On Thu, May 01, 2025 at 10:29:58PM -0700, Nicolin Chen wrote: > On Fri, May 02, 2025 at 10:50:07AM +0700, Bagas Sanjaya wrote: > > On Thu, May 01, 2025 at 04:01:22PM -0700, Nicolin Chen wrote: > > > +- IOMMUFD_OBJ_VQUEUE, representing a hardware accelerated virtual queue, > > > as a > > > + subset of IOMMU's virtualization features, for the IOMMU HW to > > > directly read > > > + or write the virtual queue memory owned by a guest OS. This > > > HW-acceleration > > > + allows VM to work with the IOMMU HW directly without a VM Exit, i.e. > > > reducing > > > + overhead from the hypercalls. Along with this vQUEUE object, iommufd > > > provides > > > + user space an mmap interface for VMM to mmap a physical MMIO region > > > from the > > > + host physical address space to the guest physical address space, > > > allowing the > > > + guest OS to control the allocated vQUEUE HW. Thus, when allocating a > > > vQUEUE, > > > + the VMM must request a pair of VMA info (vm_pgoff/size) for an mmap > > > syscall. > > > + The length argument of an mmap syscall can be smaller than the given > > > size for > > > + a partial mmap, but the addr argument of the mmap syscall should never > > > offset > > > + from the returned vm_pgoff, which implies that an mmap will always > > > start from > > > > Did you mean never be offset from returned vm_pgoff? > > Yes. Will fix this. > > > > + the beginning of the physical MMIO region. > > > + > > > > Confused... > > Meaning that VMM should just use the given vm_pgoff as is, without > adding any offset to the vm_pgoff.
Understood, thanks! -- An old man doll... just what I always wanted! - Clara
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