Re: [PATCH v2 15/22] Documentation: userspace-api: iommufd: Update vCMDQ

Bagas Sanjaya
2025-04-28T14:35:20Z

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On Fri, Apr 25, 2025 at 10:58:10PM -0700, Nicolin Chen wrote:
> +- IOMMUFD_OBJ_VCMDQ, representing a hardware queue as a subset of a vIOMMU's
> + virtualization feature for a VM to directly execute guest-issued commands to
> + invalidate HW cache entries holding the mappings or translations of a guest-
> + owned stage-1 page table. Along with this queue object, iommufd provides the
> + user space an mmap interface for VMM to mmap a physical MMIO region from the
> + host physical address space to a guest physical address space, to exclusively
> + control the allocated vCMDQ HW. Thus, when allocating a vCMDQ, the VMM must
> + request a pair of VMA info (vm_pgoff/size) for a later mmap call. The length
> + argument of an mmap call could be smaller than the given size for a paritial
> + mmap, but the given vm_pgoff (as the addr argument of the mmap call) should
"... partial mmap, ..."
> + never be offsetted, which also implies that the mmap will always start from
> + the beginning of the physical MMIO region.
> +

Thanks.

--
An old man doll... just what I always wanted! - Clara

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