Re: [Qemu-devel] [PATCH v3 00/32] implement vNVDIMM

[Bharata B Rao]

Xiao,

Are these patches present in any git tree so that they can be easily tried out.

Regards,
Bharata.

On Sun, Oct 11, 2015 at 9:22 AM, Xiao Guangrong
<address@hidden> wrote:
> Changelog in v3:
> There is huge change in this version, thank Igor, Stefan, Paolo, Eduardo,
> Michael for their valuable comments, the patchset finally gets better shape.
> - changes from Igor's comments:
>   1) abstract dimm device type from pc-dimm and create nvdimm device based on
>      dimm, then it uses memory backend device as nvdimm's memory and NUMA has
>      easily been implemented.
>   2) let file-backend device support any kind of filesystem not only for
>      hugetlbfs and let it work on file not only for directory which is
>      achieved by extending 'mem-path' - if it's a directory then it works as
>      current behavior, otherwise if it's file then directly allocates memory
>      from it.
>   3) we figure out a unused memory hole below 4G that is 0xFF00000 ~
>      0xFFF00000, this range is large enough for NVDIMM ACPI as build 64-bit
>      ACPI SSDT/DSDT table will break windows XP.
>      BTW, only make SSDT.rev = 2 can not work since the width is only depended
>      on DSDT.rev based on 19.6.28 DefinitionBlock (Declare Definition Block)
>      in ACPI spec:
> | Note: For compatibility with ACPI versions before ACPI 2.0, the bit
> | width of Integer objects is dependent on the ComplianceRevision of the DSDT.
> | If the ComplianceRevision is less than 2, all integers are restricted to 32
> | bits. Otherwise, full 64-bit integers are used. The version of the DSDT sets
> | the global integer width for all integers, including integers in SSDTs.
>   4) use the lowest ACPI spec version to document AML terms.
>   5) use "nvdimm" as nvdimm device name instead of "pc-nvdimm"
>
> - changes from Stefan's comments:
>   1) do not do endian adjustment in-place since _DSM memory is visible to 
> guest
>   2) use target platform's target page size instead of fixed PAGE_SIZE
>      definition
>   3) lots of code style improvement and typo fixes.
>   4) live migration fix
> - changes from Paolo's comments:
>   1) improve the name of memory region
>
> - other changes:
>   1) return exact buffer size for _DSM method instead of the page size.
>   2) introduce mutex in NVDIMM ACPI as the _DSM memory is shared by all nvdimm
>      devices.
>   3) NUMA support
>   4) implement _FIT method
>   5) rename "configdata" to "reserve-label-data"
>   6) simplify _DSM arg3 determination
>   7) main changelog update to let it reflect v3.
>
> Changlog in v2:
> - Use litten endian for DSM method, thanks for Stefan's suggestion
>
> - introduce a new parameter, @configdata, if it's false, Qemu will
>   build a static and readonly namespace in memory and use it serveing
>   for DSM GET_CONFIG_SIZE/GET_CONFIG_DATA requests. In this case, no
>   reserved region is needed at the end of the @file, it is good for
>   the user who want to pass whole nvdimm device and make its data
>   completely be visible to guest
>
> - divide the source code into separated files and add maintain info
>
> BTW, PCOMMIT virtualization on KVM side is work in progress, hopefully will
> be posted on next week
>
> ====== Background ======
> NVDIMM (A Non-Volatile Dual In-line Memory Module) is going to be supported
> on Intel's platform. They are discovered via ACPI and configured by _DSM
> method of NVDIMM device in ACPI. There has some supporting documents which
> can be found at:
> ACPI 6: http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf
> NVDIMM Namespace: http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf
> DSM Interface Example: 
> http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf
> Driver Writer's Guide: 
> http://pmem.io/documents/NVDIMM_Driver_Writers_Guide.pdf
>
> Currently, the NVDIMM driver has been merged into upstream Linux Kernel and
> this patchset tries to enable it in virtualization field
>
> ====== Design ======
> NVDIMM supports two mode accesses, one is PMEM which maps NVDIMM into CPU's
> address space then CPU can directly access it as normal memory, another is
> BLK which is used as block device to reduce the occupying of CPU address
> space
>
> BLK mode accesses NVDIMM via Command Register window and Data Register window.
> BLK virtualization has high workload since each sector access will cause at
> least two VM-EXIT. So we currently only imperilment vPMEM in this patchset
>
> --- vPMEM design ---
> We introduce a new device named "nvdimm", it uses memory backend device as
> NVDIMM memory. The file in file-backend device can be a regular file and block
> device. We can use any file when we do test or emulation, however,
> in the real word, the files passed to guest are:
> - the regular file in the filesystem with DAX enabled created on NVDIMM device
>   on host
> - the raw PMEM device on host, e,g /dev/pmem0
> Memory access on the address created by mmap on these kinds of files can
> directly reach NVDIMM device on host.
>
> --- vConfigure data area design ---
> Each NVDIMM device has a configure data area which is used to store label
> namespace data. In order to emulating this area, we divide the file into two
> parts:
> - first parts is (0, size - 128K], which is used as PMEM
> - 128K at the end of the file, which is used as Label Data Area
> So that the label namespace data can be persistent during power lose or system
> failure.
>
> We also support passing the whole file to guest without reserve any region for
> label data area which is achieved by "reserve-label-data" parameter - if it's
> false then QEMU will build static and readonly namespace in memory and that
> namespace contains the whole file size. The parameter is false on default.
>
> --- _DSM method design ---
> _DSM in ACPI is used to configure NVDIMM, currently we only allow access of
> label namespace data, i.e, Get Namespace Label Size (Function Index 4),
> Get Namespace Label Data (Function Index 5) and Set Namespace Label Data
> (Function Index 6)
>
> _DSM uses two pages to transfer data between ACPI and Qemu, the first page
> is RAM-based used to save the input info of _DSM method and Qemu reuse it
> store output info and another page is MMIO-based, ACPI write data to this
> page to transfer the control to Qemu
>
> ====== Test ======
> In host
> 1) create memory backed file, e.g # dd if=zero of=/tmp/nvdimm bs=1G count=10
> 2) append "-object memory-backend-file,share,id=mem1,
>    mem-path=/tmp/nvdimm -device nvdimm,memdev=mem1,reserve-label-data,
>    id=nv1" in QEMU command line
>
> In guest, download the latest upsteam kernel (4.2 merge window) and enable
> ACPI_NFIT, LIBNVDIMM and BLK_DEV_PMEM.
> 1) insmod drivers/nvdimm/libnvdimm.ko
> 2) insmod drivers/acpi/nfit.ko
> 3) insmod drivers/nvdimm/nd_btt.ko
> 4) insmod drivers/nvdimm/nd_pmem.ko
> You can see the whole nvdimm device used as a single namespace and /dev/pmem0
> appears. You can do whatever on /dev/pmem0 including DAX access.
>
> Currently Linux NVDIMM driver does not support namespace operation on this
> kind of PMEM, apply below changes to support dynamical namespace:
>
> @@ -798,7 +823,8 @@ static int acpi_nfit_register_dimms(struct acpi_nfit_desc 
> *a
>                         continue;
>                 }
>
> -               if (nfit_mem->bdw && nfit_mem->memdev_pmem)
> +               //if (nfit_mem->bdw && nfit_mem->memdev_pmem)
> +               if (nfit_mem->memdev_pmem)
>                         flags |= NDD_ALIASING;
>
> You can append another NVDIMM device in guest and do:
> # cd /sys/bus/nd/devices/
> # cd namespace1.0/
> # echo `uuidgen` > uuid
> # echo `expr 1024 \* 1024 \* 128` > size
> then reload nd.pmem.ko
>
> You can see /dev/pmem1 appears
>
> ====== TODO ======
> NVDIMM hotplug support
>
> Xiao Guangrong (32):
>   acpi: add aml_derefof
>   acpi: add aml_sizeof
>   acpi: add aml_create_field
>   acpi: add aml_mutex, aml_acquire, aml_release
>   acpi: add aml_concatenate
>   acpi: add aml_object_type
>   util: introduce qemu_file_get_page_size()
>   exec: allow memory to be allocated from any kind of path
>   exec: allow file_ram_alloc to work on file
>   hostmem-file: clean up memory allocation
>   hostmem-file: use whole file size if possible
>   pc-dimm: remove DEFAULT_PC_DIMMSIZE
>   pc-dimm: make pc_existing_dimms_capacity static and rename it
>   pc-dimm: drop the prefix of pc-dimm
>   stubs: rename qmp_pc_dimm_device_list.c
>   pc-dimm: rename pc-dimm.c and pc-dimm.h
>   dimm: abstract dimm device from pc-dimm
>   dimm: get mapped memory region from DIMMDeviceClass->get_memory_region
>   dimm: keep the state of the whole backend memory
>   dimm: introduce realize callback
>   nvdimm: implement NVDIMM device abstract
>   nvdimm: init the address region used by NVDIMM ACPI
>   nvdimm: build ACPI NFIT table
>   nvdimm: init the address region used by DSM method
>   nvdimm: build ACPI nvdimm devices
>   nvdimm: save arg3 for NVDIMM device _DSM method
>   nvdimm: support DSM_CMD_IMPLEMENTED function
>   nvdimm: support DSM_CMD_NAMESPACE_LABEL_SIZE function
>   nvdimm: support DSM_CMD_GET_NAMESPACE_LABEL_DATA
>   nvdimm: support DSM_CMD_SET_NAMESPACE_LABEL_DATA
>   nvdimm: allow using whole backend memory as pmem
>   nvdimm: add maintain info
>
>  MAINTAINERS                                        |   6 +
>  backends/hostmem-file.c                            |  58 +-
>  default-configs/i386-softmmu.mak                   |   2 +
>  default-configs/x86_64-softmmu.mak                 |   2 +
>  exec.c                                             | 113 ++-
>  hmp.c                                              |   2 +-
>  hw/Makefile.objs                                   |   2 +-
>  hw/acpi/aml-build.c                                |  83 ++
>  hw/acpi/ich9.c                                     |   8 +-
>  hw/acpi/memory_hotplug.c                           |  26 +-
>  hw/acpi/piix4.c                                    |   8 +-
>  hw/i386/acpi-build.c                               |   4 +
>  hw/i386/pc.c                                       |  37 +-
>  hw/mem/Makefile.objs                               |   3 +
>  hw/mem/{pc-dimm.c => dimm.c}                       | 240 ++---
>  hw/mem/nvdimm/acpi.c                               | 961 
> +++++++++++++++++++++
>  hw/mem/nvdimm/internal.h                           |  41 +
>  hw/mem/nvdimm/namespace.c                          | 309 +++++++
>  hw/mem/nvdimm/nvdimm.c                             | 136 +++
>  hw/mem/pc-dimm.c                                   | 506 +----------
>  hw/ppc/spapr.c                                     |  20 +-
>  include/hw/acpi/aml-build.h                        |   8 +
>  include/hw/i386/pc.h                               |   4 +-
>  include/hw/mem/{pc-dimm.h => dimm.h}               |  68 +-
>  include/hw/mem/nvdimm.h                            |  58 ++
>  include/hw/mem/pc-dimm.h                           | 105 +--
>  include/hw/ppc/spapr.h                             |   2 +-
>  include/qemu/osdep.h                               |   1 +
>  numa.c                                             |   4 +-
>  qapi-schema.json                                   |   8 +-
>  qmp.c                                              |   4 +-
>  stubs/Makefile.objs                                |   2 +-
>  ...c_dimm_device_list.c => qmp_dimm_device_list.c} |   4 +-
>  target-ppc/kvm.c                                   |  21 +-
>  trace-events                                       |   8 +-
>  util/oslib-posix.c                                 |  16 +
>  util/oslib-win32.c                                 |   5 +
>  37 files changed, 2023 insertions(+), 862 deletions(-)
>  rename hw/mem/{pc-dimm.c => dimm.c} (65%)
>  create mode 100644 hw/mem/nvdimm/acpi.c
>  create mode 100644 hw/mem/nvdimm/internal.h
>  create mode 100644 hw/mem/nvdimm/namespace.c
>  create mode 100644 hw/mem/nvdimm/nvdimm.c
>  rewrite hw/mem/pc-dimm.c (91%)
>  rename include/hw/mem/{pc-dimm.h => dimm.h} (50%)
>  create mode 100644 include/hw/mem/nvdimm.h
>  rewrite include/hw/mem/pc-dimm.h (97%)
>  rename stubs/{qmp_pc_dimm_device_list.c => qmp_dimm_device_list.c} (56%)
>
> --
> 1.8.3.1
>
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