• Greg Edwards's avatar
    KVM: IOMMU: hva align mapping page size · 27ef63c7
    Greg Edwards authored
    When determining the page size we could use to map with the IOMMU, the
    page size should also be aligned with the hva, not just the gfn.  The
    gfn may not reflect the real alignment within the hugetlbfs file.
    
    Most of the time, this works fine.  However, if the hugetlbfs file is
    backed by non-contiguous huge pages, a multi-huge page memslot starts at
    an unaligned offset within the hugetlbfs file, and the gfn is aligned
    with respect to the huge page size, kvm_host_page_size() will return the
    huge page size and we will use that to map with the IOMMU.
    
    When we later unpin that same memslot, the IOMMU returns the unmap size
    as the huge page size, and we happily unpin that many pfns in
    monotonically increasing order, not realizing we are spanning
    non-contiguous huge pages and partially unpin the wrong huge page.
    
    Ensure the IOMMU mapping page size is aligned with the hva corresponding
    to the gfn, which does reflect the alignment within the hugetlbfs file.
    Reviewed-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
    Signed-off-by: default avatarGreg Edwards <gedwards@ddn.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
    27ef63c7
iommu.c 8.25 KB