The current implementation of KVM guest-memfd does not honor the settings provided by VMM. While mbind() can be used for NUMA policy support in userspace applications, it is not functional for guest-memfd as the memory is not mapped to userspace. This patch-series adds support to specify NUMA memory policy for guests with private guest-memfd memory backend. KVM guest-memfd support for memory backend is already available in QEMU RAMBlock. However, the NUMA support was missing. This cause memory allocation from guest to randomly allocate on host NUMA nodes even when passing policy and host-nodes in the QEMU command. It ensures that VMM provided NUMA policy is adhered. This feature is particularly useful for SEV-SNP guests as they require guest_memfd memory backend for allocations. Workloads with high memory- locality are likely to benefit with this change. Users can provide a policy mode such as default, bind, interleave, or preferred along with a list of node IDs from the host machine. To try this patch-series, build the custom QEMU with NUMA supported KVM guest-memfd: QEMU tree- https://github.com/AMDESE/qemu/tree/NUMA_guest_memfd For instance, to run a SEV-SNP guest bound to NUMA Node 0 of the host, the corresponding QEMU command would be: $ qemu-system-x86_64 \ -enable-kvm \ ... -machine memory-encryption=sev0,vmport=off \ -object sev-snp-guest,id=sev0,cbitpos=51,reduced-phys-bits=1 \ -numa node,nodeid=0,memdev=ram0,cpus=0-15 \ -object memory-backend-memfd,id=ram0,policy=bind,host-nodes=0,size=1024M,share=true,prealloc=false v2: - Add fixes suggested by Matthew Wilcox v1: https://lore.kernel.org/linux-mm/20240916165743.201087-1-shivankg@xxxxxxx Shivansh Dhiman (3): KVM: guest_memfd: Extend creation API to support NUMA mempolicy mm: Add mempolicy support to the filemap layer KVM: guest_memfd: Enforce NUMA mempolicy if available Documentation/virt/kvm/api.rst | 13 ++++++++- include/linux/mempolicy.h | 4 +++ include/linux/pagemap.h | 40 ++++++++++++++++++++++++++ include/uapi/linux/kvm.h | 5 +++- mm/filemap.c | 30 ++++++++++++++++---- mm/mempolicy.c | 52 ++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/kvm.h | 5 +++- virt/kvm/guest_memfd.c | 28 ++++++++++++++---- virt/kvm/kvm_mm.h | 3 ++ 9 files changed, 167 insertions(+), 13 deletions(-) -- 2.34.1
