gvt: refine function emulate_mmio_read/write

[Zhenyu Wang]

On 2017.12.06 15:50:34 +0800, Pei Zhang wrote:
> These 2 functions are coded by multiple person in multiple patches. The
> 'return' and 'goto err' are mix-used in same place, which cause the
> function looks disorder. Unify to use only 'goto' so that the gvt lock
> is acquired in one place and released in one place.
> 
> Signed-off-by: Pei Zhang <pei.zhang at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/mmio.c | 32 ++++++++++++++------------------
>  1 file changed, 14 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/mmio.c b/drivers/gpu/drm/i915/gvt/mmio.c
> index 980ec89..24f9c2f 100644
> --- a/drivers/gpu/drm/i915/gvt/mmio.c
> +++ b/drivers/gpu/drm/i915/gvt/mmio.c
> @@ -126,13 +126,12 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
>  	unsigned int offset = 0;
>  	int ret = -EINVAL;
>  
> -
>  	if (vgpu->failsafe) {
>  		failsafe_emulate_mmio_rw(vgpu, pa, p_data, bytes, true);
>  		return 0;
>  	}
> -	mutex_lock(&gvt->lock);
>  
> +	mutex_lock(&gvt->lock);
>  	if (atomic_read(&vgpu->gtt.n_write_protected_guest_page)) {
>  		struct intel_vgpu_guest_page *gp;
>  
> @@ -146,8 +145,7 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
>  					ret, gp->gfn, pa, *(u32 *)p_data,
>  					bytes);
>  			}
> -			mutex_unlock(&gvt->lock);
> -			return ret;
> +			goto out;
>  		}
>  	}
>  
> @@ -168,14 +166,12 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
>  				p_data, bytes);
>  		if (ret)
>  			goto err;
> -		mutex_unlock(&gvt->lock);
> -		return ret;
> +		goto out;
>  	}
>  
>  	if (WARN_ON_ONCE(!reg_is_mmio(gvt, offset))) {
>  		ret = intel_gvt_hypervisor_read_gpa(vgpu, pa, p_data, bytes);
> -		mutex_unlock(&gvt->lock);
> -		return ret;
> +		goto out;
>  	}
>  
>  	if (WARN_ON(!reg_is_mmio(gvt, offset + bytes - 1)))
> @@ -191,11 +187,13 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
>  		goto err;
>  
>  	intel_gvt_mmio_set_accessed(gvt, offset);
> -	mutex_unlock(&gvt->lock);
> -	return 0;
> +	ret = 0;
> +	goto out;
> +
>  err:
>  	gvt_vgpu_err("fail to emulate MMIO read %08x len %d\n",
>  			offset, bytes);
> +out:
>  	mutex_unlock(&gvt->lock);
>  	return ret;
>  }

Please fix patch title as "drm/i915/gvt: xxx" and I think it's better
we set error reason for each fail instead of using -EINVAL everywhere
if someday we really need to check return fail reason, e.g

diff --git a/drivers/gpu/drm/i915/gvt/mmio.c b/drivers/gpu/drm/i915/gvt/mmio.c
index 4ea0feb5f04d..9759c247a65d 100644
--- a/drivers/gpu/drm/i915/gvt/mmio.c
+++ b/drivers/gpu/drm/i915/gvt/mmio.c
@@ -155,19 +155,18 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
 {
 	struct intel_gvt *gvt = vgpu->gvt;
 	unsigned int offset = 0;
-	int ret = -EINVAL;
-
+	int ret = 0;
 
 	if (vgpu->failsafe) {
 		failsafe_emulate_mmio_rw(vgpu, pa, p_data, bytes, true);
 		return 0;
 	}
+	
 	mutex_lock(&gvt->lock);
 
 	if (vgpu_gpa_is_aperture(vgpu, pa)) {
 		ret = vgpu_aperture_rw(vgpu, pa, p_data, bytes, true);
-		mutex_unlock(&gvt->lock);
-		return ret;
+		goto out;
 	}
 
 	if (atomic_read(&vgpu->gtt.n_tracked_guest_page)) {
@@ -183,56 +182,56 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
 					ret, t->gfn, pa, *(u32 *)p_data,
 					bytes);
 			}
-			mutex_unlock(&gvt->lock);
-			return ret;
+			goto out;
 		}
 	}
 
 	offset = intel_vgpu_gpa_to_mmio_offset(vgpu, pa);
 
-	if (WARN_ON(bytes > 8))
-		goto err;
+	if (WARN_ON(bytes > 8)) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	if (reg_is_gtt(gvt, offset)) {
+		ret = -EINVAL;
 		if (WARN_ON(!IS_ALIGNED(offset, 4) && !IS_ALIGNED(offset, 8)))
-			goto err;
+			goto out;
 		if (WARN_ON(bytes != 4 && bytes != 8))
-			goto err;
+			goto out;
 		if (WARN_ON(!reg_is_gtt(gvt, offset + bytes - 1)))
-			goto err;
+			goto out;
 
 		ret = intel_vgpu_emulate_gtt_mmio_read(vgpu, offset,
 				p_data, bytes);
-		if (ret)
-			goto err;
-		mutex_unlock(&gvt->lock);
-		return ret;
+		goto out;
 	}
 
 	if (WARN_ON_ONCE(!reg_is_mmio(gvt, offset))) {
 		ret = intel_gvt_hypervisor_read_gpa(vgpu, pa, p_data, bytes);
-		mutex_unlock(&gvt->lock);
-		return ret;
+		goto out;
 	}
 
-	if (WARN_ON(!reg_is_mmio(gvt, offset + bytes - 1)))
-		goto err;
+	if (WARN_ON(!reg_is_mmio(gvt, offset + bytes - 1))) {
+		ret = -EFAULT;
+		goto out;
+	}
 
 	if (!intel_gvt_mmio_is_unalign(gvt, offset)) {
-		if (WARN_ON(!IS_ALIGNED(offset, bytes)))
-			goto err;
+		if (WARN_ON(!IS_ALIGNED(offset, bytes))) {
+			ret = -EINVAL;
+			goto out;
 	}
 
 	ret = intel_vgpu_mmio_reg_rw(vgpu, offset, p_data, bytes, true);
 	if (ret < 0)
-		goto err;
+		goto out;
 
 	intel_gvt_mmio_set_accessed(gvt, offset);
-	mutex_unlock(&gvt->lock);
-	return 0;
-err:
-	gvt_vgpu_err("fail to emulate MMIO read %08x len %d\n",
-			offset, bytes);
+out:
+	if (ret)
+		gvt_vgpu_err("fail to emulate MMIO read %08x len %d\n",
+			     offset, bytes);
 	mutex_unlock(&gvt->lock);
 	return ret;
 }


-- 
Open Source Technology Center, Intel ltd.

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