From 0dfe952dc5c2921488a1172407857d5bb81d17a4 Mon Sep 17 00:00:00 2001 From: Roman Kapl Date: Mon, 9 Jan 2017 12:23:38 +0100 Subject: ppc: Prevent inifnite loop in decrementer auto-reload. If the DECAR register is set to 0, QEMU tries to reload the decrementer with zero in an inifinite loop. According to PPC documentation, the decrementer is triggered on 1->0 transition, so avoid reloading the decrementer if if is already zero. The problem does not manifest under Linux, but it is valid to set DECAR to zero (and may make sense as part of decrementer initialization when interrupts are disabled). Signed-off-by: Roman Kapl [dwg: Fixed style nit] Signed-off-by: David Gibson --- hw/ppc/ppc_booke.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'hw/ppc') diff --git a/hw/ppc/ppc_booke.c b/hw/ppc/ppc_booke.c index ab8d026c32..60baffaf1d 100644 --- a/hw/ppc/ppc_booke.c +++ b/hw/ppc/ppc_booke.c @@ -198,8 +198,12 @@ static void booke_decr_cb(void *opaque) booke_update_irq(cpu); if (env->spr[SPR_BOOKE_TCR] & TCR_ARE) { - /* Auto Reload */ - cpu_ppc_store_decr(env, env->spr[SPR_BOOKE_DECAR]); + /* Do not reload 0, it is already there. It would just trigger + * the timer again and lead to infinite loop */ + if (env->spr[SPR_BOOKE_DECAR] != 0) { + /* Auto Reload */ + cpu_ppc_store_decr(env, env->spr[SPR_BOOKE_DECAR]); + } } } -- cgit v1.2.3