Based-on: <[email protected]> Support preallocation of memory to make virtio-mem safe to use with scarce memory resources such as hugetlb. Before acknowledging a plug request from the guest, we'll try preallcoating memory. If that fails, we'll fail the request gracefully and warn the usr once.
To fully support huge pages for shared memory, we'll have to adjust shared memory users, such as virtiofsd, to map guest memory via MAP_NORESERVE as well, because otherwise, they'll end up overwriting the "reserve=off" decision made by QEMU and try reserving huge pages for the sparse memory region. In the future, we might want to process guest requests, including preallocating memory, asynchronously via a dedicated iothread. [1] https://lkml.kernel.org/r/[email protected] v1 -> v2: - Rebased - Added RBs Cc: Paolo Bonzini <[email protected]> Cc: "Michael S. Tsirkin" <[email protected]> Cc: Igor Mammedov <[email protected]> Cc: Eduardo Habkost <[email protected]> Cc: Dr. David Alan Gilbert <[email protected]> Cc: Daniel P. Berrangé <[email protected]> Cc: Gavin Shan <[email protected]> Cc: Hui Zhu <[email protected]> Cc: Sebastien Boeuf <[email protected]> Cc: Pankaj Gupta <[email protected]> Cc: Michal Prívozník <[email protected]> David Hildenbrand (8): util/oslib-posix: Let touch_all_pages() return an error util/oslib-posix: Support MADV_POPULATE_WRITE for os_mem_prealloc() util/oslib-posix: Introduce and use MemsetContext for touch_all_pages() util/oslib-posix: Don't create too many threads with small memory or little pages util/oslib-posix: Avoid creating a single thread with MADV_POPULATE_WRITE util/oslib-posix: Support concurrent os_mem_prealloc() invocation util/oslib-posix: Forward SIGBUS to MCE handler under Linux virtio-mem: Support "prealloc=on" option hw/virtio/virtio-mem.c | 39 +++++- include/hw/virtio/virtio-mem.h | 4 + include/qemu/osdep.h | 7 + softmmu/cpus.c | 4 + util/oslib-posix.c | 231 +++++++++++++++++++++++++-------- 5 files changed, 226 insertions(+), 59 deletions(-) -- 2.31.1
