linux-kernel - Re: [PATCH 5/9] vfio/fsl-mc: Allow userspace to MMAP fsl-mc device MMIO regions

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Message-ID: <8610166d-fa6c-c324-be8e-c5e6df41dcc6@nxp.com>
Date:   Tue, 24 Mar 2020 12:08:27 +0200
From:   Laurentiu Tudor <laurentiu.tudor@....com>
To:     Diana Craciun <diana.craciun@....nxp.com>, kvm@...r.kernel.org,
        alex.williamson@...hat.com, linux-arm-kernel@...ts.infradead.org,
        bharatb.yadav@...il.com
Cc:     linux-kernel@...r.kernel.org,
        Bharat Bhushan <Bharat.Bhushan@....com>
Subject: Re: [PATCH 5/9] vfio/fsl-mc: Allow userspace to MMAP fsl-mc device
 MMIO regions



On 3/23/2020 7:19 PM, Diana Craciun wrote:
> Allow userspace to mmap device regions for direct access of
> fsl-mc devices.
> 
> Signed-off-by: Bharat Bhushan <Bharat.Bhushan@....com>
> Signed-off-by: Diana Craciun <diana.craciun@....nxp.com>
> ---
>  drivers/vfio/fsl-mc/vfio_fsl_mc.c         | 64 ++++++++++++++++++++++-
>  drivers/vfio/fsl-mc/vfio_fsl_mc_private.h |  2 +
>  2 files changed, 64 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> index 094df3aa3710..6625b7cb0a3e 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> @@ -31,7 +31,11 @@ static int vfio_fsl_mc_regions_init(struct vfio_fsl_mc_device *vdev)
>  
>  		vdev->regions[i].addr = res->start;
>  		vdev->regions[i].size = PAGE_ALIGN((resource_size(res)));
> -		vdev->regions[i].flags = 0;
> +		vdev->regions[i].flags = VFIO_REGION_INFO_FLAG_MMAP;
> +		vdev->regions[i].flags |= VFIO_REGION_INFO_FLAG_READ;
> +		if (!(mc_dev->regions[i].flags & IORESOURCE_READONLY))
> +			vdev->regions[i].flags |= VFIO_REGION_INFO_FLAG_WRITE;
> +		vdev->regions[i].type = mc_dev->regions[i].flags & IORESOURCE_BITS;
>  	}
>  
>  	vdev->num_regions = mc_dev->obj_desc.region_count;
> @@ -163,9 +167,65 @@ static ssize_t vfio_fsl_mc_write(void *device_data, const char __user *buf,
>  	return -EINVAL;
>  }
>  
> +static int vfio_fsl_mc_mmap_mmio(struct vfio_fsl_mc_region region,
> +				 struct vm_area_struct *vma)
> +{
> +	u64 size = vma->vm_end - vma->vm_start;
> +	u64 pgoff, base;
> +
> +	pgoff = vma->vm_pgoff &
> +		((1U << (VFIO_FSL_MC_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
> +	base = pgoff << PAGE_SHIFT;
> +
> +	if (region.size < PAGE_SIZE || base + size > region.size)
> +		return -EINVAL;
> +
> +	if (!(region.type & VFIO_DPRC_REGION_CACHEABLE))
> +		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> +
> +	vma->vm_pgoff = (region.addr >> PAGE_SHIFT) + pgoff;
> +
> +	return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
> +			       size, vma->vm_page_prot);
> +}
> +
>  static int vfio_fsl_mc_mmap(void *device_data, struct vm_area_struct *vma)
>  {
> -	return -EINVAL;
> +	struct vfio_fsl_mc_device *vdev = device_data;
> +	struct fsl_mc_device *mc_dev = vdev->mc_dev;
> +	unsigned long size, addr;
> +	int index;
> +
> +	index = vma->vm_pgoff >> (VFIO_FSL_MC_OFFSET_SHIFT - PAGE_SHIFT);
> +
> +	if (vma->vm_end < vma->vm_start)
> +		return -EINVAL;
> +	if (vma->vm_start & ~PAGE_MASK)
> +		return -EINVAL;
> +	if (vma->vm_end & ~PAGE_MASK)
> +		return -EINVAL;
> +	if (!(vma->vm_flags & VM_SHARED))
> +		return -EINVAL;
> +	if (index >= vdev->num_regions)
> +		return -EINVAL;
> +
> +	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_MMAP))
> +		return -EINVAL;
> +
> +	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_READ)
> +			&& (vma->vm_flags & VM_READ))
> +		return -EINVAL;
> +
> +	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_WRITE)
> +			&& (vma->vm_flags & VM_WRITE))
> +		return -EINVAL;
> +
> +	addr = vdev->regions[index].addr;
> +	size = vdev->regions[index].size;

These seem unused?

---
Best Regards, Laurentiu

> +	vma->vm_private_data = mc_dev;
> +
> +	return vfio_fsl_mc_mmap_mmio(vdev->regions[index], vma);
>  }
>  
>  static int vfio_fsl_mc_init_device(struct vfio_fsl_mc_device *vdev)
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> index 764e2cf2c70d..e2a0ccdd8242 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> @@ -15,6 +15,8 @@
>  #define VFIO_FSL_MC_INDEX_TO_OFFSET(index)	\
>  	((u64)(index) << VFIO_FSL_MC_OFFSET_SHIFT)
>  
> +#define VFIO_DPRC_REGION_CACHEABLE	0x00000001
> +
>  struct vfio_fsl_mc_region {
>  	u32			flags;
>  	u32			type;
>