__iommu_copy_struct_to_user(9)

💖 __iommu_copy_struct_to_user — NAME 💖

okay so bestie, this lil function is called __iommu_copy_struct_to_user, and its whole ~vibe~ is: report iommu driver specific user space data 💅✨ It's from the Kernel API Manual (that's the manpage family it lives in, iykyk) and honestly? it's doing the most for backward compatibility. 🫶

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✨ SYNOPSIS ✨

int __iommu_copy_struct_to_user (const struct iommu_user_data *dst_data
, void *src_data , unsigned int data_type , size_t data_len , size_t
min_len );

that's the whole signature, no cap 🧚 like yes it's five whole arguments, we love a thorough queen 👑

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🌸 ARGUMENTS 🌸

okay let's go through them one by one, bestie, don't skip 🎀

• dst_data — Pointer to a struct iommu_user_data for user space data location. it's literally the map to where the user space data lives 🗺️
• src_data — Pointer to an iommu driver specific user data that is defined in include/uapi/linux/iommufd.h. so that's where the actual tea comes from 💖
• data_type — The data type of the src_data. Must match with dst_data.type — like, they HAVE to match, it's giving matching friendship bracelets, no exceptions 🙈
• data_len — Length of current user data structure, i.e. sizeof(struct _src). yes the size, we measure things around here 📏
• min_len — Initial length of user data structure for backward compatibility. This should be offsetofend using the last member in the user data struct that was initially added to include/uapi/linux/iommufd.h. that's the backwards-compat clause, the "we still love our old versions" of it all 🫶✨

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🦋 SEE ALSO 🦋

the reference list is LONG bestie, like a group chat with everyone in it, but every single one is here, mwah 💋

• Kernel file ./include/linux/iommu.h — the source of truth, the mothership 👑
• struct iommu_fault_page_request(9)
• struct iommu_fault(9)
• enum iommu_page_response_code(9)
• struct iommu_page_response(9)
• struct iopf_queue(9)
• struct iommu_resv_region(9)
• struct iommu_iotlb_gather(9)
• struct iommu_dirty_bitmap(9)
• struct iommu_dirty_ops(9)
• struct iommu_user_data(9)
• struct iommu_user_data_array(9)
• __iommu_copy_struct_from_user(9)
• iommu_copy_struct_from_user(9)
• __iommu_copy_struct_from_user_array(9)
• iommu_copy_struct_from_user_array(9)
• iommu_copy_struct_from_full_user_array(9)
• iommu_copy_struct_to_user(9) — that's the non-underscore sibling, hi bestie 👋
• struct iommu_ops(9)
• struct iommu_domain_ops(9)
• struct iommu_device(9)
• struct iommu_fault_param(9)
• struct dev_iommu(9)
• iommu_iotlb_gather_is_disjoint(9)
• iommu_iotlb_gather_add_range(9)
• iommu_iotlb_gather_add_page(9)
• struct iommu_fwspec(9)
• struct iommu_sva(9)
• iommu_map_sgtable(9)

like, that's the whole friend group, and they all ate 🔥

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ngl if you ever forget the exact struct member rules for min_len, just go read include/uapi/linux/iommufd.h — the manpage said so, and I'm just the messenger 💀

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🎀 sign-off 🎀

this iconic lil page came from ./include/linux, dated October 2026, and it's filed under __iommu_copy_struct_to_user(9) — periodt. 💜🌸 go forth and copy those structs to user space, bestie, you've got this 🫶✨