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Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handlin
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR |
Date: |
Wed, 14 Jun 2017 12:45:34 +0100 |
User-agent: |
mu4e 0.9.19; emacs 25.2.50.3 |
Paolo Bonzini <address@hidden> writes:
> On 14/06/2017 06:48, Richard Henderson wrote:
>>>
>>> Commit e75449a3 ("target/aarch64: optimize indirect branches") causes
>>> a regression by which aarch64 guests freeze under TCG with -smp > 1,
>>> even with `-accel accel=tcg,thread=single' (i.e. MTTCG disabled).
>>>
>>> I isolated the problem to the MSR handler. This patch forces an exit
>>> after the handler is executed, which fixes the regression.
>>
>> Why would that be? The cpu_get_tb_cpu_state within helper_lookup_tb_ptr
>> is supposed to read the new state that the msr handler would have
>> installed.
>
> Could some of these cause an interrupt, or some other change in the
> cpu_exec flow?
Well what I was observing was the secondary_start_kernel stalling and
leaving the main cpu spinning. The msr is actually:
local_irq_enable();
local_fiq_enable();
Which I assume would re-enable IRQs if they are ready to go. However I
guess if we sink into our cpu_idle without exiting the main loop we
never set any pending IRQs?
>
> Thanks,
>
> Paolo
--
Alex Bennée
- [Qemu-devel] [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!), (continued)
- [Qemu-devel] [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!), Alex Bennée, 2017/06/09
- Re: [Qemu-devel] [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!), Richard Henderson, 2017/06/09
- Re: [Qemu-devel] [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!), Alex Bennée, 2017/06/10
- Re: [Qemu-devel] [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!), Richard Henderson, 2017/06/10
- Re: [Qemu-devel] [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!), Emilio G. Cota, 2017/06/11
- Re: [Qemu-devel] [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!), Alex Bennée, 2017/06/12
- [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Emilio G. Cota, 2017/06/13
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, no-reply, 2017/06/13
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Richard Henderson, 2017/06/14
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Paolo Bonzini, 2017/06/14
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR,
Alex Bennée <=
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Paolo Bonzini, 2017/06/14
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Alex Bennée, 2017/06/14
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Paolo Bonzini, 2017/06/14
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Alex Bennée, 2017/06/14
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Paolo Bonzini, 2017/06/14
- Re: [Qemu-devel] [PATCH] target/aarch64: exit to main loop after handling MSR, Alex Bennée, 2017/06/14
Re: [Qemu-devel] [RFC DEBUG PATCH 0/3] debug patch for lookup-ptr hang, no-reply, 2017/06/09