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References: <20170330164657.50c75e8c@nial.brq.redhat.com>
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From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
In-reply-to: <20170331102125.52405cd2@nial.brq.redhat.com>
Date: Fri, 31 Mar 2017 09:58:49 +0100
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Subject: Re: [Qemu-devel] qemu-2.9 crashes in tcg_handle_interrupt() during
 winx64 boot
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To: Igor Mammedov <imammedo@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel@nongnu.org, "Emilio G. Cota" <cota@braap.org>, Paolo Bonzini <pbonzini@redhat.com>, Pranith Kumar <bobby.prani@gmail.com>, KONRAD Frederic <fred.konrad@greensocs.com>, Richard Henderson <rth@twiddle.net>


Igor Mammedov <imammedo@redhat.com> writes:

> On Thu, 30 Mar 2017 16:05:58 +0100
> Alex Bennée <alex.bennee@linaro.org> wrote:
>
>> Igor Mammedov <imammedo@redhat.com> writes:
>>
>> > (PS: resend due to wrong qemu-devel mail list address in original
>> > email)
>>
>> Le *sigh* another way of x86 generating IRQs ;-)
>>
>> Could you test this please?
>>
>> target/i386/misc_helper: wrap BQL around another IRQ generator
>>
>> Anything that calls into HW emulation must be protected by the BQL.
>>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> it doesn't help,
> it asserts in the same place anyway

That's weird. If the lock was already held I could see it failing higher
up but this seems to imply we are dropping a lock as we descend into
hardware emulation.

How often does this leg of the helper get called?

>
>>
>> 1 file changed, 2 insertions(+)
>> target/i386/misc_helper.c | 2 ++
>>
>> modified   target/i386/misc_helper.c
>> @@ -156,7 +156,9 @@ void helper_write_crN(CPUX86State *env, int reg, target_ulong t0)
>>          break;
>>      case 8:
>>          if (!(env->hflags2 & HF2_VINTR_MASK)) {
>> +            qemu_mutex_lock_iothread();
>>              cpu_set_apic_tpr(x86_env_get_cpu(env)->apic_state, t0);
>> +            qemu_mutex_unlock_iothread();
>>          }
>>          env->v_tpr = t0 & 0x0f;
>>          break;
>> --
>> Alex Bennée
>>


--
Alex Bennée