> -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > Sent: Thursday, February 22, 2018 10:54 PM > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> > Cc: eric.auger@xxxxxxxxxx; pmorel@xxxxxxxxxxxxxxxxxx; > kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Linuxarm > <linuxarm@xxxxxxxxxx>; John Garry <john.garry@xxxxxxxxxx>; xuwei (O) > <xuwei5@xxxxxxxxxx> > 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@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: 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)
