Re: [PATCH v9 08/19] vfio/platform: read and write support for the device fd

[Eric Auger <eric.auger-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On 10/27/2014 07:07 PM, Antonios Motakis wrote:
> VFIO returns a file descriptor which we can use to manipulate the memory
> regions of the device. Usually, the user will mmap memory regions that are
> addressable on page boundaries, however for memory regions where this is
> not the case we cannot provide mmap functionality due to security concerns.
> For this reason we also need allow to read and write to the memory regions
some rewording needed here
> via the file descriptor. Implement this funcionality
typo

Regards

Eric
 only for MMIO regions
> of platform devices; PIO regions are not being handled at this point.
> 
> Signed-off-by: Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
> ---
>  drivers/vfio/platform/vfio_platform_common.c  | 150 ++++++++++++++++++++++++++
>  drivers/vfio/platform/vfio_platform_private.h |   1 +
>  2 files changed, 151 insertions(+)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index 82de752..e10a8d0 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -55,6 +55,10 @@ static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
>  		switch (resource_type(res)) {
>  		case IORESOURCE_MEM:
>  			vdev->regions[i].type = VFIO_PLATFORM_REGION_TYPE_MMIO;
> +			vdev->regions[i].flags |= VFIO_REGION_INFO_FLAG_READ;
> +			if (!(res->flags & IORESOURCE_READONLY))
> +				vdev->regions[i].flags |=
> +					VFIO_REGION_INFO_FLAG_WRITE;
>  			break;
>  		case IORESOURCE_IO:
>  			vdev->regions[i].type = VFIO_PLATFORM_REGION_TYPE_PIO;
> @@ -74,6 +78,11 @@ err:
>  
>  static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
>  {
> +	int i;
> +
> +	for (i = 0; i < vdev->num_regions; i++)
> +		iounmap(vdev->regions[i].ioaddr);
> +
>  	vdev->num_regions = 0;
>  	kfree(vdev->regions);
>  }
> @@ -176,15 +185,156 @@ static long vfio_platform_ioctl(void *device_data,
>  	return -ENOTTY;
>  }
>  
> +static ssize_t vfio_platform_read_mmio(struct vfio_platform_region reg,
> +				       char __user *buf, size_t count,
> +				       loff_t off)
> +{
> +	unsigned int done = 0;
> +
> +	if (!reg.ioaddr) {
> +		reg.ioaddr =
> +			ioremap_nocache(reg.addr, reg.size);
> +
> +		if (!reg.ioaddr)
> +			return -ENOMEM;
> +	}
> +
> +	while (count) {
> +		size_t filled;
> +
> +		if (count >= 4 && !(off % 4)) {
> +			u32 val;
> +
> +			val = ioread32(reg.ioaddr + off);
> +			if (copy_to_user(buf, &val, 4))
> +				goto err;
> +
> +			filled = 4;
> +		} else if (count >= 2 && !(off % 2)) {
> +			u16 val;
> +
> +			val = ioread16(reg.ioaddr + off);
> +			if (copy_to_user(buf, &val, 2))
> +				goto err;
> +
> +			filled = 2;
> +		} else {
> +			u8 val;
> +
> +			val = ioread8(reg.ioaddr + off);
> +			if (copy_to_user(buf, &val, 1))
> +				goto err;
> +
> +			filled = 1;
> +		}
> +
> +
> +		count -= filled;
> +		done += filled;
> +		off += filled;
> +		buf += filled;
> +	}
> +
> +	return done;
> +err:
> +	return -EFAULT;
> +}
> +
>  static ssize_t vfio_platform_read(void *device_data, char __user *buf,
>  				  size_t count, loff_t *ppos)
>  {
> +	struct vfio_platform_device *vdev = device_data;
> +	unsigned int index = VFIO_PLATFORM_OFFSET_TO_INDEX(*ppos);
> +	loff_t off = *ppos & VFIO_PLATFORM_OFFSET_MASK;
> +
> +	if (index >= vdev->num_regions)
> +		return -EINVAL;
> +
> +	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_READ))
> +		return -EINVAL;
> +
> +	if (vdev->regions[index].type & VFIO_PLATFORM_REGION_TYPE_MMIO)
> +		return vfio_platform_read_mmio(vdev->regions[index],
> +							buf, count, off);
> +	else if (vdev->regions[index].type & VFIO_PLATFORM_REGION_TYPE_PIO)
> +		return -EINVAL; /* not implemented */
> +
>  	return -EINVAL;
>  }
>  
> +static ssize_t vfio_platform_write_mmio(struct vfio_platform_region reg,
> +					const char __user *buf, size_t count,
> +					loff_t off)
> +{
> +	unsigned int done = 0;
> +
> +	if (!reg.ioaddr) {
> +		reg.ioaddr =
> +			ioremap_nocache(reg.addr, reg.size);
> +
> +		if (!reg.ioaddr)
> +			return -ENOMEM;
> +	}
> +
> +	while (count) {
> +		size_t filled;
> +
> +		if (count >= 4 && !(off % 4)) {
> +			u32 val;
> +
> +			if (copy_from_user(&val, buf, 4))
> +				goto err;
> +			iowrite32(val, reg.ioaddr + off);
> +
> +			filled = 4;
> +		} else if (count >= 2 && !(off % 2)) {
> +			u16 val;
> +
> +			if (copy_from_user(&val, buf, 2))
> +				goto err;
> +			iowrite16(val, reg.ioaddr + off);
> +
> +			filled = 2;
> +		} else {
> +			u8 val;
> +
> +			if (copy_from_user(&val, buf, 1))
> +				goto err;
> +			iowrite8(val, reg.ioaddr + off);
> +
> +			filled = 1;
> +		}
> +
> +		count -= filled;
> +		done += filled;
> +		off += filled;
> +		buf += filled;
> +	}
> +
> +	return done;
> +err:
> +	return -EFAULT;
> +}
> +
>  static ssize_t vfio_platform_write(void *device_data, const char __user *buf,
>  				   size_t count, loff_t *ppos)
>  {
> +	struct vfio_platform_device *vdev = device_data;
> +	unsigned int index = VFIO_PLATFORM_OFFSET_TO_INDEX(*ppos);
> +	loff_t off = *ppos & VFIO_PLATFORM_OFFSET_MASK;
> +
> +	if (index >= vdev->num_regions)
> +		return -EINVAL;
> +
> +	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_WRITE))
> +		return -EINVAL;
> +
> +	if (vdev->regions[index].type & VFIO_PLATFORM_REGION_TYPE_MMIO)
> +		return vfio_platform_write_mmio(vdev->regions[index],
> +							buf, count, off);
> +	else if (vdev->regions[index].type & VFIO_PLATFORM_REGION_TYPE_PIO)
> +		return -EINVAL; /* not implemented */
> +
>  	return -EINVAL;
>  }
>  
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index b24729f..1f251b2 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -31,6 +31,7 @@ struct vfio_platform_region {
>  	u32			type;
>  #define VFIO_PLATFORM_REGION_TYPE_MMIO	1
>  #define VFIO_PLATFORM_REGION_TYPE_PIO	2
> +	void __iomem		*ioaddr;
>  };
>  
>  struct vfio_platform_device {
>