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[v2,0/1] plugins: add API to read guest CPU memory from hwaddr

Message ID 20240829164751.9504-1-rowanbhart@gmail.com (mailing list archive)
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Series plugins: add API to read guest CPU memory from hwaddr | expand

Message

Rowan Hart Aug. 29, 2024, 4:47 p.m. UTC 
This patch adds a single API function which allows reading from a guest
CPU physical address.

I don't know of a good way to add a self-contained test for this feature
to tests/tcg/plugins, but I did come up with a small test case to
demonstrate the functionality using peiyuanix/riscv-os:

First, grab and build the firmware code:

curl -o firmware.S https://raw.githubusercontent.com/peiyuanix/riscv-os/main/03-Bare-Metal-Hello-RISC-V/firmware.s
curl -o firmware.x https://raw.githubusercontent.com/peiyuanix/riscv-os/main/03-Bare-Metal-Hello-RISC-V/firmware.ld
riscv64-linux-gnu-as firmware.S -o firmware.o
riscv64-linux-gnu-ld -T firmware.x -o firmare firmware.o
riscv64-linux-gnu-objcopy -O binary -S firmware firmware.bin

Next, grab and build the plugin (just dumps from phys address on first
instruction executed):

curl -o dump-riscv-firmware.c https://gist.githubusercontent.com/novafacing/5abc08052fab671a0fb26547810b4c55/raw/33772d614d6e36eae30e3405af34f149d7cc608b/dump-riscv-firmware.c
gcc -rdynamic -shared -fPIC -Iinclude/qemu $(pkg-config --cflags --libs glib-2.0) -o libdump-riscv-firmware.so dump-riscv-firmware.c

Finally, run the plugin:

qemu-system-riscv64 -display none -machine virt -serial stdio -bios firmware.bin -plugin $(pwd)libdump-riscv-firmware.so -d plugin

This outputs as expected -- the hexdump of the running firmware:

b7 01 00 10 a3 80 01 00 93 02 00 08 a3 81 51 00  | ..............Q.
93 02 50 00 23 80 51 00 93 02 00 00 a3 80 51 00  | ..P.#.Q.......Q.
93 02 30 00 a3 81 51 00 93 02 10 00 23 81 51 00  | ..0...Q.....#.Q.
23 82 01 00 83 82 51 00 83 82 01 00 a3 83 01 00  | #.....Q.........
93 02 80 04 23 80 51 00 93 02 50 06 23 80 51 00  | ....#.Q...P.#.Q.
93 02 c0 06 23 80 51 00 93 02 c0 06 23 80 51 00  | ....#.Q.....#.Q.
93 02 f0 06 23 80 51 00 93 02 c0 02 23 80 51 00  | ....#.Q.....#.Q.
93 02 00 02 23 80 51 00 93 02 20 05 23 80 51 00  | ....#.Q.....#.Q.
93 02 90 04 23 80 51 00 93 02 30 05 23 80 51 00  | ....#.Q...0.#.Q.
93 02 30 04 23 80 51 00 93 02 d0 02 23 80 51 00  | ..0.#.Q.....#.Q.
93 02 60 05 23 80 51 00 93 02 10 02 23 80 51 00  | ..`.#.Q.....#.Q.
93 02 a0 00 23 80 51 00 6f 00 00 00 00 00 00 00  | ....#.Q.o.......
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  | ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  | ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  | ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  | ................
Hello, RISC-V!

For v2, removes a symbol left in qemu-plugins.symbols accidentally.

Rowan Hart (1):
  plugins: add API to read guest CPU memory from hwaddr

 include/qemu/qemu-plugin.h   | 22 ++++++++++++++++++++++
 plugins/api.c                | 17 +++++++++++++++++
 plugins/qemu-plugins.symbols |  1 +
 3 files changed, 40 insertions(+)