Re: [Qemu-devel] [PATCH 00/21] WIP: dump: add kaslr support (for after 2.9)

[Dave Anderson <anderson@redhat.com>]

----- Original Message -----
> Hi,
> 
> Latest linux kernel enabled kaslr to randomize phys/virt memory
> addresses. There has been some effort to support kexec/kdump so that
> crash utility can still works in case crashed kernel has kaslr
> enabled.
> 
> This series aims to provide enough information in qemu dumps so that
> crash utility can work with kaslr kernel too, with x86_64 guests (it
> hasn't been tested on other archs, help welcome).
> 
> Two pieces of informations are necessary: the phys_base (the physical
> address where the kernel is loaded) and the kaslr offset. Other useful
> informations for debugging are provided in Linux vmcoreinfo too.
> 
> There has been discussions to provide those details in early boot,
> with ACPI, fw_cfg, virtio-pstore etc, but none has reached a consensus
> yet. A possiblity for now is to provide the information when qemu-ga
> starts. This has the advantage of working with older guests and may
> not be incompatible with future methods (in this case it could ignore
> qga info for example). The drawback is that qemu will have to parse
> the json stream. For now it stops processing it whem VMDUMP_INFO is
> received. It would be wise to introduce a QMP welcome message, so that
> qemu would stop immediately processing the stream if the agent doesn't
> have the event. Another option is to create a seperate channel...
> I welcome other ideas and discussion.
> 
> crash upstream doesn't yet parse NUMBER(phys_base). You may pass it to
> crash with --machdep phys_base=0x.. provided you snooped on qga.

FYI: a patch to utilize NUMBER(phys_base) has been checked in upstream:

  https://github.com/crash-utility/crash/commit/ed60e97e319a1cfc9e2779aa1baac305677393d8

  Linux 4.10 commit 401721ecd1dcb0a428aa5d6832ee05ffbdbffbbe finally
  exports the x86_64 "phys_base" value in the VMCOREINFO note, so
  utilize it whenever it exists.
  (anderson@redhat.com)

Thanks,
  Dave


> kdump kaslr-dumps should now work with crash out of the box.
> 
> A large part of the series has to do with json and the qobject type
> system to deal with uint64 values, so that addresses can now be sent
> over json. The second halfs adds qga VMDUMP_INFO event, and ELF/kdump
> dumping. Depending on the feedback, I will probably split the series,
> but for those who would like to try it, help or suggest ideas, here is
> the whole thing.
> 
> cheers
> 
> Marc-André Lureau (21):
>   qapi: add info comment for generated types
>   pci-host: use more specific type names
>   object: fix potential leak in getters
>   qobject: add quint type
>   qapi: update the qobject visitor to use QUInt
>   json: learn to parse uint64 numbers
>   object: add uint property setter/getter
>   qdev: use int and uint properties
>   qdev: use appropriate type
>   Use uint property getter/setter where appropriate
>   qdict: learn to lookup quint
>   test-qga: drop everything until guest-sync
>   qga: report error on keyfile dump error
>   qga: add and populate VMDumpInfo
>   qga: register event emit function
>   qga: emit VMDUMP_INFO event
>   virtio-channel: parse qga stream for VMDUMP_INFO event
>   dump: use qga VMDUMP_INFO for ELF dump
>   kdump: write vmcoreinfo in header
>   scripts/dump-guest-memory.py: fix int128_get64 on recent gcc
>   scripts/dump-guest-memory.py: add VMCOREINFO
> 
>  qapi/introspect.json                     |   2 +-
>  scripts/qapi.py                          |  39 ++++---
>  scripts/dump-guest-memory.py             |  66 ++++++++++-
>  scripts/qapi-event.py                    |   4 +-
>  scripts/qapi-types.py                    |  17 +--
>  scripts/qapi-visit.py                    |   3 +-
>  include/hw/isa/isa.h                     |   2 +-
>  include/hw/qdev-core.h                   |   5 +-
>  include/hw/qdev-properties.h             |  59 ++++++----
>  include/qapi/qmp/qdict.h                 |   2 +
>  include/qapi/qmp/quint.h                 |  25 +++++
>  include/qapi/qmp/types.h                 |   1 +
>  include/qom/object.h                     |  23 ++++
>  include/sysemu/dump-info.h               |  15 +++
>  include/sysemu/dump.h                    |   2 +
>  qga/guest-agent-core.h                   |   2 +
>  block/qapi.c                             |   5 +
>  dump.c                                   | 184
>  ++++++++++++++++++++++++++++++-
>  hw/acpi/memory_hotplug.c                 |  10 +-
>  hw/acpi/nvdimm.c                         |  10 +-
>  hw/acpi/pcihp.c                          |   6 +-
>  hw/arm/aspeed.c                          |   4 +-
>  hw/arm/bcm2835_peripherals.c             |   9 +-
>  hw/arm/raspi.c                           |   4 +-
>  hw/block/fdc.c                           |  54 ++++-----
>  hw/char/virtio-console.c                 |  53 +++++++++
>  hw/core/platform-bus.c                   |   2 +-
>  hw/core/qdev-properties.c                |   8 +-
>  hw/core/qdev.c                           |   8 +-
>  hw/i386/acpi-build.c                     |  70 ++++++------
>  hw/i386/pc.c                             |   6 +-
>  hw/intc/arm_gicv3_common.c               |   2 +-
>  hw/mem/pc-dimm.c                         |   5 +-
>  hw/misc/auxbus.c                         |   2 +-
>  hw/misc/pvpanic.c                        |   2 +-
>  hw/net/e1000e.c                          |  14 +--
>  hw/pci-host/gpex.c                       |   2 +-
>  hw/pci-host/piix.c                       |   8 +-
>  hw/pci-host/q35.c                        |  12 +-
>  hw/pci-host/xilinx-pcie.c                |   2 +-
>  hw/ppc/pnv_core.c                        |   2 +-
>  hw/ppc/spapr.c                           |   8 +-
>  numa.c                                   |   6 +-
>  qapi/qobject-input-visitor.c             |  30 ++++-
>  qapi/qobject-output-visitor.c            |   3 +-
>  qga/channel-posix.c                      |  11 ++
>  qga/main.c                               | 162 ++++++++++++++++++++++++++-
>  qobject/json-lexer.c                     |   4 +
>  qobject/json-parser.c                    |  19 +++-
>  qobject/qdict.c                          |  37 ++++++-
>  qobject/qjson.c                          |   8 ++
>  qobject/qobject.c                        |   1 +
>  qobject/quint.c                          |  58 ++++++++++
>  qom/object.c                             |  38 ++++++-
>  target/i386/cpu.c                        |   6 +-
>  tests/check-qdict.c                      |  31 ++++++
>  tests/check-qint.c                       |  59 ++++++++++
>  tests/check-qjson.c                      |  28 +++++
>  tests/test-qga.c                         |  27 +++--
>  tests/test-qobject-input-visitor.c       |  15 +++
>  tests/test-qobject-output-visitor.c      |  19 +++-
>  ui/console.c                             |   4 +-
>  util/qemu-option.c                       |   6 +
>  xen-hvm.c                                |   6 +-
>  Makefile                                 |   7 +-
>  qga/Makefile.objs                        |   1 +
>  qga/qapi-schema.json                     |  15 +++
>  qobject/Makefile.objs                    |   2 +-
>  tests/qapi-schema/comments.out           |   2 +-
>  tests/qapi-schema/empty.out              |   2 +-
>  tests/qapi-schema/event-case.out         |   2 +-
>  tests/qapi-schema/ident-with-escape.out  |   2 +-
>  tests/qapi-schema/include-relpath.out    |   2 +-
>  tests/qapi-schema/include-repetition.out |   2 +-
>  tests/qapi-schema/include-simple.out     |   2 +-
>  tests/qapi-schema/indented-expr.out      |   2 +-
>  tests/qapi-schema/qapi-schema-test.out   |   2 +-
>  77 files changed, 1153 insertions(+), 227 deletions(-)
>  create mode 100644 include/qapi/qmp/quint.h
>  create mode 100644 include/sysemu/dump-info.h
>  create mode 100644 qobject/quint.c
> 
> --
> 2.12.0.191.gc5d8de91d
> 
>