The patchset attempts to implement the virtual NVDIMM for pseries. PAPR semantics is such that each NVDIMM device is comprising of multiple SCM(Storage Class Memory) blocks. The hypervisor is expected to prepare the FDT for the NVDIMM device and send guest a hotplug interrupt with new type RTAS_LOG_V6_HP_TYPE_PMEM currently handled by the upstream kernel. In response to that interrupt, the guest requests the hypervisor to bind each of the SCM blocks of the NVDIMM device using hcalls. There can be SCM block unbind requests in case of driver errors or unplug(not supported now) use cases. The NVDIMM label read/writes are done through hcalls.
Since each virtual NVDIMM device is divided into multiple SCM blocks, the bind, unbind, and queries using hcalls on those blocks can come independently. This doesnt fit well into the qemu device semantics, where the map/unmap are done at the (whole)device/object level granularity. The patchset uses the existing NVDIMM class structures for the implementation. The bind/unbind is left to happen at the device_add/del phase itself instead of at hcalls on-demand. The guest kernel makes bind/unbind requests for the virtual NVDIMM device at the region level granularity. Without interleaving, each virtual NVDIMM device is presented as separate region. There is no way to configure the virtual NVDIMM interleaving for the guests today. So, there is no way a partial bind/unbind request can come for the vNVDIMM in a hcall for a subset of SCM blocks of a virtual NVDIMM. Hence it is safe to do bind/unbind everything during the object_add/del. The free device-memory region which is used for memory hotplug are done using multiple LMBs of size(256MiB) and are expected to be aligned to 256 MiB. As the SCM blocks are mapped to the same region, the SCM blocks also need to be aligned to this size for the subsequent memory hotplug to work. The minimum SCM block size is set to this size for that reason and can be made user configurable in future if required. The first patch moves around the existing static function to common area for using it in the subsequent patches. Second patch adds the FDT entries and basic device support, the third patch adds the hcalls implementation. The patches are also available at https://github.com/ShivaprasadGBhat/qemu.git - pseries-nvdimm-v3 branch and can be used with the upstream kernel. ndctl can be used for configuring the nvdimms inside the guest. This is how it can be used .. Ex : For coldplug, the device to be added in qemu command line as shown below -object memory-backend-file,id=memnvdimm0,prealloc=yes,mem-path=/tmp/nvdimm0,share=yes,size=1073872896 -device nvdimm,label-size=128k,uuid=75a3cdd7-6a2f-4791-8d15-fe0a920e8e9e,memdev=memnvdimm0,id=nvdimm0,slot=0 For hotplug, the device to be added from monitor as below object_add memory-backend-file,id=memnvdimm0,prealloc=yes,mem-path=/tmp/nvdimm0,share=yes,size=1073872896 device_add nvdimm,label-size=128k,uuid=75a3cdd7-6a2f-4791-8d15-fe0a920e8e9e,memdev=memnvdimm0,id=nvdimm0,slot=0 --- v2: https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg02785.html Changes from v2: - Creating the drc indices for the nvdimm devices in advance as suggested based on the number of user specified max slots property. - Removed the hard dependency on -machine nvdimm=on, enabled by default on the current latest pseries machine version. - Renamed the functions to spapr_dt_X as suggested. - Metadata is byteswapped before read/write to take care of endianness semantics during the hcall. v1 : http://lists.nongnu.org/archive/html/qemu-devel/2019-02/msg01545.html Changes from v1: - Rebased to upstream, this required required dt_populate implementation for nvdimm hotplug support - Added uuid option to nvdimm device - Removed the memory region sizing down code as suggested by Igor, now erroring out if NVDIMM size excluding the label area is not aligned to 256MB, so patch 2 from previous series no longer needed. - Removed un-implemented hcalls - Changed the hcalls to different kinds of checks and return different values. - Addressed comments for v1 Shivaprasad G Bhat (3): mem: move nvdimm_device_list to utilities spapr: Add NVDIMM device support spapr: Add Hcalls to support PAPR NVDIMM device default-configs/ppc64-softmmu.mak | 1 hw/acpi/nvdimm.c | 28 --- hw/mem/Kconfig | 2 hw/mem/nvdimm.c | 40 +++++ hw/ppc/spapr.c | 218 +++++++++++++++++++++++++-- hw/ppc/spapr_drc.c | 18 ++ hw/ppc/spapr_events.c | 4 hw/ppc/spapr_hcall.c | 300 +++++++++++++++++++++++++++++++++++++ include/hw/mem/nvdimm.h | 7 + include/hw/ppc/spapr.h | 19 ++ include/hw/ppc/spapr_drc.h | 9 + include/qemu/nvdimm-utils.h | 7 + util/Makefile.objs | 1 util/nvdimm-utils.c | 29 ++++ 14 files changed, 638 insertions(+), 45 deletions(-) create mode 100644 include/qemu/nvdimm-utils.h create mode 100644 util/nvdimm-utils.c -- Signature
