Messages in this thread Patch in this message | | | Date | Thu, 9 Mar 2023 21:50:18 +0800 | Subject | Re: [PATCH v2 3/4] iommufd: Add IOMMU_DEVICE_GET_HW_INFO | From | Baolu Lu <> |
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On 2023/3/9 15:53, 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 needs to be compatiable with the underlying IOMMU hardware. Hence, > userspace should know the IOMMU hardware capability before creating and > configuring the stage-1 translation table to kernel. > > This adds IOMMU_DEVICE_GET_HW_INFO to query the IOMMU hardware information > 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/device.c | 74 +++++++++++++++++++++++++ > drivers/iommu/iommufd/iommufd_private.h | 1 + > drivers/iommu/iommufd/main.c | 3 + > include/uapi/linux/iommufd.h | 40 +++++++++++++ > 4 files changed, 118 insertions(+) > > diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c > index c10e02f6a0be..6948539488a5 100644 > --- a/drivers/iommu/iommufd/device.c > +++ b/drivers/iommu/iommufd/device.c > @@ -257,6 +257,80 @@ struct iommufd_ctx *iommufd_device_to_ictx(struct iommufd_device *idev) > } > EXPORT_SYMBOL_NS_GPL(iommufd_device_to_ictx, IOMMUFD); > > +static int iommufd_zero_fill_user(u64 ptr, int bytes) > +{ > + int index = 0; > + > + for (; index < bytes; index++) { > + if (put_user(0, (uint8_t __user *)(ptr + index))) > + return -EFAULT; > + } > + return 0; > +} > + > +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd) > +{ > + struct iommu_hw_info *cmd = ucmd->cmd; > + struct iommufd_device *idev; > + const struct iommu_ops *ops; > + void *data; > + unsigned int length, data_len; > + int rc;
Reverse christmas tree order for declarations.
> + > + 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); > + > + ops = dev_iommu_ops(idev->dev); > + if (!ops || !ops->hw_info) {
dev_iommu_ops() will never return a NULL.
Need below check
dev->iommu && dev->iommu->iommu_dev
before dev_iommu_ops(). Perhaps something like below?
if (!dev->iommu || !dev->iommu->iommu_dev) return -EINVAL;
ops = dev_iommu_ops(idev->dev); if (!ops->hw_info) return -ENODEV;
> + rc = -EOPNOTSUPP; > + goto out_put; > + } > + > + /* driver has hw_info callback should have a unique driver_type */ > + if (WARN_ON(ops->driver_type == IOMMU_HW_INFO_TYPE_DEFAULT)) {
If so, perhaps IOMMU_HW_INFO_TYPE_INVALID is more readable?
I'm not sure if a calltrace is really necessary here. If not, perhaps,
if (ops->driver_type == IOMMU_HW_INFO_TYPE_DEFAULT) { pr_warn_ratelimited("iommu driver set an invalid type\n"); rc = -ENODEV; goto out_put; }
> + rc = -EOPNOTSUPP; > + goto out_put; > + } > + > + data = ops->hw_info(idev->dev, &data_len); > + if (IS_ERR(data)) { > + rc = PTR_ERR(data); > + goto out_put; > + } > + > + length = min(cmd->data_len, data_len); > + if (copy_to_user(u64_to_user_ptr(cmd->data_ptr), data, length)) { > + rc = -EFAULT; > + goto out_free_data; > + } > + > + /* > + * 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(cmd->data_ptr + length, > + cmd->data_len - length); > + if (rc) > + goto out_free_data; > + } > + > + cmd->out_data_type = ops->driver_type; > + cmd->data_len = length; > + > + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd)); > + > +out_free_data: > + kfree(data); > +out_put: > + iommufd_put_object(&idev->obj); > + return rc; > +} > + > static int iommufd_group_setup_msi(struct iommufd_group *igroup, > struct iommufd_hw_pagetable *hwpt) > { > diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h > index b18f843ad6a4..05b5ad66f716 100644 > --- a/drivers/iommu/iommufd/iommufd_private.h > +++ b/drivers/iommu/iommufd/iommufd_private.h > @@ -307,6 +307,7 @@ iommufd_get_device(struct iommufd_ucmd *ucmd, u32 id) > } > > void iommufd_device_destroy(struct iommufd_object *obj); > +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd); > > struct iommufd_access { > struct iommufd_object obj; > diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c > index 694da191e4b1..f079c0bda46b 100644 > --- a/drivers/iommu/iommufd/main.c > +++ b/drivers/iommu/iommufd/main.c > @@ -262,6 +262,7 @@ static int iommufd_option(struct iommufd_ucmd *ucmd) > union ucmd_buffer { > struct iommu_destroy destroy; > struct iommu_hwpt_alloc hwpt; > + struct iommu_hw_info info; > struct iommu_ioas_alloc alloc; > struct iommu_ioas_allow_iovas allow_iovas; > struct iommu_ioas_copy ioas_copy; > @@ -295,6 +296,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = { > IOCTL_OP(IOMMU_DESTROY, iommufd_destroy, struct iommu_destroy, id), > IOCTL_OP(IOMMU_HWPT_ALLOC, iommufd_hwpt_alloc, struct iommu_hwpt_alloc, > __reserved), > + IOCTL_OP(IOMMU_DEVICE_GET_HW_INFO, iommufd_device_get_hw_info, > + struct iommu_hw_info, __reserved), > IOCTL_OP(IOMMU_IOAS_ALLOC, iommufd_ioas_alloc_ioctl, > struct iommu_ioas_alloc, out_ioas_id), > IOCTL_OP(IOMMU_IOAS_ALLOW_IOVAS, iommufd_ioas_allow_iovas, > diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h > index 955cbef640da..4ac525897b82 100644 > --- a/include/uapi/linux/iommufd.h > +++ b/include/uapi/linux/iommufd.h > @@ -46,6 +46,7 @@ enum { > IOMMUFD_CMD_OPTION, > IOMMUFD_CMD_VFIO_IOAS, > IOMMUFD_CMD_HWPT_ALLOC, > + IOMMUFD_CMD_DEVICE_GET_HW_INFO, > }; > > /** > @@ -377,4 +378,43 @@ struct iommu_hwpt_alloc { > enum iommu_hw_info_type { > IOMMU_HW_INFO_TYPE_DEFAULT, > }; > + > +/** > + * struct iommu_hw_info - ioctl(IOMMU_DEVICE_GET_HW_INFO) > + * @size: sizeof(struct iommu_hw_info) > + * @flags: Must be 0 > + * @dev_id: The device being attached to the iommufd > + * @data_len: Input the length of the user buffer in bytes. Output the > + * length of data filled to the user buffer. > + * @data_ptr: Pointer to the type specific structure > + * @out_data_type: Output the iommu hardware info type, it is one of > + * enum iommu_hw_info_type. > + * @__reserved: Must be 0 > + * > + * Query the hardware iommu information for given device which has been > + * bound to iommufd. @data_len is the size of the buffer which captures > + * iommu type specific data and the data will be filled. Trailing bytes > + * are zeroed if the user buffer is larger than the data kernel has. > + * > + * The type specific data would be used to sync capability between the > + * vIOMMU and the hardware IOMMU. e.g. nested translation requires to > + * check the hardware IOMMU capability, since a stage-1 translation table > + * is owned by user but used by hardware IOMMU. > + * > + * The @out_data_type will be filled if the ioctl succeeds. It would > + * be used to decode the data filled in the buffer pointed by @data_ptr. > + * > + * This is only available for the physical devices bound to iommufd as > + * only physical devices can have hardware IOMMU. > + */ > +struct iommu_hw_info { > + __u32 size; > + __u32 flags; > + __u32 dev_id; > + __u32 data_len; > + __aligned_u64 data_ptr; > + __u32 out_data_type; > + __u32 __reserved; > +}; > +#define IOMMU_DEVICE_GET_HW_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_DEVICE_GET_HW_INFO) > #endif
Other look good to me.
Best regards, baolu
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