Watchpoint processing code restores vCPU state twice:
in tb_check_watchpoint and in cpu_loop_exit_restore/cpu_restore_state.
Normally it does not affect anything, but in icount mode instruction
counter is incremented twice and becomes incorrect.
This patch eliminates unneeded CPU state restore.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 softmmu/physmem.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index f67ad29981..fd1b3b2088 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -938,18 +938,16 @@ void cpu_check_watchpoint(CPUState *cpu, vaddr addr, vaddr len,
                 cpu->watchpoint_hit = wp;
 
                 mmap_lock();
+                /* This call also restores vCPU state */
                 tb_check_watchpoint(cpu, ra);
                 if (wp->flags & BP_STOP_BEFORE_ACCESS) {
                     cpu->exception_index = EXCP_DEBUG;
                     mmap_unlock();
-                    cpu_loop_exit_restore(cpu, ra);
+                    cpu_loop_exit(cpu);
                 } else {
                     /* Force execution of one insn next time.  */
                     cpu->cflags_next_tb = 1 | curr_cflags(cpu);
                     mmap_unlock();
-                    if (ra) {
-                        cpu_restore_state(cpu, ra, true);
-                    }
                     cpu_loop_exit_noexc(cpu);
                 }
             }

On 10/28/21 4:48 AM, Pavel Dovgalyuk wrote:
> Watchpoint processing code restores vCPU state twice:
> in tb_check_watchpoint and in cpu_loop_exit_restore/cpu_restore_state.
> Normally it does not affect anything, but in icount mode instruction
> counter is incremented twice and becomes incorrect.
> This patch eliminates unneeded CPU state restore.
> 
> Signed-off-by: Pavel Dovgalyuk<Pavel.Dovgalyuk@ispras.ru>
> Reviewed-by: David Hildenbrand<david@redhat.com>
> ---
>   softmmu/physmem.c |    6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~