Re: [Qemu-devel] [PATCH 0/7 V11] nvdimm: guarantee persistence of QEMU writes to persistent memory

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Jul 27, 2018 at 01:49:17PM +0100, Stefan Hajnoczi wrote:
> On Wed, Jul 18, 2018 at 03:47:56PM +0800, junyan.he@gmx.com wrote:
> > From: Junyan He <junyan.he@intel.com>
> > 
> > QEMU writes to vNVDIMM backends in the vNVDIMM label emulation and live migration.
> > If the backend is on the persistent memory, QEMU needs to take proper operations to
> > ensure its writes persistent on the persistent memory. Otherwise, a host power failure
> > may result in the loss the guest data on the persistent memory.
> 
> Ping Michael.  Can this go through your tree?

OK but do you really think it's appropriate in this release cycle?
If not pls repost after the release including the acks.

> > 
> > This patch series is based on Marcel's patch "mem: add share parameter to memory-backend-ram" [1]
> > because of the changes in patch 1.
> > [1] https://lists.gnu.org/archive/html/qemu-devel/2018-02/msg03858.html
> > 
> > Previous versions of this patch series can be found at: 
> > v10: https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg03433.html
> > v9: https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg02361.html
> > v8: https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg02279.html
> > v7: https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg02997.html
> > v6: https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg00061.html
> > v5: https://lists.gnu.org/archive/html/qemu-devel/2018-05/msg02258.html
> > V4: https://lists.gnu.org/archive/html/qemu-devel/2018-02/msg06993.html
> > v3: https://lists.gnu.org/archive/html/qemu-devel/2018-02/msg04365.html
> > v2: https://lists.gnu.org/archive/html/qemu-devel/2018-02/msg01579.html
> > v1: https://lists.gnu.org/archive/html/qemu-devel/2017-12/msg05040.html
> > 
> > Changes in v11:
> > * (Patch 2) Modify the ram_flags parameter to 32bits, the same size as it in RAMBlock
> > * (Patch 5 and Patch 7) Delete pmem_xxx stub functions in stubs/pmem.c. Use inline
> > functions with assert to replace them, because we never come there when pmem is enabled
> > but lack of libpmem support.
> > 
> > Changes in v10:
> > * (Patch 4) Fix a nit in nvdimm docs about pmem option usage in command line 
> > The v10 patch set is all reviewed by Igor Mammedov <imammedo@redhat.com>
> > 
> > Changes in v9:
> > * (Patch 3 and Patch 4) Reorder these two patches to make logic right.
> > Firstly add libpmem support, and then we can use libpmem's configure
> > check result. Also fix some typo and grammar issues in these two patches.
> > 
> > Changs in v8: 
> > * (Patch 3) Report a error when user set 'pmem' to file-backend, while
> > the qemu is lack of libpmem support. In this case, we can not ensure
> > the persistence of the file-backend, so we choose to fail the build
> > rather than contine and make the thing more confused.
> > 
> > Changes in v7: 
> > The v6 patch set has already reviewed by Stefan Hajnoczi <stefanha@redhat.com>
> > No logic change in this v7 version, just:
> > * Spelling check and some document words refined.
> > * Rebase to "ram is migratable" patch set.
> > 
> > Changes in v6: 
> > * (Patch 1) Expose all ram block flags rather than redefine the flags.
> > * (Patch 4) Use pkg-config rather the hard check when configure. 
> > * (Patch 7) Sync and flush all the pmem data when migration completes,
> > rather than sync pages one by one in previous version.
> > 
> > Changes in v5: 
> > * (Patch 9) Add post copy check and output some messages for nvdimm.
> > 
> > Changes in v4: 
> > * (Patch 2) Fix compilation errors found by patchew.
> > 
> > Changes in v3:
> > * (Patch 5) Add a is_pmem flag to ram_handle_compressed() and handle
> > PMEM writes in it, so we don't need the _common function.
> > * (Patch 6) Expose qemu_get_buffer_common so we can remove the
> > unnecessary qemu_get_buffer_to_pmem wrapper.
> > * (Patch 8) Add a is_pmem flag to xbzrle_decode_buffer() and handle
> > PMEM writes in it, so we can remove the unnecessary
> > xbzrle_decode_buffer_{common, to_pmem}.
> > * Move libpmem stubs to stubs/pmem.c and fix the compilation failures
> > of test-{xbzrle,vmstate}.c.
> > 
> > Changes in v2:
> > * (Patch 1) Use a flags parameter in file ram allocation functions.
> > * (Patch 2) Add a new option 'pmem' to hostmem-file.
> > * (Patch 3) Use libpmem to operate on the persistent memory, rather
> > than re-implementing those operations in QEMU.
> > * (Patch 5-8) Consider the write persistence in the migration path.
> > 
> > 
> > Junyan:
> > [1/7] memory, exec: Expose all memory block related flags.
> > [6/7] migration/ram: Add check and info message to nvdimm post copy.
> > [7/7] migration/ram: ensure write persistence on loading all date to PMEM.
> > 
> > Haozhong:
> > [5/7] mem/nvdimm: ensure write persistence to PMEM in label emulation
> > 
> > Haozhong & Junyan:
> > [2/7] memory, exec: switch file ram allocation functions to 'flags' parameters
> > [3/7] configure: add libpmem support [4/7] hostmem-file: add the 'pmem' option
> > [4/7] hostmem-file: add the 'pmem' option
> > 
> > --
> > backends/hostmem-file.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
> > configure               | 29 +++++++++++++++++++++++++++++
> > docs/nvdimm.txt         | 22 ++++++++++++++++++++++
> > exec.c                  | 38 +++++++++++++-------------------------
> > hw/mem/nvdimm.c         |  9 ++++++++-
> > include/exec/memory.h   | 31 +++++++++++++++++++++++++++++--
> > include/exec/ram_addr.h | 28 ++++++++++++++++++++++++++--
> > include/qemu/pmem.h     | 36 ++++++++++++++++++++++++++++++++++++
> > memory.c                |  8 +++++---
> > migration/ram.c         | 17 +++++++++++++++++
> > numa.c                  |  2 +-
> > qemu-options.hx         |  7 +++++++
> > 12 files changed, 235 insertions(+), 36 deletions(-)
> > create mode 100644 include/qemu/pmem.h
> > 
> > -- 
> > 2.7.4
> > 
> >