STRUCT IOMMU_HW_QUEUE_ALLOC(9)

Okay bestie, welcome to struct iommu_hw_queue_alloc(9) in the Kernel API Manual — this is the ioctl(IOMMU_HW_QUEUE_ALLOC) struct and I'm literally obsessed. 💖

💖 NAME 💖

struct iommu_hw_queue_alloc — ioctl(IOMMU_HW_QUEUE_ALLOC) 🫶

✨ SYNOPSIS ✨

Here's the whole struct, no cap:

       struct iommu_hw_queue_alloc {
           __u32 size;
           __u32 flags;
           __u32 viommu_id;
           __u32 type;
           __u32 index;
           __u32 out_hw_queue_id;
           __aligned_u64 nesting_parent_iova;
           __aligned_u64 length;
        };

🧸 Members 🧸

• size — this one is literally sizeof(struct iommu_hw_queue_alloc), so it knows its own size. Main character energy. ✨
• flags — must be 0. No cap, don't get creative here. 💅
• viommu_id — the virtual IOMMU ID to associate the HW queue with.
• type — one of enum iommu_hw_queue_type.
• index — the logical index to the HW queue per virtual IOMMU for a multi-queue model.
• out_hw_queue_id — the ID of the new HW queue.
• nesting_parent_iova — base address of the queue memory in the guest physical address space.
• length — length of the queue memory.

🌸 Description 🌸

So this allocates a HW queue object for a vIOMMU-specific HW-accelerated queue, and it allows HW to access a guest queue memory described using nesting_parent_iova and length. Slay. 🔥

A vIOMMU can allocate multiple queues, but it must use a different index per type to separate each allocation, like:

Type1 HW queue0, Type1 HW queue1, Type2 HW queue0, ...

🦋 SEE ALSO 🦋

Okay bestie, here's the whole friend group of related refs — no skipping, periodt:

• Kernel file ./include/uapi/linux/iommufd.h
• General ioctl format(9)
• struct iommu_destroy(9)
• struct iommu_ioas_alloc(9)
• struct iommu_iova_range(9)
• struct iommu_ioas_iova_ranges(9)
• struct iommu_ioas_allow_iovas(9)
• enum iommufd_ioas_map_flags(9)
• struct iommu_ioas_map(9)
• struct iommu_ioas_noiommu_get_pa(9)
• struct iommu_ioas_map_file(9)
• struct iommu_ioas_copy(9)
• struct iommu_ioas_unmap(9)
• enum iommufd_option(9)
• enum iommufd_option_ops(9)
• struct iommu_option(9)
• enum iommufd_vfio_ioas_op(9)
• struct iommu_vfio_ioas(9)
• enum iommufd_hwpt_alloc_flags(9)
• enum iommu_hwpt_vtd_s1_flags(9)
• struct iommu_hwpt_vtd_s1(9)
• struct iommu_hwpt_arm_smmuv3(9)
• struct iommu_hwpt_amd_guest(9)
• enum iommu_hwpt_data_type(9)
• struct iommu_hwpt_alloc(9)
• enum iommu_hw_info_vtd_flags(9)
• struct iommu_hw_info_vtd(9)
• enum iommu_hw_info_arm_smmuv3_flags(9)
• struct iommu_hw_info_arm_smmuv3(9)
• struct iommu_hw_info_tegra241_cmdqv(9)
• struct iommu_hw_info_amd(9)
• enum iommu_hw_info_type(9)
• enum iommufd_hw_capabilities(9)
• enum iommufd_hw_info_flags(9)
• struct iommu_hw_info(9)
• struct iommu_hwpt_set_dirty_tracking(9)
• enum iommufd_hwpt_get_dirty_bitmap_flags(9)
• struct iommu_hwpt_get_dirty_bitmap(9)
• enum iommu_hwpt_invalidate_data_type(9)
• enum iommu_hwpt_vtd_s1_invalidate_flags(9)
• struct iommu_hwpt_vtd_s1_invalidate(9)
• struct iommu_viommu_arm_smmuv3_invalidate(9)
• struct iommu_hwpt_invalidate(9)
• enum iommu_hwpt_pgfault_flags(9)
• enum iommu_hwpt_pgfault_perm(9)
• struct iommu_hwpt_pgfault(9)
• enum iommufd_page_response_code(9)
• struct iommu_hwpt_page_response(9)
• struct iommu_fault_alloc(9)
• enum iommu_viommu_type(9)
• struct iommu_viommu_tegra241_cmdqv(9)
• struct iommu_viommu_alloc(9)
• struct iommu_vdevice_alloc(9)
• struct iommu_ioas_change_process(9)
• enum iommu_veventq_flag(9)
• struct iommufd_vevent_header(9)
• enum iommu_veventq_type(9)
• struct iommu_vevent_arm_smmuv3(9)
• struct iommu_vevent_tegra241_cmdqv(9)
• struct iommu_veventq_alloc(9)
• enum iommu_hw_queue_type(9)

That’s the whole page, bestie! Source/version: ./include/uapi/linux. Date stamped: October 2026. Page: struct iommu_hw_queue_alloc(9). Mwah 💋