On 2/24/26 7:58 AM, Florian Hofhammer wrote:
This commit tests the readonly feature for registers exposed via the
plugin API introduced earlier in the patch series.
Signed-off-by: Florian Hofhammer <[email protected]>
---
tests/tcg/plugins/meson.build | 1 +
tests/tcg/plugins/registers.c | 68 +++++++++++++++++++++++++++++++++++
2 files changed, 69 insertions(+)
create mode 100644 tests/tcg/plugins/registers.c
diff --git a/tests/tcg/plugins/meson.build b/tests/tcg/plugins/meson.build
index c5e49753fd..5005aa8dc9 100644
--- a/tests/tcg/plugins/meson.build
+++ b/tests/tcg/plugins/meson.build
@@ -6,6 +6,7 @@ test_plugins = [
'insn.c',
'mem.c',
'patch.c',
+'registers.c',
'reset.c',
'syscall.c',
]
diff --git a/tests/tcg/plugins/registers.c b/tests/tcg/plugins/registers.c
new file mode 100644
index 0000000000..a7bd692225
--- /dev/null
+++ b/tests/tcg/plugins/registers.c
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2026, Florian Hofhammer <[email protected]>
+ *
+ * License: GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#include "glib.h"
+#include <inttypes.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#include <qemu-plugin.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+/*
+ * This callback is called when a vCPU is initialized. It tests whether we
+ * successfully read from a register and write value back to it. It also tests
+ * that read-only registers cannot be written to, i.e., we can read a read-only
+ * register but writing to it fails.
+ */
+static void vcpu_init_cb(qemu_plugin_id_t id, unsigned int vcpu_index)
+{
+ g_autoptr(GArray) regs = qemu_plugin_get_registers();
+ g_autoptr(GByteArray) buf = g_byte_array_sized_new(0);
+ bool success = false;
+
+ /* Make sure we can read and write an arbitrary register */
+ qemu_plugin_reg_descriptor *reg_desc = &g_array_index(regs,
+ qemu_plugin_reg_descriptor, 0);
+ g_assert(reg_desc->is_readonly == false);
+ success = qemu_plugin_read_register(reg_desc->handle, buf);
+ g_assert(success);
+ success = qemu_plugin_write_register(reg_desc->handle, buf);
+ g_assert(success);
+
+ /*
+ * Reset the buffer and find a read-only register. On each architecture, at
+ * least the PC should be read-only because it's only supposed to be
+ * modified via the qemu_plugin_set_pc() function.
+ */
+ g_byte_array_set_size(buf, 0);
+ for (size_t i = 0; i < regs->len; i++) {
+ reg_desc = &g_array_index(regs, qemu_plugin_reg_descriptor, i);
+ if (reg_desc->is_readonly) {
+ success = qemu_plugin_read_register(reg_desc->handle, buf);
+ g_assert(success);
+ break;
+ } else {
+ reg_desc = NULL;
+ }
+ }
+ /* Make sure there is a read-only register and we cannot write to it */
+ g_assert(reg_desc != NULL);
+ success = qemu_plugin_write_register(reg_desc->handle, buf);
+ g_assert(!success);
+}
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
+ const qemu_info_t *info,
+ int argc, char **argv)
+{
+ qemu_plugin_register_vcpu_init_cb(id, vcpu_init_cb);
+ return 0;
+}
Looks great, and nice to have a test for this.
Reviewed-by: Pierrick Bouvier <[email protected]>
