Re: [PATCH v4 5/6] vfio/type1: Add IOVA range capability support
From: Alex Williamson
Date: Thu Feb 22 2018 - 17:54:53 EST
On Wed, 21 Feb 2018 12:22:08 +0000
Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx> wrote:
> This allows the user-space to retrieve the supported IOVA
> range(s), excluding any reserved regions. The implementation
> is based on capability chains, added to VFIO_IOMMU_GET_INFO ioctl.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> ---
> drivers/vfio/vfio_iommu_type1.c | 88 +++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/vfio.h | 23 +++++++++++
> 2 files changed, 111 insertions(+)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 3049393..c08adb5 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1917,6 +1917,68 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
> return ret;
> }
>
> +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)
> +{
> + struct vfio_info_cap_header *header;
> + struct vfio_iommu_type1_info_cap_iova_range *iova_cap;
> +
> + header = vfio_info_cap_add(caps, size,
> + VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE, 1);
> + if (IS_ERR(header))
> + return PTR_ERR(header);
> +
> + iova_cap = container_of(header,
> + struct vfio_iommu_type1_info_cap_iova_range, header);
> + iova_cap->nr_iovas = cap_iovas->nr_iovas;
> + memcpy(iova_cap->iova_ranges, cap_iovas->iova_ranges,
> + cap_iovas->nr_iovas * sizeof(*cap_iovas->iova_ranges));
> + return 0;
> +}
> +
> +static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
> + struct vfio_info_cap *caps)
> +{
> + struct vfio_iommu_type1_info_cap_iova_range *cap_iovas;
> + struct vfio_iova *iova;
> + size_t size;
> + int iovas = 0, i = 0, ret;
> +
> + mutex_lock(&iommu->lock);
> +
> + list_for_each_entry(iova, &iommu->iova_list, list)
> + iovas++;
> +
> + if (!iovas) {
> + ret = -EINVAL;
> + goto out_unlock;
> + }
> +
> + size = sizeof(*cap_iovas) + (iovas * sizeof(*cap_iovas->iova_ranges));
> +
> + cap_iovas = kzalloc(size, GFP_KERNEL);
> + if (!cap_iovas) {
> + ret = -ENOMEM;
> + goto out_unlock;
> + }
> +
> + cap_iovas->nr_iovas = iovas;
> +
> + list_for_each_entry(iova, &iommu->iova_list, list) {
> + cap_iovas->iova_ranges[i].start = iova->start;
> + cap_iovas->iova_ranges[i].end = iova->end;
> + i++;
> + }
> +
> + ret = vfio_iommu_iova_add_cap(caps, cap_iovas, size);
> +
> + kfree(cap_iovas);
> +out_unlock:
> + mutex_unlock(&iommu->lock);
> + return ret;
> +}
> +
> static long vfio_iommu_type1_ioctl(void *iommu_data,
> unsigned int cmd, unsigned long arg)
> {
> @@ -1938,6 +2000,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
> }
> } else if (cmd == VFIO_IOMMU_GET_INFO) {
> struct vfio_iommu_type1_info info;
> + struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
> + int ret;
>
> minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);
>
> @@ -1951,6 +2015,30 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>
> info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
>
> + ret = vfio_iommu_iova_build_caps(iommu, &caps);
> + if (ret)
> + return ret;
> +
> + if (caps.size) {
> + info.flags |= VFIO_IOMMU_INFO_CAPS;
> +
> + if (info.argsz < sizeof(info) + caps.size) {
> + info.argsz = sizeof(info) + caps.size;
There's still a corner case here where the user could have provided an
argsz including cap_offset, potentially including uninitialized user
data, and it becomes more error prone not to zero that field for this
case. I'd suggest this:
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index a1ce8853caf1..d9ea69e62c46 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2105,16 +2105,25 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
} 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);
+ /* 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 (info.argsz < minsz)
return -EINVAL;
+ if (info.argsz >= capsz) {
+ minsz = capsz;
+ info.cap_offset = 0; /* output, no-recopy necessary */
+ }
+
info.flags = VFIO_IOMMU_INFO_PGSIZES;
info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
@@ -2136,13 +2145,12 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
kfree(caps.buf);
return -EFAULT;
}
- minsz = offsetofend(struct vfio_iommu_type1_info,
- cap_offset);
info.cap_offset = sizeof(info);
}
kfree(caps.buf);
}
+
return copy_to_user((void __user *)arg, &info, minsz) ?
-EFAULT : 0;
If you approve and there are no other comments, I can roll that change
into this patch as-is. Thanks,
Alex
> + } 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;
> + }
> + minsz = offsetofend(struct vfio_iommu_type1_info,
> + cap_offset);
> + info.cap_offset = sizeof(info);
> + }
> +
> + kfree(caps.buf);
> + }
> return copy_to_user((void __user *)arg, &info, minsz) ?
> -EFAULT : 0;
>
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index c743721..46b49e9 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -589,7 +589,30 @@ struct vfio_iommu_type1_info {
> __u32 argsz;
> __u32 flags;
> #define VFIO_IOMMU_INFO_PGSIZES (1 << 0) /* supported page sizes info */
> +#define VFIO_IOMMU_INFO_CAPS (1 << 1) /* Info supports caps */
> __u64 iova_pgsizes; /* Bitmap of supported page sizes */
> + __u32 cap_offset; /* Offset within info struct of first cap */
> +};
> +
> +/*
> + * The IOVA capability allows to report the valid IOVA range(s)
> + * excluding any reserved regions associated with dev group. Any dma
> + * map attempt outside the valid iova range will return error.
> + *
> + * The structures below define version 1 of this capability.
> + */
> +#define VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE 1
> +
> +struct vfio_iova_range {
> + __u64 start;
> + __u64 end;
> +};
> +
> +struct vfio_iommu_type1_info_cap_iova_range {
> + struct vfio_info_cap_header header;
> + __u32 nr_iovas;
> + __u32 reserved;
> + struct vfio_iova_range iova_ranges[];
> };
>
> #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)