From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53432) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cxYqs-0002UI-7X for qemu-devel@nongnu.org; Mon, 10 Apr 2017 08:55:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cxYqr-00038g-15 for qemu-devel@nongnu.org; Mon, 10 Apr 2017 08:55:26 -0400 Received: from mail-wm0-x231.google.com ([2a00:1450:400c:c09::231]:35923) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cxYqq-00038P-R8 for qemu-devel@nongnu.org; Mon, 10 Apr 2017 08:55:24 -0400 Received: by mail-wm0-x231.google.com with SMTP id o81so38078211wmb.1 for ; Mon, 10 Apr 2017 05:55:24 -0700 (PDT) From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Mon, 10 Apr 2017 13:55:21 +0100 Message-Id: <20170410125524.21008-9-alex.bennee@linaro.org> In-Reply-To: <20170410125524.21008-1-alex.bennee@linaro.org> References: <20170410125524.21008-1-alex.bennee@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Qemu-devel] [PULL 08/11] cpus: introduce cpu_update_icount helper List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: peter.maydell@linaro.org Cc: qemu-devel@nongnu.org, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Paolo Bonzini , Peter Crosthwaite , Richard Henderson By holding off updates to timer_state.qemu_icount we can run into trouble when the non-vCPU thread needs to know the time. This helper ensures we atomically update timers_state.qemu_icount based on what has been currently executed. Signed-off-by: Alex Bennée diff --git a/cpus.c b/cpus.c index 0ecb0b87f0..a5125d7167 100644 --- a/cpus.c +++ b/cpus.c @@ -232,12 +232,31 @@ static int64_t cpu_get_icount_executed(CPUState *cpu) return cpu->icount_budget - (cpu->icount_decr.u16.low + cpu->icount_extra); } +/* + * Update the global shared timer_state.qemu_icount to take into + * account executed instructions. This is done by the TCG vCPU + * thread so the main-loop can see time has moved forward. + */ +void cpu_update_icount(CPUState *cpu) +{ + int64_t executed = cpu_get_icount_executed(cpu); + cpu->icount_budget -= executed; + +#ifdef CONFIG_ATOMIC64 + atomic_set__nocheck(&timers_state.qemu_icount, + atomic_read__nocheck(&timers_state.qemu_icount) + + executed); +#else /* FIXME: we need 64bit atomics to do this safely */ + timers_state.qemu_icount += executed; +#endif +} + int64_t cpu_get_icount_raw(void) { int64_t icount; CPUState *cpu = current_cpu; - icount = timers_state.qemu_icount; + icount = atomic_read(&timers_state.qemu_icount); if (cpu && cpu->running) { if (!cpu->can_do_io) { fprintf(stderr, "Bad icount read\n"); @@ -1220,7 +1239,7 @@ static void process_icount_data(CPUState *cpu) { if (use_icount) { /* Account for executed instructions */ - timers_state.qemu_icount += cpu_get_icount_executed(cpu); + cpu_update_icount(cpu); /* Reset the counters */ cpu->icount_decr.u16.low = 0; diff --git a/include/qemu/timer.h b/include/qemu/timer.h index e1742f2f3d..8a1eb74839 100644 --- a/include/qemu/timer.h +++ b/include/qemu/timer.h @@ -869,6 +869,7 @@ int64_t cpu_get_icount_raw(void); int64_t cpu_get_icount(void); int64_t cpu_get_clock(void); int64_t cpu_icount_to_ns(int64_t icount); +void cpu_update_icount(CPUState *cpu); /*******************************************/ /* host CPU ticks (if available) */ -- 2.11.0