Re: [PATCH v3 00/20] virtio-mem: Paravirtualized memory hot(un)plug

Michael S. Tsirkin
2020-06-09T13:11:43Z

On Wed, Jun 03, 2020 at 04:48:54PM +0200, David Hildenbrand wrote:
> This is the very basic, initial version of virtio-mem. More info on
> virtio-mem in general can be found in the Linux kernel driver v2 posting
> [1] and in patch #10. The latest Linux driver v4 can be found at [2].
>
> This series is based on [3]:
> "[PATCH v1] pc: Support coldplugging of virtio-pmem-pci devices on all
> buses"
>
> The patches can be found at:
> https://github.com/davidhildenbrand/qemu.git virtio-mem-v3

So given we tweaked the config space a bit, this needs a respin.

> "The basic idea of virtio-mem is to provide a flexible,
> cross-architecture memory hot(un)plug solution that avoids many limitations
> imposed by existing technologies, architectures, and interfaces."
>
> There are a lot of addons in the works (esp. protection of unplugged
> memory, better hugepage support (esp. when reading unplugged memory),
> resizeable memory backends, support for more architectures, ...), this is
> the very basic version to get the ball rolling.
>
> The first 8 patches make sure we don't have any sudden surprises e.g., if
> somebody tries to pin all memory in RAM blocks, resulting in a higher
> memory consumption than desired. The remaining patches add basic virtio-mem
> along with support for x86-64.
>
>
> Note: Since commit 7d2ef6dcc1cf ("hmp: Simplify qom-set"), the behavior of
> qom-set changed and we can no longer pass proper sizes (e.g., 300M). The
> description in patch #10 is outdated - but I hope that we'll bring back the
> old behaviour, so I kept it for now :)
>
> [1] https://lkml.kernel.org/r/20200311171422.10484-1-david@redhat.com
> [2] https://lkml.kernel.org/r/20200507140139.17083-1-david@redhat.com
> [3] https://lkml.kernel.org/r/20200525084511.51379-1-david@redhat.com
>
> Cc: teawater <teawaterz@linux.alibaba.com>
> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
>
> v2 -> v3:
> - Rebased on upstream/[3]
> - "virtio-mem: Exclude unplugged memory during migration"
> -- Added
> - "virtio-mem: Paravirtualized memory hot(un)plug"
> -- Simplify bitmap operations, find consecutive areas
> -- Tweak error messages
> -- Reshuffle some checks
> -- Minor cleanups
> - "accel/kvm: Convert to ram_block_discard_disable()"
> - "target/i386: sev: Use ram_block_discard_disable()"
> -- Keep asserts clean of functional things
>
> v1 -> v2:
> - Rebased to object_property_*() changes
> - "exec: Introduce ram_block_discard_(disable|require)()"
> -- Change the function names and rephrase/add comments
> - "virtio-balloon: Rip out qemu_balloon_inhibit()"
> -- Add and use "migration_in_incoming_postcopy()"
> - "migration/rdma: Use ram_block_discard_disable()"
> -- Add a comment regarding pin_all vs. !pin_all
> - "virtio-mem: Paravirtualized memory hot(un)plug"
> -- Replace virtio_mem_discard_inhibited() by
> migration_in_incoming_postcopy()
> -- Drop some asserts
> -- Drop virtio_mem_bad_request(), use virtio_error() directly, printing
> more information
> -- Replace "Note: Discarding should never fail ..." comments by
> error_report()
> -- Replace virtio_stw_p() by cpu_to_le16()
> -- Drop migration_addr and migration_block_size
> -- Minor cleanups
> - "linux-headers: update to contain virtio-mem"
> -- Updated to latest v4 in Linux
> - General changes
> -- Fixup the users of the renamed ram_block_discard_(disable|require)
> -- Use "X: cannot disable RAM discard"-styled error messages
> - Added
> -- "virtio-mem: Migration sanity checks"
> -- "virtio-mem: Add trace events"
>
> David Hildenbrand (20):
> exec: Introduce ram_block_discard_(disable|require)()
> vfio: Convert to ram_block_discard_disable()
> accel/kvm: Convert to ram_block_discard_disable()
> s390x/pv: Convert to ram_block_discard_disable()
> virtio-balloon: Rip out qemu_balloon_inhibit()
> target/i386: sev: Use ram_block_discard_disable()
> migration/rdma: Use ram_block_discard_disable()
> migration/colo: Use ram_block_discard_disable()
> linux-headers: update to contain virtio-mem
> virtio-mem: Paravirtualized memory hot(un)plug
> virtio-pci: Proxy for virtio-mem
> MAINTAINERS: Add myself as virtio-mem maintainer
> hmp: Handle virtio-mem when printing memory device info
> numa: Handle virtio-mem in NUMA stats
> pc: Support for virtio-mem-pci
> virtio-mem: Allow notifiers for size changes
> virtio-pci: Send qapi events when the virtio-mem size changes
> virtio-mem: Migration sanity checks
> virtio-mem: Add trace events
> virtio-mem: Exclude unplugged memory during migration
>
> MAINTAINERS | 8 +
> accel/kvm/kvm-all.c | 4 +-
> balloon.c | 17 -
> exec.c | 52 ++
> hw/core/numa.c | 6 +
> hw/i386/Kconfig | 1 +
> hw/i386/pc.c | 49 +-
> hw/s390x/s390-virtio-ccw.c | 22 +-
> hw/vfio/ap.c | 10 +-
> hw/vfio/ccw.c | 11 +-
> hw/vfio/common.c | 53 +-
> hw/vfio/pci.c | 6 +-
> hw/virtio/Kconfig | 11 +
> hw/virtio/Makefile.objs | 2 +
> hw/virtio/trace-events | 10 +
> hw/virtio/virtio-balloon.c | 8 +-
> hw/virtio/virtio-mem-pci.c | 157 ++++
> hw/virtio/virtio-mem-pci.h | 34 +
> hw/virtio/virtio-mem.c | 876 ++++++++++++++++++++
> include/exec/memory.h | 41 +
> include/hw/pci/pci.h | 1 +
> include/hw/vfio/vfio-common.h | 4 +-
> include/hw/virtio/virtio-mem.h | 86 ++
> include/migration/colo.h | 2 +-
> include/migration/misc.h | 2 +
> include/standard-headers/linux/virtio_ids.h | 1 +
> include/standard-headers/linux/virtio_mem.h | 211 +++++
> include/sysemu/balloon.h | 2 -
> migration/migration.c | 15 +-
> migration/postcopy-ram.c | 23 -
> migration/rdma.c | 18 +-
> migration/savevm.c | 11 +-
> monitor/hmp-cmds.c | 16 +
> monitor/monitor.c | 1 +
> qapi/misc.json | 64 +-
> target/i386/sev.c | 7 +
> 36 files changed, 1721 insertions(+), 121 deletions(-)
> create mode 100644 hw/virtio/virtio-mem-pci.c
> create mode 100644 hw/virtio/virtio-mem-pci.h
> create mode 100644 hw/virtio/virtio-mem.c
> create mode 100644 include/hw/virtio/virtio-mem.h
> create mode 100644 include/standard-headers/linux/virtio_mem.h
>
> --
> 2.25.4