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[3/3] accel/tcg: Implement cpu_exec_reset_hold() on user emulation

Message ID 20250102182521.65428-4-philmd@linaro.org
State New
Headers show
Series linux-user: Call tcg_flush_jmp_cache() before re-using threads | expand

Commit Message

Philippe Mathieu-Daudé Jan. 2, 2025, 6:25 p.m. UTC 
Commit bb6cf6f0168 ("accel/tcg: Factor tcg_cpu_reset_hold()
out") wanted to restrict tlb_flush() to system emulation,
but inadvertently also restricted tcg_flush_jmp_cache(),
which was before called on user emulation via:

  Realize -> Reset -> cpu_common_reset_hold()

Since threads (vCPUs) use a common CPUJumpCache, when many
threads are created / joined, they eventually end re-using
a CPUJumpCache entry, which was cleared when the first vCPU
was allocated (via Realize) but then stayed dirty, leading to:

  Thread 1 "qemu-s390x" received signal SIGABRT, Aborted.
  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at ./nptl/pthread_kill.c:44
  44      ./nptl/pthread_kill.c: No such file or directory.
  (gdb) bt
  #0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at ./nptl/pthread_kill.c:44
  #1  0x00007ffff7c41e8f in __pthread_kill_internal (signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:78
  #2  0x00007ffff7bf2fb2 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
  #3  0x00007ffff7bdd472 in __GI_abort () at ./stdlib/abort.c:79
  #4  0x00007ffff7bdd395 in __assert_fail_base (fmt=0x7ffff7d51a90 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x5555556d71b8 "cpu->accel",
      file=file@entry=0x5555556d70e0 "cpu-target.c", line=line@entry=158, function=function@entry=0x5555556d7260 <__PRETTY_FUNCTION__.3> "cpu_exec_realizefn") at ./assert/assert.c:92
  #5  0x00007ffff7bebeb2 in __GI___assert_fail (assertion=assertion@entry=0x5555556d71b8 "cpu->accel", file=file@entry=0x5555556d70e0 "cpu-target.c", line=line@entry=158,
      function=function@entry=0x5555556d7260 <__PRETTY_FUNCTION__.3> "cpu_exec_realizefn") at ./assert/assert.c:101
  #6  0x00005555555d44ca in cpu_exec_realizefn (cpu=cpu@entry=0x5555557c28c0, errp=errp@entry=0x7fffffffe140) at cpu-target.c:158
  #7  0x000055555559f50b in s390_cpu_realizefn (dev=0x5555557c28c0, errp=0x7fffffffe1a0) at target/s390x/cpu.c:261
  #8  0x000055555563f78b in device_set_realized (obj=<optimized out>, value=<optimized out>, errp=0x7fffffffe2e0) at hw/core/qdev.c:510
  #9  0x000055555564365d in property_set_bool (obj=0x5555557c28c0, v=<optimized out>, name=<optimized out>, opaque=0x5555557a9140, errp=0x7fffffffe2e0) at qom/object.c:2362
  #10 0x0000555555646bbb in object_property_set (obj=obj@entry=0x5555557c28c0, name=name@entry=0x5555556e8ae2 "realized", v=v@entry=0x5555557c6650, errp=errp@entry=0x7fffffffe2e0)
      at qom/object.c:1471
  #11 0x000055555564a45f in object_property_set_qobject (obj=obj@entry=0x5555557c28c0, name=name@entry=0x5555556e8ae2 "realized", value=value@entry=0x5555557a7a90, errp=errp@entry=0x7fffffffe2e0)
      at qom/qom-qobject.c:28
  #12 0x0000555555647224 in object_property_set_bool (obj=0x5555557c28c0, name=name@entry=0x5555556e8ae2 "realized", value=value@entry=true, errp=errp@entry=0x7fffffffe2e0)
      at qom/object.c:1541
  #13 0x000055555564027c in qdev_realize (dev=<optimized out>, bus=bus@entry=0x0, errp=errp@entry=0x7fffffffe2e0) at hw/core/qdev.c:291
  #14 0x000055555559bb54 in cpu_create (typename=<optimized out>) at hw/core/cpu-common.c:57
  #15 0x000055555559a467 in main (argc=4, argv=0x7fffffffeaa8, envp=<optimized out>) at linux-user/main.c:811

Have cpu_exec_reset_hold() call the common tcg_exec_reset()
helper on user emulation, eventually calling tcg_flush_jmp_cache().

Fixes: bb6cf6f0168 ("accel/tcg: Factor tcg_cpu_reset_hold() out")
Reported-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 accel/tcg/user-exec-stub.c | 4 ----
 accel/tcg/user-exec.c      | 5 +++++
 2 files changed, 5 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/accel/tcg/user-exec-stub.c b/accel/tcg/user-exec-stub.c
index 4fbe2dbdc88..2dc6fd9c4e8 100644
--- a/accel/tcg/user-exec-stub.c
+++ b/accel/tcg/user-exec-stub.c
@@ -14,10 +14,6 @@  void qemu_init_vcpu(CPUState *cpu)
 {
 }
 
-void cpu_exec_reset_hold(CPUState *cpu)
-{
-}
-
 /* User mode emulation does not support record/replay yet.  */
 
 bool replay_exception(void)
diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 0561c4f6dc7..92640f07ed7 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -40,6 +40,11 @@  __thread uintptr_t helper_retaddr;
 
 //#define DEBUG_SIGNAL
 
+void cpu_exec_reset_hold(CPUState *cpu)
+{
+    tcg_exec_reset(cpu);
+}
+
 void cpu_interrupt(CPUState *cpu, int mask)
 {
     g_assert(bql_locked());