iommu_dma_prepare_msi(9)

✨ iommu_dma_prepare_msi ✨

okay so bestie, welcome to the Kernel API Manual 💖 this one's a little function with a big job: getting your MSI page actually mapped into the IOMMU domain. no cap, it's short, but it matters. let's get into it 🎀

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🌸 SYNOPSIS 🌸

int iommu_dma_prepare_msi (struct msi_desc *desc , phys_addr_t msi_addr );

like, two params, one int coming back at you. that's the whole vibe check 💅

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🦋 ARGUMENTS 🦋

• desc — the MSI descriptor, and heads up: this is where the MSI page gets stored. so it's not just a read, it's literally the storage spot, main character energy fr 🫶
• msi_addr — the MSI target address that's gonna be mapped. that's the thing we're putting on the map 🗺️✨

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💜 DESCRIPTION 💜

so the implementation of sw_msi should take msi_addr, map it to an IOVA in the domain, and then call msi_desc_set_iommu_msi_iova with the mapping information. that's it. that's the whole assignment 😌

think of it as: grab the address → give it a home in the domain → tell everyone where it lives via msi_desc_set_iommu_msi_iova 💫 not me explaining IOMMU at 2am lmaooo but it's giving very clear instructions ngl.

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⭐ RETURN ⭐

0 on success 🎉 — or a negative error code if the mapping failed 😭 (yes, negative. it's a "something went wrong" situation, lowkey sad but that's how we report it).

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🌈 SEE ALSO 🌈

okay bestie this list is iconic and honestly kind of long, so buckle up 🎢 — kernel file ./drivers/iommu/iommu.c and all of these:

• iommu_device_register(9)
• iommu_insert_resv_region(9)
• iommu_group_alloc(9)
• iommu_group_get_iommudata(9)
• iommu_group_set_iommudata(9)
• iommu_group_set_name(9)
• iommu_group_add_device(9)
• iommu_group_remove_device(9)
• iommu_group_mutex_assert(9)
• iommu_group_for_each_dev(9)
• iommu_group_get(9)
• iommu_group_ref_get(9)
• iommu_group_put(9)
• iommu_group_id(9)
• device_iommu_capable(9)
• iommu_group_has_isolated_msi(9)
• iommu_set_fault_handler(9)
• iommu_paging_domain_alloc_flags(9)
• iommu_attach_device(9)
• iommu_get_domain_for_dev(9)
• iommu_driver_get_domain_for_dev(9)
• iommu_attach_group(9)
• iommu_unmap(9)
• iommu_unmap_fast(9)
• report_iommu_fault(9)
• iommu_get_resv_regions(9)
• iommu_put_resv_regions(9)
• iommu_setup_default_domain(9)
• iommu_device_use_default_domain(9)
• iommu_device_unuse_default_domain(9)
• iommu_group_claim_dma_owner(9)
• iommu_device_claim_dma_owner(9)
• iommu_group_release_dma_owner(9)
• iommu_device_release_dma_owner(9)
• iommu_group_dma_owner_claimed(9)
• iommu_replace_device_pasid(9)
• iommu_attach_handle_get(9)
• iommu_attach_group_handle(9)
• iommu_detach_group_handle(9)
• iommu_replace_group_handle(9)
• pci_dev_reset_iommu_prepare(9)
• pci_dev_reset_iommu_done(9)

like I said. a whole squad 🫶

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and that's the page, bestie!! ily, go map something 🧚💜

sign-off szn 🌸: this lil beauty lives in ./drivers/iommu, dated October 2026, and it's brought to you by the iommu_dma_prepare_msi(9) girlies 💅 periodt.