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Subject: Re: [PATCH v4 01/15] vfio/type1: Refactor vfio_iommu_type1_ioctl()
To:     Liu Yi L <yi.l.liu@intel.com>, alex.williamson@redhat.com,
        baolu.lu@linux.intel.com, joro@8bytes.org
Cc:     kevin.tian@intel.com, jacob.jun.pan@linux.intel.com,
        ashok.raj@intel.com, jun.j.tian@intel.com, yi.y.sun@intel.com,
        jean-philippe@linaro.org, peterx@redhat.com, hao.wu@intel.com,
        stefanha@gmail.com, iommu@lists.linux-foundation.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1593861989-35920-1-git-send-email-yi.l.liu@intel.com>
 <1593861989-35920-2-git-send-email-yi.l.liu@intel.com>
From:   Auger Eric <eric.auger@redhat.com>
Message-ID: <0622db04-8254-8068-e00a-4681ec8686a8@redhat.com>
Date:   Mon, 6 Jul 2020 11:34:24 +0200
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Hi Yi,

On 7/4/20 1:26 PM, Liu Yi L wrote:
> This patch refactors the vfio_iommu_type1_ioctl() to use switch instead of
> if-else, and each cmd got a helper function.
command
> 
> Cc: Kevin Tian <kevin.tian@intel.com>
> CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Suggested-by: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 392 ++++++++++++++++++++++------------------
>  1 file changed, 213 insertions(+), 179 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 5e556ac..7accb59 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -2453,6 +2453,23 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
>  	return ret;
>  }
>  
> +static int vfio_iommu_type1_check_extension(struct vfio_iommu *iommu,
> +					    unsigned long arg)
> +{
> +	switch (arg) {
> +	case VFIO_TYPE1_IOMMU:
> +	case VFIO_TYPE1v2_IOMMU:
> +	case VFIO_TYPE1_NESTING_IOMMU:
> +		return 1;
> +	case VFIO_DMA_CC_IOMMU:
> +		if (!iommu)
> +			return 0;
> +		return vfio_domains_have_iommu_cache(iommu);
> +	default:
> +		return 0;
> +	}
> +}
> +
>  static int vfio_iommu_iova_add_cap(struct vfio_info_cap *caps,
>  		 struct vfio_iommu_type1_info_cap_iova_range *cap_iovas,
>  		 size_t size)
> @@ -2529,238 +2546,255 @@ static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu,
>  	return vfio_info_add_capability(caps, &cap_mig.header, sizeof(cap_mig));
>  }
>  
> -static long vfio_iommu_type1_ioctl(void *iommu_data,
> -				   unsigned int cmd, unsigned long arg)
> +static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu,
> +				     unsigned long arg)
>  {
> -	struct vfio_iommu *iommu = iommu_data;
> +	struct vfio_iommu_type1_info info;
>  	unsigned long minsz;
> +	struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
> +	unsigned long capsz;
> +	int ret;
>  
> -	if (cmd == VFIO_CHECK_EXTENSION) {
> -		switch (arg) {
> -		case VFIO_TYPE1_IOMMU:
> -		case VFIO_TYPE1v2_IOMMU:
> -		case VFIO_TYPE1_NESTING_IOMMU:
> -			return 1;
> -		case VFIO_DMA_CC_IOMMU:
> -			if (!iommu)
> -				return 0;
> -			return vfio_domains_have_iommu_cache(iommu);
> -		default:
> -			return 0;
> -		}
> -	} else if (cmd == VFIO_IOMMU_GET_INFO) {
> -		struct vfio_iommu_type1_info info;
> -		struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
> -		unsigned long capsz;
> -		int ret;
> -
> -		minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);
> +	minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);
>  
> -		/* For backward compatibility, cannot require this */
> -		capsz = offsetofend(struct vfio_iommu_type1_info, cap_offset);
> +	/* For backward compatibility, cannot require this */
> +	capsz = offsetofend(struct vfio_iommu_type1_info, cap_offset);
>  
> -		if (copy_from_user(&info, (void __user *)arg, minsz))
> -			return -EFAULT;
> +	if (copy_from_user(&info, (void __user *)arg, minsz))
> +		return -EFAULT;
>  
> -		if (info.argsz < minsz)
> -			return -EINVAL;
> +	if (info.argsz < minsz)
> +		return -EINVAL;
>  
> -		if (info.argsz >= capsz) {
> -			minsz = capsz;
> -			info.cap_offset = 0; /* output, no-recopy necessary */
> -		}
> +	if (info.argsz >= capsz) {
> +		minsz = capsz;
> +		info.cap_offset = 0; /* output, no-recopy necessary */
> +	}
>  
> -		mutex_lock(&iommu->lock);
> -		info.flags = VFIO_IOMMU_INFO_PGSIZES;
> +	mutex_lock(&iommu->lock);
> +	info.flags = VFIO_IOMMU_INFO_PGSIZES;
>  
> -		info.iova_pgsizes = iommu->pgsize_bitmap;
> +	info.iova_pgsizes = iommu->pgsize_bitmap;
>  
> -		ret = vfio_iommu_migration_build_caps(iommu, &caps);
> +	ret = vfio_iommu_migration_build_caps(iommu, &caps);
>  
> -		if (!ret)
> -			ret = vfio_iommu_iova_build_caps(iommu, &caps);
> +	if (!ret)
> +		ret = vfio_iommu_iova_build_caps(iommu, &caps);
>  
> -		mutex_unlock(&iommu->lock);
> +	mutex_unlock(&iommu->lock);
>  
> -		if (ret)
> -			return ret;
> +	if (ret)
> +		return ret;
>  
> -		if (caps.size) {
> -			info.flags |= VFIO_IOMMU_INFO_CAPS;
> +	if (caps.size) {
> +		info.flags |= VFIO_IOMMU_INFO_CAPS;
>  
> -			if (info.argsz < sizeof(info) + caps.size) {
> -				info.argsz = sizeof(info) + caps.size;
> -			} else {
> -				vfio_info_cap_shift(&caps, sizeof(info));
> -				if (copy_to_user((void __user *)arg +
> -						sizeof(info), caps.buf,
> -						caps.size)) {
> -					kfree(caps.buf);
> -					return -EFAULT;
> -				}
> -				info.cap_offset = sizeof(info);
> +		if (info.argsz < sizeof(info) + caps.size) {
> +			info.argsz = sizeof(info) + caps.size;
> +		} else {
> +			vfio_info_cap_shift(&caps, sizeof(info));
> +			if (copy_to_user((void __user *)arg +
> +					sizeof(info), caps.buf,
> +					caps.size)) {
> +				kfree(caps.buf);
> +				return -EFAULT;
>  			}
> -
> -			kfree(caps.buf);
> +			info.cap_offset = sizeof(info);
>  		}
>  
> -		return copy_to_user((void __user *)arg, &info, minsz) ?
> -			-EFAULT : 0;
> +		kfree(caps.buf);
> +	}
>  
> -	} else if (cmd == VFIO_IOMMU_MAP_DMA) {
> -		struct vfio_iommu_type1_dma_map map;
> -		uint32_t mask = VFIO_DMA_MAP_FLAG_READ |
> -				VFIO_DMA_MAP_FLAG_WRITE;
> +	return copy_to_user((void __user *)arg, &info, minsz) ?
> +			-EFAULT : 0;
> +}
>  
> -		minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);
> +static int vfio_iommu_type1_map_dma(struct vfio_iommu *iommu,
> +				    unsigned long arg)
> +{
> +	struct vfio_iommu_type1_dma_map map;
> +	unsigned long minsz;
> +	uint32_t mask = VFIO_DMA_MAP_FLAG_READ |
> +			VFIO_DMA_MAP_FLAG_WRITE;
nit: may fit into a single line? other examples below.
>  
> -		if (copy_from_user(&map, (void __user *)arg, minsz))
> -			return -EFAULT;
> +	minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);
>  
> -		if (map.argsz < minsz || map.flags & ~mask)
> -			return -EINVAL;
> +	if (copy_from_user(&map, (void __user *)arg, minsz))
> +		return -EFAULT;
>  
> -		return vfio_dma_do_map(iommu, &map);
> +	if (map.argsz < minsz || map.flags & ~mask)
> +		return -EINVAL;
>  
> -	} else if (cmd == VFIO_IOMMU_UNMAP_DMA) {
> -		struct vfio_iommu_type1_dma_unmap unmap;
> -		struct vfio_bitmap bitmap = { 0 };
> -		int ret;
> +	return vfio_dma_do_map(iommu, &map);
> +}
>  
> -		minsz = offsetofend(struct vfio_iommu_type1_dma_unmap, size);
> +static int vfio_iommu_type1_unmap_dma(struct vfio_iommu *iommu,
> +				      unsigned long arg)
> +{
> +	struct vfio_iommu_type1_dma_unmap unmap;
> +	struct vfio_bitmap bitmap = { 0 };
> +	unsigned long minsz;
> +	long ret;
int?
>  
> -		if (copy_from_user(&unmap, (void __user *)arg, minsz))
> -			return -EFAULT;
> +	minsz = offsetofend(struct vfio_iommu_type1_dma_unmap, size);
>  
> -		if (unmap.argsz < minsz ||
> -		    unmap.flags & ~VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP)
> -			return -EINVAL;
> +	if (copy_from_user(&unmap, (void __user *)arg, minsz))
> +		return -EFAULT;
>  
> -		if (unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) {
> -			unsigned long pgshift;
> +	if (unmap.argsz < minsz ||
> +	    unmap.flags & ~VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP)
> +		return -EINVAL;
>  
> -			if (unmap.argsz < (minsz + sizeof(bitmap)))
> -				return -EINVAL;
> +	if (unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) {
> +		unsigned long pgshift;
>  
> -			if (copy_from_user(&bitmap,
> -					   (void __user *)(arg + minsz),
> -					   sizeof(bitmap)))
> -				return -EFAULT;
> +		if (unmap.argsz < (minsz + sizeof(bitmap)))
> +			return -EINVAL;
>  
> -			if (!access_ok((void __user *)bitmap.data, bitmap.size))
> -				return -EINVAL;
> +		if (copy_from_user(&bitmap,
> +				   (void __user *)(arg + minsz),
> +				   sizeof(bitmap)))
> +			return -EFAULT;
>  
> -			pgshift = __ffs(bitmap.pgsize);
> -			ret = verify_bitmap_size(unmap.size >> pgshift,
> -						 bitmap.size);
> -			if (ret)
> -				return ret;
> -		}
> +		if (!access_ok((void __user *)bitmap.data, bitmap.size))
> +			return -EINVAL;
>  
> -		ret = vfio_dma_do_unmap(iommu, &unmap, &bitmap);
> +		pgshift = __ffs(bitmap.pgsize);
> +		ret = verify_bitmap_size(unmap.size >> pgshift,
> +					 bitmap.size);
>  		if (ret)
>  			return ret;
> +	}
> +
> +	ret = vfio_dma_do_unmap(iommu, &unmap, &bitmap);
> +	if (ret)
> +		return ret;
>  
> -		return copy_to_user((void __user *)arg, &unmap, minsz) ?
> +	return copy_to_user((void __user *)arg, &unmap, minsz) ?
>  			-EFAULT : 0;
> -	} else if (cmd == VFIO_IOMMU_DIRTY_PAGES) {
> -		struct vfio_iommu_type1_dirty_bitmap dirty;
> -		uint32_t mask = VFIO_IOMMU_DIRTY_PAGES_FLAG_START |
> -				VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP |
> -				VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP;
> -		int ret = 0;
> +}
>  
> -		if (!iommu->v2)
> -			return -EACCES;
> +static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
> +					unsigned long arg)
> +{
> +	struct vfio_iommu_type1_dirty_bitmap dirty;
> +	uint32_t mask = VFIO_IOMMU_DIRTY_PAGES_FLAG_START |
> +			VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP |
> +			VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP;
> +	unsigned long minsz;
> +	int ret = 0;
>  
> -		minsz = offsetofend(struct vfio_iommu_type1_dirty_bitmap,
> -				    flags);
> +	if (!iommu->v2)
> +		return -EACCES;
>  
> -		if (copy_from_user(&dirty, (void __user *)arg, minsz))
> -			return -EFAULT;
> +	minsz = offsetofend(struct vfio_iommu_type1_dirty_bitmap,
> +			    flags);
single line?
>  
> -		if (dirty.argsz < minsz || dirty.flags & ~mask)
> -			return -EINVAL;
> +	if (copy_from_user(&dirty, (void __user *)arg, minsz))
> +		return -EFAULT;
> +
> +	if (dirty.argsz < minsz || dirty.flags & ~mask)
> +		return -EINVAL;
> +
> +	/* only one flag should be set at a time */
> +	if (__ffs(dirty.flags) != __fls(dirty.flags))
> +		return -EINVAL;
> +
> +	if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_START) {
> +		size_t pgsize;
>  
> -		/* only one flag should be set at a time */
> -		if (__ffs(dirty.flags) != __fls(dirty.flags))
> +		mutex_lock(&iommu->lock);
> +		pgsize = 1 << __ffs(iommu->pgsize_bitmap);
> +		if (!iommu->dirty_page_tracking) {
> +			ret = vfio_dma_bitmap_alloc_all(iommu, pgsize);
> +			if (!ret)
> +				iommu->dirty_page_tracking = true;
> +		}
> +		mutex_unlock(&iommu->lock);
> +		return ret;
> +	} else if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP) {
> +		mutex_lock(&iommu->lock);
> +		if (iommu->dirty_page_tracking) {
> +			iommu->dirty_page_tracking = false;
> +			vfio_dma_bitmap_free_all(iommu);
> +		}
> +		mutex_unlock(&iommu->lock);
> +		return 0;
> +	} else if (dirty.flags &
> +			 VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP) {
single line?
> +		struct vfio_iommu_type1_dirty_bitmap_get range;
> +		unsigned long pgshift;
> +		size_t data_size = dirty.argsz - minsz;
> +		size_t iommu_pgsize;
> +
> +		if (!data_size || data_size < sizeof(range))
>  			return -EINVAL;
>  
> -		if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_START) {
> -			size_t pgsize;
> +		if (copy_from_user(&range, (void __user *)(arg + minsz),
> +				   sizeof(range)))
> +			return -EFAULT;
>  
> -			mutex_lock(&iommu->lock);
> -			pgsize = 1 << __ffs(iommu->pgsize_bitmap);
> -			if (!iommu->dirty_page_tracking) {
> -				ret = vfio_dma_bitmap_alloc_all(iommu, pgsize);
> -				if (!ret)
> -					iommu->dirty_page_tracking = true;
> -			}
> -			mutex_unlock(&iommu->lock);
> +		if (range.iova + range.size < range.iova)
> +			return -EINVAL;
> +		if (!access_ok((void __user *)range.bitmap.data,
> +			       range.bitmap.size))
> +			return -EINVAL;
> +
> +		pgshift = __ffs(range.bitmap.pgsize);
> +		ret = verify_bitmap_size(range.size >> pgshift,
> +					 range.bitmap.size);
> +		if (ret)
>  			return ret;
> -		} else if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP) {
> -			mutex_lock(&iommu->lock);
> -			if (iommu->dirty_page_tracking) {
> -				iommu->dirty_page_tracking = false;
> -				vfio_dma_bitmap_free_all(iommu);
> -			}
> -			mutex_unlock(&iommu->lock);
> -			return 0;
> -		} else if (dirty.flags &
> -				 VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP) {
idem
> -			struct vfio_iommu_type1_dirty_bitmap_get range;
> -			unsigned long pgshift;
> -			size_t data_size = dirty.argsz - minsz;
> -			size_t iommu_pgsize;
> -
> -			if (!data_size || data_size < sizeof(range))
> -				return -EINVAL;
> -
> -			if (copy_from_user(&range, (void __user *)(arg + minsz),
> -					   sizeof(range)))
> -				return -EFAULT;
>  
> -			if (range.iova + range.size < range.iova)
> -				return -EINVAL;
> -			if (!access_ok((void __user *)range.bitmap.data,
> -				       range.bitmap.size))
> -				return -EINVAL;
> +		mutex_lock(&iommu->lock);
>  
> -			pgshift = __ffs(range.bitmap.pgsize);
> -			ret = verify_bitmap_size(range.size >> pgshift,
> -						 range.bitmap.size);
> -			if (ret)
> -				return ret;
> +		iommu_pgsize = (size_t)1 << __ffs(iommu->pgsize_bitmap);
>  
> -			mutex_lock(&iommu->lock);
> +		/* allow only smallest supported pgsize */
> +		if (range.bitmap.pgsize != iommu_pgsize) {
> +			ret = -EINVAL;
> +			goto out_unlock;
> +		}
> +		if (range.iova & (iommu_pgsize - 1)) {
> +			ret = -EINVAL;
> +			goto out_unlock;
> +		}
> +		if (!range.size || range.size & (iommu_pgsize - 1)) {
> +			ret = -EINVAL;
> +			goto out_unlock;
> +		}
>  
> -			iommu_pgsize = (size_t)1 << __ffs(iommu->pgsize_bitmap);
> +		if (iommu->dirty_page_tracking)
> +			ret = vfio_iova_dirty_bitmap(range.bitmap.data,
> +					iommu, range.iova, range.size,
> +					range.bitmap.pgsize);
> +		else
> +			ret = -EINVAL;
> +out_unlock:
> +		mutex_unlock(&iommu->lock);
>  
> -			/* allow only smallest supported pgsize */
> -			if (range.bitmap.pgsize != iommu_pgsize) {
> -				ret = -EINVAL;
> -				goto out_unlock;
> -			}
> -			if (range.iova & (iommu_pgsize - 1)) {
> -				ret = -EINVAL;
> -				goto out_unlock;
> -			}
> -			if (!range.size || range.size & (iommu_pgsize - 1)) {
> -				ret = -EINVAL;
> -				goto out_unlock;
> -			}
> +		return ret;
> +	}
>  
> -			if (iommu->dirty_page_tracking)
> -				ret = vfio_iova_dirty_bitmap(range.bitmap.data,
> -						iommu, range.iova, range.size,
> -						range.bitmap.pgsize);
> -			else
> -				ret = -EINVAL;
> -out_unlock:
> -			mutex_unlock(&iommu->lock);
> +	return -EINVAL;
> +}
>  
> -			return ret;
> -		}
> +static long vfio_iommu_type1_ioctl(void *iommu_data,
> +				   unsigned int cmd, unsigned long arg)
> +{
> +	struct vfio_iommu *iommu = iommu_data;
> +
> +	switch (cmd) {
> +	case VFIO_CHECK_EXTENSION:
> +		return vfio_iommu_type1_check_extension(iommu, arg);
> +	case VFIO_IOMMU_GET_INFO:
> +		return vfio_iommu_type1_get_info(iommu, arg);
> +	case VFIO_IOMMU_MAP_DMA:
> +		return vfio_iommu_type1_map_dma(iommu, arg);
> +	case VFIO_IOMMU_UNMAP_DMA:
> +		return vfio_iommu_type1_unmap_dma(iommu, arg);
> +	case VFIO_IOMMU_DIRTY_PAGES:
> +		return vfio_iommu_type1_dirty_pages(iommu, arg);
default:
	return -ENOTTY; ?
>  	}
>  
>  	return -ENOTTY;
> 

Besides
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric