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[PULL 01/39] accel/tcg: mttcg remove false-negative halted assertion
From: |
Richard Henderson |
Subject: |
[PULL 01/39] accel/tcg: mttcg remove false-negative halted assertion |
Date: |
Fri, 15 Sep 2023 20:29:33 -0700 |
From: Nicholas Piggin <npiggin@gmail.com>
mttcg asserts that an execution ending with EXCP_HALTED must have
cpu->halted. However between the event or instruction that sets
cpu->halted and requests exit and the assertion here, an
asynchronous event could clear cpu->halted.
This leads to crashes running AIX on ppc/pseries because it uses
H_CEDE/H_PROD hcalls, where H_CEDE sets self->halted = 1 and
H_PROD sets other cpu->halted = 0 and kicks it.
H_PROD could be turned into an interrupt to wake, but several other
places in ppc, sparc, and semihosting follow what looks like a similar
pattern setting halted = 0 directly. So remove this assertion.
Reported-by: Ivan Warren <ivan@vmfacility.fr>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20230829010658.8252-1-npiggin@gmail.com>
[rth: Keep the case label and adjust the comment.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
accel/tcg/tcg-accel-ops-mttcg.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/accel/tcg/tcg-accel-ops-mttcg.c b/accel/tcg/tcg-accel-ops-mttcg.c
index b276262007..4b0dfb4be7 100644
--- a/accel/tcg/tcg-accel-ops-mttcg.c
+++ b/accel/tcg/tcg-accel-ops-mttcg.c
@@ -100,14 +100,9 @@ static void *mttcg_cpu_thread_fn(void *arg)
break;
case EXCP_HALTED:
/*
- * during start-up the vCPU is reset and the thread is
- * kicked several times. If we don't ensure we go back
- * to sleep in the halted state we won't cleanly
- * start-up when the vCPU is enabled.
- *
- * cpu->halted should ensure we sleep in wait_io_event
+ * Usually cpu->halted is set, but may have already been
+ * reset by another thread by the time we arrive here.
*/
- g_assert(cpu->halted);
break;
case EXCP_ATOMIC:
qemu_mutex_unlock_iothread();
--
2.34.1
- [PULL 00/39] tcg patch queue, Richard Henderson, 2023/09/15
- [PULL 01/39] accel/tcg: mttcg remove false-negative halted assertion,
Richard Henderson <=
[PULL 02/39] accel/tcg: Fix the comment for CPUTLBEntryFull, Richard Henderson, 2023/09/15
[PULL 03/39] util: Delete checks for old host definitions, Richard Henderson, 2023/09/15
[PULL 05/39] thunk: Delete checks for old host definitions, Richard Henderson, 2023/09/15
[PULL 04/39] softmmu: Delete checks for old host definitions, Richard Henderson, 2023/09/15
[PULL 07/39] tcg/loongarch64: Lower basic tcg vec ops to LSX, Richard Henderson, 2023/09/15
[PULL 08/39] tcg: pass vece to tcg_target_const_match(), Richard Henderson, 2023/09/15