Changelog: 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, following was done: * [1/2] split too big RAM chunk inside of KVM code on several memory slots if necessary * [2/2] drop manual ram splitting in s390 code CC: pbonz...@redhat.com CC: qemu-s3...@nongnu.org CC: borntrae...@de.ibm.com CC: th...@redhat.com CC: da...@redhat.com CC: coh...@redhat.com Igor Mammedov (2): kvm: s390: split too big memory section on several memslots s390: do not call memory_region_allocate_system_memory() multiple times include/hw/s390x/s390-virtio-ccw.h | 10 ++++ include/sysemu/kvm_int.h | 1 + accel/kvm/kvm-all.c | 79 ++++++++++++++++++------------ hw/s390x/s390-virtio-ccw.c | 30 ++---------- target/s390x/kvm.c | 1 + 5 files changed, 63 insertions(+), 58 deletions(-) -- 2.18.1