>-----Original Message----- >From: Liu, Yi L <[email protected]> >Subject: Re: [PATCH v2 6/8] intel_iommu: Fix unmap_bitmap failure with >legacy VFIO backend > >On 2025/10/17 16:22, Zhenzhong Duan wrote: >> If a VFIO device in guest switches from IOMMU domain to block domain, >> vtd_address_space_unmap() is called to unmap whole address space. >> >> If that happens during migration, migration fails with legacy VFIO >> backend as below: >> >> Status: failed (vfio_container_dma_unmap(0x561bbbd92d90, >0x100000000000, 0x100000000000) = -7 (Argument list too long)) >> >> Because legacy VFIO limits maximum bitmap size to 256MB which maps to >8TB on >> 4K page system, when 16TB sized UNMAP notification is sent, >unmap_bitmap >> ioctl fails. > >It would be great to add some words to note why vIOMMU can trigger this.
Hi Yi, I think the first sentence in description is explaining that? "If a VFIO device in guest switches from IOMMU domain to block domain, vtd_address_space_unmap() is called to unmap whole address space." Thanks Zhenzhong
