[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v8 0/5] implement vNVDIMM
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v8 0/5] implement vNVDIMM |
Date: |
Mon, 30 Nov 2015 12:38:47 +0200 |
On Mon, Nov 16, 2015 at 06:50:58PM +0800, Xiao Guangrong wrote:
> This patchset can be found at:
> https://github.com/xiaogr/qemu.git nvdimm-v8
>
> It is based on pci branch on Michael's tree and the top commit is:
> commit e3a4e177d9 (migration/ram: fix build on 32 bit hosts).
>
> Changelog in v8:
> We split the long patch series into the small parts, as you see now, this
> is the first part which enables NVDIMM without label data support.
Finally found some time to review this. Very nice, this is making good
progress, and I think to split it like this is a great idea. I sent
some comments, most of them minor.
Thanks!
> The command line has been changed because some patches simplifying the
> things have not been included into this series, you should specify the
> file size exactly using the parameters as follows:
> memory-backend-file,id=mem1,share,mem-path=/tmp/nvdimm1,size=10G \
> -device nvdimm,memdev=mem1,id=nv1
>
> Changelog in v7:
> - changes from Vladimir Sementsov-Ogievskiy's comments:
> 1) let gethugepagesize() realize if fstat is failed instead of get
> normal page size
> 2) rename open_file_path to open_ram_file_path
> 3) better log the error message by using error_setg_errno
> 4) update commit in the commit log to explain hugepage detection on
> Windows
>
> - changes from Eduardo Habkost's comments:
> 1) use 'Error**' to collect error message for qemu_file_get_page_size()
> 2) move gethugepagesize() replacement to the same patch to make it
> better for review
> 3) introduce qemu_get_file_size to unity the code with raw_getlength()
>
> - changes from Stefan's comments:
> 1) check the memory region is large enough to contain DSM output
> buffer
>
> - changes from Eric Blake's comments:
> 1) update the shell command in the commit log to generate the patch
> which drops 'pc-dimm' prefix
>
> - others:
> pick up Reviewed-by from Stefan, Vladimir Sementsov-Ogievskiy, and
> Eric Blake.
>
> Changelog in v6:
> - changes from Stefan's comments:
> 1) fix code style of struct naming by CamelCase way
> 2) fix offset + length overflow when read/write label data
> 3) compile hw/acpi/nvdimm.c for per target so that TARGET_PAGE_SIZE can
> be used to replace getpagesize()
>
> Changelog in v5:
> - changes from Michael's comments:
> 1) prefix nvdimm_ to everything in NVDIMM source files
> 2) make parsing _DSM Arg3 more clear
> 3) comment style fix
> 5) drop single used definition
> 6) fix dirty dsm buffer lost due to memory write happened on host
> 7) check dsm buffer if it is big enough to contain input data
> 8) use build_append_int_noprefix to store single value to GArray
>
> - changes from Michael's and Igor's comments:
> 1) introduce 'nvdimm-support' parameter to control nvdimm
> enablement and it is disabled for 2.4 and its earlier versions
> to make live migration compatible
> 2) only reserve 1 RAM page and 4 bytes IO Port for NVDIMM ACPI
> virtualization
>
> - changes from Stefan's comments:
> 1) do endian adjustment for the buffer length
>
> - changes from Bharata B Rao's comments:
> 1) fix compile on ppc
>
> - others:
> 1) the buffer length is directly got from IO read rather than got
> from dsm memory
> 2) fix dirty label data lost due to memory write happened on host
>
> Changelog in v4:
> - changes from Michael's comments:
> 1) show the message, "Memory is not allocated from HugeTlbfs", if file
> based memory is not allocated from hugetlbfs.
> 2) introduce function, acpi_get_nvdimm_state(), to get NVDIMMState
> from Machine.
> 3) statically define UUID and make its operation more clear
> 4) use GArray to build device structures to avoid potential buffer
> overflow
> 4) improve comments in the code
> 5) improve code style
>
> - changes from Igor's comments:
> 1) add NVDIMM ACPI spec document
> 2) use serialized method to avoid Mutex
> 3) move NVDIMM ACPI's code to hw/acpi/nvdimm.c
> 4) introduce a common ASL method used by _DSM for all devices to reduce
> ACPI size
> 5) handle UUID in ACPI AML code. BTW, i'd keep handling revision in QEMU
> it's better to upgrade QEMU to support Rev2 in the future
>
> - changes from Stefan's comments:
> 1) copy input data from DSM memory to local buffer to avoid potential
> issues as DSM memory is visible to guest. Output data is handled
> in a similar way
>
> - changes from Dan's comments:
> 1) drop static namespace as Linux has already supported label-less
> nvdimm devices
>
> - changes from Vladimir's comments:
> 1) print better message, "failed to get file size for %s, can't create
> backend on it", if any file operation filed to obtain file size
>
> - others:
> create a git repo on github.com for better review/test
>
> Also, thanks for Eric Blake's review on QAPI's side.
>
> Thank all of you to review this patchset.
>
> 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
>
> Xiao Guangrong (5):
> nvdimm: implement NVDIMM device abstract
> acpi: support specified oem table id for build_header
> nvdimm acpi: build ACPI NFIT table
> nvdimm acpi: build ACPI nvdimm devices
> nvdimm: add maintain info
>
> MAINTAINERS | 7 +
> default-configs/i386-softmmu.mak | 2 +
> default-configs/x86_64-softmmu.mak | 2 +
> hw/acpi/Makefile.objs | 1 +
> hw/acpi/aml-build.c | 15 +-
> hw/acpi/ich9.c | 19 ++
> hw/acpi/memory_hotplug.c | 5 +
> hw/acpi/nvdimm.c | 467
> +++++++++++++++++++++++++++++++++++++
> hw/acpi/piix4.c | 4 +
> hw/arm/virt-acpi-build.c | 13 +-
> hw/i386/acpi-build.c | 26 ++-
> hw/mem/Makefile.objs | 1 +
> hw/mem/nvdimm.c | 46 ++++
> include/hw/acpi/aml-build.h | 3 +-
> include/hw/acpi/ich9.h | 3 +
> include/hw/i386/pc.h | 12 +-
> include/hw/mem/nvdimm.h | 41 ++++
> 17 files changed, 645 insertions(+), 22 deletions(-)
> create mode 100644 hw/acpi/nvdimm.c
> create mode 100644 hw/mem/nvdimm.c
> create mode 100644 include/hw/mem/nvdimm.h
>
> --
> 1.8.3.1
- Re: [Qemu-devel] [PATCH v8 4/5] nvdimm acpi: build ACPI nvdimm devices, (continued)
Re: [Qemu-devel] [PATCH v8 0/5] implement vNVDIMM, Stefan Hajnoczi, 2015/11/30
Re: [Qemu-devel] [PATCH v8 0/5] implement vNVDIMM,
Michael S. Tsirkin <=