iopt_map_user_pages(9)

💅 iopt_map_user_pages — bestie's guide to the kernel API manual ✨

okay so real talk, this page lives in the Kernel API Manual and it's literally about iopt_map_user_pages, which maps a user VA to an iova in the io page table. no cap, that's the whole vibe. let's get into it 🫶

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✨ NAME ✨

iopt_map_user_pages — Map a user VA to an iova in the io page table

like... that's the entire job description and she ate 💅

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🌸 SYNOPSIS 🌸

int iopt_map_user_pages (struct iommufd_ctx *ictx , struct io_pagetable
*iopt , unsigned long *iova , void __user *uptr , unsigned long length ,
int iommu_prot , unsigned int flags );

fr fr that's the signature, copy it exactly, don't be weird about it 😭

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🎀 ARGUMENTS 🎀

• ictx — the iommufd_ctx that the iopt is part of. she's the context, she belongs to somebody 💖
• iopt — the io_pagetable we're acting on. this is the main character of the operation 👑
• iova — okay so this one's spicy 🌶️: if IOPT_ALLOC_IOVA is set, this is unused on input and on output it holds the chosen iova. otherwise, on input, it's the iova you're mapping to. iykyk.
• uptr — the user VA you're mapping. literally the thing 🦋
• length — number of bytes to map. count 'em 📏
• iommu_prot — a combination of IOMMU_READ/WRITE/etc bits for the mapping. mix and match, slay ✨
• flags — either IOPT_ALLOC_IOVA or zero. that's it, those are the options, periodt 💀

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🧚 DESCRIPTION 🧚

okay so listen 👂: iova, uptr, and length must be aligned to iova_alignment. not optional, not a suggestion, it's giving requirements 🔥

so for domain backed page tables, this will pin the pages and load them into the domain at iova. very hands-on, very involved 💅

but for non-domain page tables? highkey different energy — this will only set up a lazy reference, and the caller must use iopt_access_pages to touch them. lowkey the work is deferred, ngl 🙈

⚠️ warning bestie: iopt_unmap_iova must be called to undo this before the io_pagetable can be destroyed. do not skip this step, I am begging 😭

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💜 SEE ALSO 💜

• Kernel file ./drivers/iommu/iommufd/io_pagetable.c — go read the source, it's right there 🍓
• iopt_map_file_pages(9)
• iopt_unmap_iova(9)
• iopt_unfill_domain(9)
• iopt_fill_domain(9)
• iopt_area_split(9)

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and that's the page!! 🌈 this one came from ./drivers/iommu/iommufd and it's dated October 2026 — so like, future girlie energy fr fr ⭐ mwah, go map some pages responsibly 💖🎀