Commit 33e7c328e0 for qemu.org

commit 33e7c328e0ed776703fd4dc0ff222194e70f601d
Author: Aleksandr Sergeev <sergeev0xef@gmail.com>
Date:   Wed Oct 28 10:23:08 2026 +0300

    accel/tcg: Fix false awakening of gdb

    In qemu there is a mechanism to cancel execution of tb.
    If `cpu->neg.icount_decr` is <0, translation block
    will exit in prolog.
    E.g. such may happen when RCU thread kicks out vCPU.

    If tb is not executed, we shall not raise EXCP_DEBUG,
    because no step actually happened.

    Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4766
    Signed-off-by: Aleksandr Sergeev <sergeev0xef@gmail.com>
    Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
    Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
    Message-ID: <20261028072308.839836-1-al.sergeev@syntacore.com>

diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 9ead35418d..4497701486 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -478,16 +478,16 @@ cpu_tb_exec(CPUState *cpu, TranslationBlock *itb, int *tb_exit)
                          last_tb->tc.ptr, pc, lookup_symbol(pc));
             }
         }
-    }
-
-    /*
-     * If gdb single-step, and we haven't raised another exception,
-     * raise a debug exception.  Single-step with another exception
-     * is handled in cpu_handle_exception.
-     */
-    if (unlikely(cpu_single_stepping(cpu)) && cpu->exception_index == -1) {
-        cpu->exception_index = EXCP_DEBUG;
-        cpu_loop_exit(cpu);
+    } else {
+        /*
+         * If gdb single-step, and we haven't raised another exception,
+         * raise a debug exception.  Single-step with another exception
+         * is handled in cpu_handle_exception.
+         */
+        if (unlikely(cpu_single_stepping(cpu)) && cpu->exception_index == -1) {
+            cpu->exception_index = EXCP_DEBUG;
+            cpu_loop_exit(cpu);
+        }
     }

     return last_tb;