vfio_check_precopy_ioctl(9)

💅 vfio_check_precopy_ioctl(9) — like, the Kernel API Manual page you actually wanna read 🎀

okay bestie, so this is a page from the Kernel API Manual (section 9), and it's about one very specific little function that does vibe-check duty on the VFIO_MIG_GET_PRECOPY_INFO ioctl. it's short, it's sweet, and it's lowkey doing important gatekeeping work. let's go ✨

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🌸 NAME 🌸

vfio_check_precopy_ioctl — validates user input for the VFIO_MIG_GET_PRECOPY_INFO ioctl. that's it, that's the whole job. queen of checking ur homework before u submit it 💅

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✨ SYNOPSIS ✨

int vfio_check_precopy_ioctl (struct vfio_device *vdev , unsigned int
cmd , unsigned long arg , struct vfio_precopy_info *info );

literally four params, no cap. signature stays exactly like that, bestie — don't go editing it, i will notice 😭

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🦋 ARGUMENTS 🦋

• vdev — the vfio device. the whole main character of the situation, honestly 👑
• cmd — the cmd that came in from the ioctl. yes, it got passed along, it's doing its little cameo 🎬
• arg — the arg from the ioctl. same deal, straight from userspace to here 🫶
• info — a driver pointer that holds the userspace input to the ioctl. think of it as the lil basket where the driver keeps what userspace handed over 🧺

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🔥 DESCRIPTION 🔥

so this function is meant to be used inside a driver's get_precopy_info. what it does is check that the inputs to the VFIO_MIG_GET_PRECOPY_INFO ioctl are, y'know, correct — like a bouncer at the club but for ioctl arguments 🚪✨

returns 0 on success, otherwise it hands you back an errno. simple as that. no drama, no extra lore 💀

ngl, "otherwise errno" is doing a lot of heavy lifting here — that's the whole error contract, bestie. don't go inventing extra behaviour, the page doesn't say it and neither will i 🙈

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🌈 SEE ALSO 🌈

• Kernel file ./include/linux/vfio.h
• struct vfio_device_ops(9)
• struct vfio_migration_ops(9)
• struct vfio_log_ops(9)
• vfio_check_feature(9)

all the related lore, iykyk 🧚💜

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aaaand that's the page, bestie 🫶 the source path for this one is ./include/linux and it's dated October 2026 — so yeah, mark ur calendar, iconic behavior from the future 🔥👑 slay, periodt, go check those ioctl inputs 💖