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Date: Fri, 23 Feb 2018 10:56:35 +0000
From: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
To: Alex Williamson <alex.williamson@...hat.com>
CC: "eric.auger@...hat.com" <eric.auger@...hat.com>,
"pmorel@...ux.vnet.ibm.com" <pmorel@...ux.vnet.ibm.com>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Linuxarm <linuxarm@...wei.com>,
John Garry <john.garry@...wei.com>,
"xuwei (O)" <xuwei5@...wei.com>
Subject: RE: [PATCH v4 5/6] vfio/type1: Add IOVA range capability support
> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson@...hat.com]
> Sent: Thursday, February 22, 2018 10:54 PM
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
> Cc: eric.auger@...hat.com; pmorel@...ux.vnet.ibm.com;
> kvm@...r.kernel.org; linux-kernel@...r.kernel.org; Linuxarm
> <linuxarm@...wei.com>; John Garry <john.garry@...wei.com>; xuwei (O)
> <xuwei5@...wei.com>
> Subject: Re: [PATCH v4 5/6] vfio/type1: Add IOVA range capability support
>
> On Wed, 21 Feb 2018 12:22:08 +0000
> Shameer Kolothum <shameerali.kolothum.thodi@...wei.com> 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@...wei.com>
> > ---
> > 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:
Yes, it is error prone. Thanks for spotting 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,
That looks fine to me.
Thanks,
Shameer
>
> > + } 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)
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