[Qemu-devel] [RFC][PATCH v2 0/6] backdoor: instruction-based guest-to-QEMU backdoor communication channel

[Lluís]

Provides the ability for the guest to communicate with user-provided code inside
QEMU itself.

This backdoor communication channel is based on using instructions, as opposed
to methods based on MMIO/PIO or virtproxy/virtagent.

Then, these instructions are redirected to a set of user-provided routines,
which are expected to be in the static library "libbackdoor.a", identified by
the "--with-backdoor" configuration parameter.

The advantages of this method are:

* Minimal setup for the guest. Can be used with a simple library using
  LD_PRELOAD, or simply adding calls to the macros in "backdoor/guest.h".

* Low-overhead. Using instructions does not go through any OS abstraction, not
  even for the setup of the communication channel.

* Non-intrusive wrt OS. It can be used on any OS without prior modifications.

When possible, this will overload unused/meaningless instructions in order to
let the modified guest application to run natively without errors (e.g., using
the CPUID instruction in x86 systems).

v2:

Rebase onto latest QEMU version (d33ea50a958b2e050d2b28e5f17e3b55e91c6d74).

Signed-off-by: Lluís Vilanova <address@hidden>
---

Lluís Vilanova (6):
      [arm m68k] move helpers.h to helper.h
      backdoor: handle config-time activation
      backdoor: declare host-side backdoor helpers
      backdoor: declare guest-side interface macros
      backdoor: [i386] provide and implement intruction-based backdoor interface
      backdoor: add a simple example


 .gitignore                             |    1 
 Makefile.target                        |   40 +++
 backdoor/examples/print/README         |   13 +
 backdoor/examples/print/guest/Makefile |    7 
 backdoor/examples/print/guest/test.c   |   33 ++
 backdoor/examples/print/host/Makefile  |   13 +
 backdoor/examples/print/host/printcb.c |   36 +++
 backdoor/guest.h                       |   54 ++++
 backdoor/helper.h                      |   21 +
 configure                              |   21 +
 target-arm/helper.c                    |    2 
 target-arm/helper.h                    |  450 ++++++++++++++++++++++++++++++++
 target-arm/helpers.h                   |  450 --------------------------------
 target-arm/iwmmxt_helper.c             |    2 
 target-arm/neon_helper.c               |    2 
 target-arm/op_helper.c                 |    2 
 target-arm/translate.c                 |    6 
 target-i386/cpuid.c                    |   27 ++
 target-i386/helper.h                   |    4 
 target-i386/translate.c                |    4 
 target-m68k/helper.c                   |    2 
 target-m68k/helper.h                   |   54 ++++
 target-m68k/helpers.h                  |   54 ----
 target-m68k/op_helper.c                |    2 
 target-m68k/translate.c                |    6 
 25 files changed, 786 insertions(+), 520 deletions(-)
 create mode 100644 backdoor/examples/print/README
 create mode 100644 backdoor/examples/print/guest/Makefile
 create mode 100644 backdoor/examples/print/guest/test.c
 create mode 100644 backdoor/examples/print/host/Makefile
 create mode 100644 backdoor/examples/print/host/printcb.c
 create mode 100644 backdoor/guest.h
 create mode 100644 backdoor/helper.h
 create mode 100644 target-arm/helper.h
 delete mode 100644 target-arm/helpers.h
 create mode 100644 target-m68k/helper.h
 delete mode 100644 target-m68k/helpers.h