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iommufd: Add IOMMU_GET_HW_INFO
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 compatible 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_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 by the output @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. Link: https://lore.kernel.org/r/20230818101033.4100-4-yi.l.liu@intel.com Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> 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> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
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4 changed files with 116 additions and 0 deletions
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@ -4,6 +4,7 @@
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#include <linux/iommufd.h>
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#include <linux/slab.h>
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#include <linux/iommu.h>
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#include <uapi/linux/iommufd.h>
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#include "../iommu-priv.h"
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#include "io_pagetable.h"
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@ -1119,3 +1120,75 @@ int iommufd_access_rw(struct iommufd_access *access, unsigned long iova,
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return rc;
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}
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EXPORT_SYMBOL_NS_GPL(iommufd_access_rw, IOMMUFD);
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int iommufd_get_hw_info(struct iommufd_ucmd *ucmd)
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{
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struct iommu_hw_info *cmd = ucmd->cmd;
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void __user *user_ptr = u64_to_user_ptr(cmd->data_uptr);
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const struct iommu_ops *ops;
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struct iommufd_device *idev;
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unsigned int data_len;
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unsigned int copy_len;
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void *data;
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int rc;
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if (cmd->flags || cmd->__reserved)
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return -EOPNOTSUPP;
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idev = iommufd_get_device(ucmd, cmd->dev_id);
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if (IS_ERR(idev))
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return PTR_ERR(idev);
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ops = dev_iommu_ops(idev->dev);
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if (ops->hw_info) {
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data = ops->hw_info(idev->dev, &data_len, &cmd->out_data_type);
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if (IS_ERR(data)) {
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rc = PTR_ERR(data);
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goto out_put;
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}
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/*
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* drivers that have hw_info callback should have a unique
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* iommu_hw_info_type.
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*/
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if (WARN_ON_ONCE(cmd->out_data_type ==
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IOMMU_HW_INFO_TYPE_NONE)) {
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rc = -ENODEV;
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goto out_free;
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}
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} else {
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cmd->out_data_type = IOMMU_HW_INFO_TYPE_NONE;
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data_len = 0;
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data = NULL;
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}
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copy_len = min(cmd->data_len, data_len);
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if (copy_to_user(user_ptr, data, copy_len)) {
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rc = -EFAULT;
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goto out_free;
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}
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/*
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* Zero the trailing bytes if the user buffer is bigger than the
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* data size kernel actually has.
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*/
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if (copy_len < cmd->data_len) {
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if (clear_user(user_ptr + copy_len, cmd->data_len - copy_len)) {
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rc = -EFAULT;
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goto out_free;
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}
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}
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/*
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* We return the length the kernel supports so userspace may know what
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* the kernel capability is. It could be larger than the input buffer.
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*/
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cmd->data_len = data_len;
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rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
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out_free:
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kfree(data);
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out_put:
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iommufd_put_object(&idev->obj);
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return rc;
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}
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@ -296,6 +296,7 @@ iommufd_get_device(struct iommufd_ucmd *ucmd, u32 id)
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}
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void iommufd_device_destroy(struct iommufd_object *obj);
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int iommufd_get_hw_info(struct iommufd_ucmd *ucmd);
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struct iommufd_access {
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struct iommufd_object obj;
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@ -305,6 +305,7 @@ static int iommufd_option(struct iommufd_ucmd *ucmd)
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union ucmd_buffer {
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struct iommu_destroy destroy;
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struct iommu_hw_info info;
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struct iommu_hwpt_alloc hwpt;
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struct iommu_ioas_alloc alloc;
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struct iommu_ioas_allow_iovas allow_iovas;
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@ -337,6 +338,8 @@ struct iommufd_ioctl_op {
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}
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static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
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IOCTL_OP(IOMMU_DESTROY, iommufd_destroy, struct iommu_destroy, id),
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IOCTL_OP(IOMMU_GET_HW_INFO, iommufd_get_hw_info, struct iommu_hw_info,
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__reserved),
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IOCTL_OP(IOMMU_HWPT_ALLOC, iommufd_hwpt_alloc, struct iommu_hwpt_alloc,
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__reserved),
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IOCTL_OP(IOMMU_IOAS_ALLOC, iommufd_ioas_alloc_ioctl,
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@ -46,6 +46,7 @@ enum {
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IOMMUFD_CMD_OPTION,
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IOMMUFD_CMD_VFIO_IOAS,
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IOMMUFD_CMD_HWPT_ALLOC,
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IOMMUFD_CMD_GET_HW_INFO,
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};
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/**
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@ -379,4 +380,42 @@ struct iommu_hwpt_alloc {
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enum iommu_hw_info_type {
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IOMMU_HW_INFO_TYPE_NONE,
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};
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/**
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* struct iommu_hw_info - ioctl(IOMMU_GET_HW_INFO)
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* @size: sizeof(struct iommu_hw_info)
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* @flags: Must be 0
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* @dev_id: The device bound to the iommufd
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* @data_len: Input the length of a user buffer in bytes. Output the length of
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* data that kernel supports
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* @data_uptr: User pointer to a user-space buffer used by the kernel to fill
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* the iommu type specific hardware information data
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* @out_data_type: Output the iommu hardware info type as defined in the enum
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* iommu_hw_info_type.
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* @__reserved: Must be 0
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*
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* Query an iommu type specific hardware information data from an iommu behind
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* a given device that has been bound to iommufd. This hardware info data will
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* be used to sync capabilities between the virtual iommu and the physical
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* iommu, e.g. a nested translation setup needs to check the hardware info, so
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* a guest stage-1 page table can be compatible with the physical iommu.
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*
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* To capture an iommu type specific hardware information data, @data_uptr and
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* its length @data_len must be provided. Trailing bytes will be zeroed if the
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* user buffer is larger than the data that kernel has. Otherwise, kernel only
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* fills the buffer using the given length in @data_len. If the ioctl succeeds,
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* @data_len will be updated to the length that kernel actually supports,
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* @out_data_type will be filled to decode the data filled in the buffer
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* pointed by @data_uptr. Input @data_len == zero is allowed.
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*/
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struct iommu_hw_info {
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__u32 size;
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__u32 flags;
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__u32 dev_id;
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__u32 data_len;
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__aligned_u64 data_uptr;
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__u32 out_data_type;
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__u32 __reserved;
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};
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#define IOMMU_GET_HW_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_GET_HW_INFO)
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#endif
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