[PATCH] drm/i915/gvt: Add runtime_pm get/put to proctect MMIO accessing

[Zhenyu Wang]

On 2017.05.26 13:30:43 +0800, Chuanxiao Dong wrote:
> In some cases, GVT-g is accessing MMIO without holding runtime_pm
> and this patch can add the runtime_pm get/put to make sure when
> accessing MMIO the i915 HW is really powered on.
> 
> Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
> Signed-off-by: Chuanxiao Dong <chuanxiao.dong at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/gtt.c  | 2 ++
>  drivers/gpu/drm/i915/gvt/mmio.c | 4 ++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index c6f0077..13bfe09 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -251,8 +251,10 @@ static void write_pte64(struct drm_i915_private *dev_priv,
>  
>  	writeq(pte, addr);
>  
> +	intel_runtime_pm_get(dev_priv);
>  	I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
>  	POSTING_READ(GFX_FLSH_CNTL_GEN6);
> +	intel_runtime_pm_put(dev_priv);
>  }
>  
>  static inline struct intel_gvt_gtt_entry *gtt_get_entry64(void *pt,
> diff --git a/drivers/gpu/drm/i915/gvt/mmio.c b/drivers/gpu/drm/i915/gvt/mmio.c
> index 35f6c47..22700ae 100644
> --- a/drivers/gpu/drm/i915/gvt/mmio.c
> +++ b/drivers/gpu/drm/i915/gvt/mmio.c
> @@ -195,7 +195,9 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
>  			if (WARN_ON(mmio->offset != offset))
>  				goto err;
>  		}
> +		intel_runtime_pm_get(gvt->dev_priv);
>  		ret = mmio->read(vgpu, offset, p_data, bytes);
> +		intel_runtime_pm_put(gvt->dev_priv);
>  	} else {
>  		ret = intel_vgpu_default_mmio_read(vgpu, offset, p_data, bytes);
>  
> @@ -315,7 +317,9 @@ int intel_vgpu_emulate_mmio_write(struct intel_vgpu *vgpu, uint64_t pa,
>  		}
>  
>  		if (!ro_mask) {
> +			intel_runtime_pm_get(gvt->dev_priv);
>  			ret = mmio->write(vgpu, offset, p_data, bytes);
> +			intel_runtime_pm_put(gvt->dev_priv);
>  		} else {
>  			/* Protect RO bits like HW */
>  			u64 data = 0;

I still think we shouldn't have big hammer here as mostly our handlers
won't invoke hw, might just take care for each specific case.

-- 
Open Source Technology Center, Intel ltd.

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