cpu_interrupt() is only called by a few user-mode emulation targets:
i386, ppc, sparc, arm. For all of them it is dead code:
- i386 uses it for the A20 line
- ppc uses it in cpu_interrupt_exittb(), whose uses (but not the definition)
are guarded by CONFIG_USER_ONLY
- likewise for sparc's cpu_check_irqs()
Arm has various uses in arm_cpu_update_v* and omap_wfi_write, but they are
also dead; disentangling the various cpregs accessors from user-mode
emulation is a work in progress.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
A quick and dirty patch that I'd like to place before Igor's
https://patchew.org/QEMU/20250814160600.2327672-1-imammedo@redhat.com/,
to document that interrupt_request is dead for user-mode emulation.
v2 of https://patchew.org/QEMU/20250808185905.62776-1-pbonzini@redhat.com/
will also remove callers of cpu_interrupt() treewide.
include/hw/core/cpu.h | 1 +
accel/tcg/cpu-exec.c | 6 ++++--
accel/tcg/user-exec.c | 4 +---
3 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 5eaf41a566f..f73b4357c7b 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -423,6 +423,7 @@ struct qemu_work_item;
* @created: Indicates whether the CPU thread has been successfully created.
* @halt_cond: condition variable sleeping threads can wait on.
* @interrupt_request: Indicates a pending interrupt request.
+ * Only used by system emulation.
* @halted: Nonzero if the CPU is in suspended state.
* @stop: Indicates a pending stop request.
* @stopped: Indicates the CPU has been artificially stopped.
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 713bdb20564..b44dd1e8205 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -778,6 +778,9 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
*/
qatomic_set_mb(&cpu->neg.icount_decr.u16.high, 0);
+#ifdef CONFIG_USER_ONLY
+ g_assert(!qatomic_read(&cpu->interrupt_request));
+#else
if (unlikely(qatomic_read(&cpu->interrupt_request))) {
int interrupt_request;
bql_lock();
@@ -792,7 +795,6 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
bql_unlock();
return true;
}
-#if !defined(CONFIG_USER_ONLY)
if (replay_mode == REPLAY_MODE_PLAY && !replay_has_interrupt()) {
/* Do nothing */
} else if (interrupt_request & CPU_INTERRUPT_HALT) {
@@ -840,7 +842,6 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
* reload the 'interrupt_request' value */
interrupt_request = cpu->interrupt_request;
}
-#endif /* !CONFIG_USER_ONLY */
if (interrupt_request & CPU_INTERRUPT_EXITTB) {
cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
/* ensure that no TB jump will be modified as
@@ -851,6 +852,7 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
/* If we exit via cpu_loop_exit/longjmp it is reset in cpu_exec */
bql_unlock();
}
+#endif /* !CONFIG_USER_ONLY */
/* Finally, check if we need to exit to the main loop. */
if (unlikely(qatomic_read(&cpu->exit_request)) || icount_exit_request(cpu)) {
diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index f25d80e2dc2..748bfab04a7 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -48,9 +48,7 @@ __thread uintptr_t helper_retaddr;
void cpu_interrupt(CPUState *cpu, int mask)
{
- g_assert(bql_locked());
- cpu->interrupt_request |= mask;
- qatomic_set(&cpu->neg.icount_decr.u16.high, -1);
+ g_assert_not_reached();
}
/*
--
2.51.0