Changelog: since v6: - include and rebase on top of [PATCH 0/2] kvm: clear dirty bitmaps from all overlapping memslots https://www.mail-archive.com/qemu-devel@nongnu.org/msg646200.html - minor fixups suggested during v6 review - more testing incl. hacked x86 since v5: - [1/2] fix migration that wasn't starting and make sure that KVM part is able to handle 1:n MemorySection:memslot arrangement since v3: - fix compilation issue - advance HVA along with GPA in kvm_set_phys_mem() since v2: - break migration from old QEMU (since 2.12-4.1) for guest with >8TB RAM and drop migratable aliases patch as was agreed during v2 review - drop 4.2 machines patch as it's not prerequisite anymore since v1: - include 4.2 machines patch for adding compat RAM layout on top - 2/4 add missing in v1 patch for splitting too big MemorySection on several memslots - 3/4 amend code path on alias destruction to ensure that RAMBlock is cleaned properly - 4/4 add compat machine code to keep old layout (migration-wise) for 4.1 and older machines
While looking into unifying guest RAM allocation to use hostmem backends for initial RAM (especially when -mempath is used) and retiring memory_region_allocate_system_memory() API, leaving only single hostmem backend, I was inspecting how currently it is used by boards and it turns out several boards abuse it by calling the function several times (despite documented contract forbiding it). s390 is one of such boards where KVM limitation on memslot size got propagated to board design and memory_region_allocate_system_memory() was abused to satisfy KVM requirement for max RAM chunk where memory region alias would suffice. Unfortunately, memory_region_allocate_system_memory() usage created migration dependency where guest RAM is transferred in migration stream as several RAMBlocks if it's more than KVM_SLOT_MAX_BYTES. During v2 review it was agreed to ignore migration breakage (documenting it in release notes) and leaving only KVM fix. In order to replace these several RAM chunks with a single memdev and keep it working with KVM memslot size limit, the later was modified to deal with memory section split on several KVMSlots and manual RAM splitting in s390 was replace by single memory_region_allocate_system_memory() call. Tested: * s390 with hacked KVM_SLOT_MAX_BYTES = 128Mb - guest reboot cycle in ping-pong migration * x86 with hacke max memslot = 128 and manual_dirty_log_protect enabled - ping-pong migration with workload dirtying RAM around a split area Igor Mammedov (2): kvm: split too big memory section on several memslots s390: do not call memory_region_allocate_system_memory() multiple times Paolo Bonzini (2): kvm: extract kvm_log_clear_one_slot kvm: clear dirty bitmaps from all overlapping memslots include/sysemu/kvm_int.h | 1 + accel/kvm/kvm-all.c | 238 +++++++++++++++++++++++-------------- hw/s390x/s390-virtio-ccw.c | 30 +---- target/s390x/kvm.c | 11 ++ 4 files changed, 161 insertions(+), 119 deletions(-) -- 2.18.1