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23a980cd54
On aarch64 with 64K host pages, VFIO passthrough of devices with sub-page BARs (e.g. 16K NVMe BAR0) crashes with EINVAL from KVM_SET_USER_MEMORY_REGION, which requires memory_size to be a multiple of the host page size. Expand the mmap to page size instead of rejecting it, matching QEMU's approach. The kernel's vfio_pci_probe_mmaps() already verifies that sub-page BARs are page-aligned and reserves the remainder of the page, so expansion is safe at offset 0. Reject sub-page sparse areas at non-zero offsets where this guarantee does not apply. The expanded mmap region will not overlap with the relocated MSI-X trap region because fixup_msix_region() ensures MSI-X relocation at >= page_size offset. Signed-off-by: Saravanan D <saravanand@crusoe.ai>