Let's try to detect the actual THP size and use it as default block size (unless the page size of the backend indicates that THP don't apply). Always allow to set a block size of 1 MiB, but warn if the configured block size is smaller than the default. Handle large block sizes better, avoiding a virtio-spec violation and optimizing address auto-detection.
For existing setups (x86-64), the default block size won't change (was, and will be 2 MiB on anonymous memory). For existing x86-64 setups, the address auto-detection won't change in relevant setups (esp., anonymous memory and hugetlbfs with 2 MiB pages and no manual configuration of the block size). I don't see the need for compatibility handling (especially, as virtio-mem is still not considered production-ready). Most of this is a preparation for future architectures, using hugetlbfs to full extend, and using manually configured, larger block sizes (relevant for vfio in the future). v1 -> v2: - Tweak some patch descriptions - "virtio-mem: Probe THP size to determine default block size" -- Beautify THP detection a bit. -- Assume THP might only get used if the memory backend page size corresponds to the real hostpage size. -- Use virtio_mem_default_block_size(RAMBlock *rb) to handle selection of the default block size for a RAMBlock. -- Implement virtio_mem_get_block_size() as preparation for patch #5 - "memory-device: Add get_min_alignment() callback" -- Simplify documentation. - "virito-mem: Implement get_min_alignment()" -- Simplify due to changes in patch #1. David Hildenbrand (5): virtio-mem: Probe THP size to determine default block size virtio-mem: Check that "memaddr" is multiples of the block size memory-device: Support big alignment requirements memory-device: Add get_min_alignment() callback virito-mem: Implement get_min_alignment() hw/mem/memory-device.c | 20 ++++-- hw/virtio/virtio-mem-pci.c | 7 +++ hw/virtio/virtio-mem.c | 110 +++++++++++++++++++++++++++++++-- include/hw/mem/memory-device.h | 10 +++ 4 files changed, 137 insertions(+), 10 deletions(-) -- 2.26.2
