Messages in this thread | | | Date | Fri, 4 Aug 2023 09:59:11 +0800 | Subject | Re: [PATCH v5 3/4] iommufd: Add IOMMU_GET_HW_INFO | From | Baolu Lu <> |
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On 2023/8/3 22:31, Yi Liu wrote: > Under nested IOMMU translation, userspace owns the stage-1 translation > table (e.g. the stage-1 page table of Intel VT-d or the context table > of ARM SMMUv3, and etc.). Stage-1 translation tables are vendor specific, > and need to be compatiable with the underlying IOMMU hardware. Hence,
compatible
> userspace should know the IOMMU hardware capability before creating and > configuring the stage-1 translation table to kernel. > > This adds IOMMU_GET_HW_INFO ioctl to query the IOMMU hardware information > (a.k.a capability) for a given device. The returned data is vendor specific, > userspace needs to decode it with the structure mapped by the @out_data_type > field. > > As only physical devices have IOMMU hardware, so this will return error > if the given device is not a physical device. > > Co-developed-by: Nicolin Chen <nicolinc@nvidia.com> > Signed-off-by: Nicolin Chen <nicolinc@nvidia.com> > Signed-off-by: Yi Liu <yi.l.liu@intel.com> > --- > drivers/iommu/iommufd/main.c | 79 ++++++++++++++++++++++++++++++++++++ > include/uapi/linux/iommufd.h | 36 ++++++++++++++++ > 2 files changed, 115 insertions(+) > > diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c > index 94c498b8fdf6..a0302bcaa97c 100644 > --- a/drivers/iommu/iommufd/main.c > +++ b/drivers/iommu/iommufd/main.c > @@ -17,6 +17,7 @@ > #include <linux/bug.h> > #include <uapi/linux/iommufd.h> > #include <linux/iommufd.h> > +#include "../iommu-priv.h" > > #include "io_pagetable.h" > #include "iommufd_private.h" > @@ -177,6 +178,81 @@ static int iommufd_destroy(struct iommufd_ucmd *ucmd) > return 0; > } > > +static int iommufd_zero_fill_user(void __user *ptr, size_t bytes) > +{ > + int index = 0; > + > + for (; index < bytes; index++) { > + if (put_user(0, (uint8_t __user *)(ptr + index))) > + return -EFAULT; > + } > + return 0; > +} > + > +static int iommufd_get_hw_info(struct iommufd_ucmd *ucmd) > +{ > + u32 hw_info_type = IOMMU_HW_INFO_TYPE_NONE; > + struct iommu_hw_info *cmd = ucmd->cmd; > + unsigned int length = 0, data_len; > + struct iommufd_device *idev; > + const struct iommu_ops *ops; > + void __user *user_ptr; > + void *data = NULL; > + int rc = 0; > + > + if (cmd->flags || cmd->__reserved || !cmd->data_len) > + return -EOPNOTSUPP; > + > + idev = iommufd_get_device(ucmd, cmd->dev_id); > + if (IS_ERR(idev)) > + return PTR_ERR(idev); > + > + user_ptr = u64_to_user_ptr(cmd->data_ptr); > + > + ops = dev_iommu_ops(idev->dev); > + if (!ops->hw_info) > + goto done; > + > + data = ops->hw_info(idev->dev, &data_len, &hw_info_type); > + if (IS_ERR(data)) { > + rc = PTR_ERR(data); > + goto out_err;
Can kfree() handle a ERR_PTR input? I am afraid not,
/** * kfree - free previously allocated memory * @object: pointer returned by kmalloc() or kmem_cache_alloc() * * If @object is NULL, no operation is performed. */ void kfree(const void *object) { struct folio *folio; struct slab *slab; struct kmem_cache *s;
trace_kfree(_RET_IP_, object);
if (unlikely(ZERO_OR_NULL_PTR(object))) return;
So, perhaps we should add
data = NULL;
before goto out_err;
?
> + } > + > + /* driver has hw_info callback should have a unique hw_info_type */ > + if (WARN_ON_ONCE(hw_info_type == IOMMU_HW_INFO_TYPE_NONE)) { > + rc = -ENODEV; > + goto out_err; > + } > + > + length = min(cmd->data_len, data_len); > + if (copy_to_user(user_ptr, data, length)) { > + rc = -EFAULT; > + goto out_err; > + } > + > +done: > + /* > + * Zero the trailing bytes if the user buffer is bigger than the > + * data size kernel actually has. > + */ > + if (length < cmd->data_len) { > + rc = iommufd_zero_fill_user(user_ptr + length, > + cmd->data_len - length); > + if (rc) > + goto out_err; > + } > + > + cmd->data_len = length; > + cmd->out_data_type = hw_info_type; > + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd)); > + > +out_err: > + kfree(data); > + iommufd_put_object(&idev->obj); > + return rc; > +} > +
Others look good to me, feel free to add:
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
after above are addressed.
Best regards, baolu
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