Pierrick Bouvier <pierrick.bouv...@linaro.org> writes: > On 6/11/25 4:24 PM, Rowan Hart wrote: >> 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. >> For v3, 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! >> For v5, I've just updated the enforcement of the QEMU_PLUGIN_CB_ >> flags to just >> use immediate stores, which simplifies the implementation quite a lot and >> should be more efficient too. Thanks Pierrick for the suggestion! >> v6 is a formatting pass, I left some whitespace that needed removal, >> some >> license text was wrong, and so forth. >> v8 reverts a mistake I made extending the size of arrays of >> TCGHelperInfo >> structs, as I misunderstood their sizes. It preserves adding an explicit >> zero as the last entry for clarity, however. >> v9 fixes qemu_plugin_read_register to return -1 on parameter or flag >> state >> error instead of 0. >> In v10, I relaxed the restriction on when the register r/w functions >> can be >> called, allowing all them to be used from any callback where the CPU is not >> currently executing, with additional notes in the documentation for >> exceptions >> (atexit and flush, which do not operate on a specific CPU and in which >> current_cpu is not set). >> v11 makes the cb flags functions inline and fixes a typo where cpu >> was asserted >> but current_cpu was actually accessed. >> v12 removes the hypercalls plugin because the functions it tested >> are also >> tested by the patcher plugin, making it redundant. We'll circle back on a >> hypercalls API in the future as a part of the plugin API, not as a plugin >> itself. >> Rowan Hart (1): >> plugins: Add enforcement of QEMU_PLUGIN_CB flags in register R/W >> callbacks >> novafacing (6): >> 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: Update plugin version and add notes >> accel/tcg/plugin-gen.c | 30 +++ >> gdbstub/gdbstub.c | 2 +- >> include/exec/gdbstub.h | 14 ++ >> include/hw/core/cpu.h | 1 + >> include/qemu/plugin.h | 15 ++ >> include/qemu/qemu-plugin.h | 176 ++++++++++++++-- >> plugins/api.c | 135 +++++++++++- >> plugins/core.c | 33 +++ >> tests/tcg/Makefile.target | 1 + >> tests/tcg/plugins/meson.build | 2 +- >> tests/tcg/plugins/patch.c | 241 ++++++++++++++++++++++ >> tests/tcg/x86_64/Makefile.softmmu-target | 32 ++- >> tests/tcg/x86_64/system/patch-target.c | 27 +++ >> tests/tcg/x86_64/system/validate-patch.py | 39 ++++ >> 14 files changed, 725 insertions(+), 23 deletions(-) >> create mode 100644 tests/tcg/plugins/patch.c >> create mode 100644 tests/tcg/x86_64/system/patch-target.c >> create mode 100755 tests/tcg/x86_64/system/validate-patch.py >> > > @Alex, > series looks good to me now. > > Would you like to add comments, or is it good for you also?
I'll do a pass through next week but I think we are in good shape. > > Thanks, > Pierrick -- Alex Bennée Virtualisation Tech Lead @ Linaro
