +	int ret;
> +	struct intel_gvt *gvt = vgpu->gvt;
> +
> +	mutex_lock(&gvt->gtt_lock);
> +	ret = detach_oos_page(vgpu, oos_page);
> +	mutex_unlock(&gvt->gtt_lock);
> +	return ret;
> +}
> +
> +static int attach_oos_page_locked(struct intel_vgpu *vgpu,
>  		struct intel_vgpu_oos_page *oos_page,
>  		struct intel_vgpu_guest_page *gpt)
>  {
> @@ -1201,6 +1213,19 @@ static int attach_oos_page(struct intel_vgpu *vgpu,
>  	return 0;
>  }
>  
> +static int attach_oos_page(struct intel_vgpu *vgpu,
> +		struct intel_vgpu_oos_page *oos_page,
> +		struct intel_vgpu_guest_page *gpt)
> +{
> +	struct intel_gvt *gvt = vgpu->gvt;
> +	int ret;
> +
> +	mutex_lock(&gvt->gtt_lock);
> +	ret = attach_oos_page_locked(vgpu, oos_page, gpt);
> +	mutex_unlock(&gvt->gtt_lock);
> +	return ret;
> +}
> +
>  static int ppgtt_set_guest_page_sync(struct intel_vgpu *vgpu,
>  		struct intel_vgpu_guest_page *gpt)
>  {
> @@ -1227,19 +1252,23 @@ static int ppgtt_allocate_oos_page(struct intel_vgpu *vgpu,
>  
>  	WARN(oos_page, "shadow PPGTT page has already has a oos page\n");
>  
> +	mutex_lock(&gvt->gtt_lock);
>  	if (list_empty(&gtt->oos_page_free_list_head)) {
>  		oos_page = container_of(gtt->oos_page_use_list_head.next,
>  			struct intel_vgpu_oos_page, list);
>  		ret = ppgtt_set_guest_page_sync(vgpu, oos_page->guest_page);
>  		if (ret)
> -			return ret;
> -		ret = detach_oos_page(vgpu, oos_page);
> +			goto out;
> +		ret = detach_oos_page_locked(vgpu, oos_page);
>  		if (ret)
> -			return ret;
> +			goto out;
>  	} else
>  		oos_page = container_of(gtt->oos_page_free_list_head.next,
>  			struct intel_vgpu_oos_page, list);
> -	return attach_oos_page(vgpu, oos_page, gpt);
> +	ret = attach_oos_page_locked(vgpu, oos_page, gpt);
> +	mutex_unlock(&gvt->gtt_lock);
> +out:

Looks error path is not doing correct unlock here.

> +	return ret;
>  }
>  
>  static int ppgtt_set_guest_page_oos(struct intel_vgpu *vgpu,
> @@ -1662,7 +1691,9 @@ struct intel_vgpu_mm *intel_vgpu_create_mm(struct intel_vgpu *vgpu,
>  		ret = shadow_mm(mm);
>  		if (ret)
>  			goto fail;
> +		mutex_lock(&gvt->gtt_lock);
>  		list_add_tail(&mm->lru_list, &gvt->gtt.mm_lru_list_head);
> +		mutex_unlock(&gvt->gtt_lock);
>  	}
>  	return mm;
>  fail:
> @@ -1712,15 +1743,20 @@ int intel_vgpu_pin_mm(struct intel_vgpu_mm *mm)
>  
>  	atomic_inc(&mm->pincount);
>  	list_del_init(&mm->lru_list);
> +
> +	mutex_lock(&mm->vgpu->gvt->gtt_lock);
>  	list_add_tail(&mm->lru_list, &mm->vgpu->gvt->gtt.mm_lru_list_head);
> +	mutex_unlock(&mm->vgpu->gvt->gtt_lock);
>  	return 0;
>  }
>  
>  static int reclaim_one_mm(struct intel_gvt *gvt)
>  {
> +	int ret = 0;
>  	struct intel_vgpu_mm *mm;
>  	struct list_head *pos, *n;
>  
> +	mutex_lock(&gvt->gtt_lock);
>  	list_for_each_safe(pos, n, &gvt->gtt.mm_lru_list_head) {
>  		mm = container_of(pos, struct intel_vgpu_mm, lru_list);
>  
> @@ -1731,9 +1767,11 @@ static int reclaim_one_mm(struct intel_gvt *gvt)
>  
>  		list_del_init(&mm->lru_list);
>  		invalidate_mm(mm);
> -		return 1;
> +		ret = 1;
>  	}
> -	return 0;
> +	mutex_unlock(&gvt->gtt_lock);
> +
> +	return ret;
>  }
>  
>  /*
> @@ -2198,11 +2236,13 @@ static void clean_spt_oos(struct intel_gvt *gvt)
>  	WARN(!list_empty(&gtt->oos_page_use_list_head),
>  		"someone is still using oos page\n");
>  
> +	mutex_lock(&gvt->gtt_lock);
>  	list_for_each_safe(pos, n, &gtt->oos_page_free_list_head) {
>  		oos_page = container_of(pos, struct intel_vgpu_oos_page, list);
>  		list_del(&oos_page->list);
>  		kfree(oos_page);
>  	}
> +	mutex_unlock(&gvt->gtt_lock);
>  }
>  
>  static int setup_spt_oos(struct intel_gvt *gvt)
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
> index fac54f3..6cd4ca1 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.c
> +++ b/drivers/gpu/drm/i915/gvt/gvt.c
> @@ -379,6 +379,7 @@ int intel_gvt_init_device(struct drm_i915_private *dev_priv)
>  	idr_init(&gvt->vgpu_idr);
>  	spin_lock_init(&gvt->scheduler.mmio_context_lock);
>  	mutex_init(&gvt->lock);
> +	mutex_init(&gvt->gtt_lock);
>  	gvt->dev_priv = dev_priv;
>  
>  	init_device_info(gvt);
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
> index 7dc7a80..793224c 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.h
> +++ b/drivers/gpu/drm/i915/gvt/gvt.h
> @@ -289,6 +289,8 @@ struct intel_vgpu_type {
>  
>  struct intel_gvt {
>  	struct mutex lock;
> +	struct mutex gtt_lock;
> +
>  	struct drm_i915_private *dev_priv;
>  	struct idr vgpu_idr;	/* vGPU IDR pool */
>  
> -- 
> 2.7.4
> 

-- 
Open Source Technology Center, Intel ltd.

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