This patch series adds several new API functions focused on enabling use
cases around reading and writing guest memory from QEMU plugins. To support
these new APIs, some utility functionality around retrieving information about
address spaces is added as well.
The new qemu_plugin_write_register utilizes gdb_write_register, which is now
declared in gdbstub.h for this purpose instead of being static.
qemu_plugin_write_memory_vaddr utilizes cpu_memory_rw_debug much the same as
the existing read_memory_vaddr function does.
The read and write_hwaddr functions are the most different. These functions
use address_space_rw, which works well in most cases. There is an important
caveat that for writes, the page being written will be set dirty by the
write operation. This dirty setting requires locking the page range,
which can contend with an already held lock in page_collection_lock
when called in a tb translate callback with a write to the instruction
memory in the tb. The doc comments warn against doing this, and it's unlikely
anyone would want to do this.
I've also added two test plugins: one that implements a simple hypercall
interface that guest code can use to communicate with the plugin in a
structured way with a test to ensure that this hypercall works and writing
virtual memory works. And one that implements a simple patch utility to patch
memory at runtime. The test for the second plugin ensures the patch applies
successfully to instruction memory, and can use both hw and vaddr methods.
I've had a few comments from the last submission that I've addressed, and some
that I haven't for one reason or another:
- Enforce QEMU_PLUGIN_CB_ flags in register read/write operations: done!
- Fix my commit messages and add long messages describing commits: done!
- Un-expose AS internals: done! Functions operate on current vCPU, current AS.
- Clean up use of current_cpu: done!
- Make functions take a vcpu_idx: not done. May revisit but it allows footguns.
Even for translation, seems best to not do this now. We can easily add _vcpu
versions of these functions in the future if we change our minds!
Rowan Hart (2):
plugins: Add enforcement of QEMU_PLUGIN_CB flags in register R/W
callbacks
plugins: Remove use of qemu_plugin_read_register where it is not
permitted
novafacing (7):
gdbstub: Expose gdb_write_register function to consumers of gdbstub
plugins: Add register write API
plugins: Add memory virtual address write API
plugins: Add memory hardware address read/write API
plugins: Add patcher plugin and test
plugins: Add hypercalls plugin and test
plugins: Update plugin version and add notes
accel/tcg/plugin-gen.c | 27 +
gdbstub/gdbstub.c | 2 +-
include/exec/gdbstub.h | 14 +
include/qemu/plugin.h | 12 +
include/qemu/qemu-plugin.h | 166 +++++-
plugins/api.c | 135 ++++-
plugins/core.c | 60 +-
tests/tcg/Makefile.target | 2 +
tests/tcg/plugins/hypercalls.c | 552 ++++++++++++++++++
tests/tcg/plugins/insn.c | 22 +-
tests/tcg/plugins/meson.build | 2 +-
tests/tcg/plugins/patch.c | 302 ++++++++++
tests/tcg/x86_64/Makefile.softmmu-target | 36 +-
tests/tcg/x86_64/system/hypercalls-target.c | 45 ++
tests/tcg/x86_64/system/patch-target.c | 32 +
.../tcg/x86_64/system/validate-hypercalls.py | 40 ++
tests/tcg/x86_64/system/validate-patch.py | 39 ++
17 files changed, 1438 insertions(+), 50 deletions(-)
create mode 100644 tests/tcg/plugins/hypercalls.c
create mode 100644 tests/tcg/plugins/patch.c
create mode 100644 tests/tcg/x86_64/system/hypercalls-target.c
create mode 100644 tests/tcg/x86_64/system/patch-target.c
create mode 100755 tests/tcg/x86_64/system/validate-hypercalls.py
create mode 100755 tests/tcg/x86_64/system/validate-patch.py
--
2.49.0
