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References: <20170423223240.17917-1-aurelien@aurel32.net>
From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= <f4bug@amsat.org>
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Date: Sun, 23 Apr 2017 19:38:48 -0300
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Subject: Re: [Qemu-devel] [PATCH v2] s390x/misc_helper.c: wrap
 s390_virtio_hypercall in BQL
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To: Aurelien Jarno <aurelien@aurel32.net>, qemu-devel@nongnu.org
Cc: Alexander Graf <agraf@suse.de>, Richard Henderson <rth@twiddle.net>

Hi Aurelien!

Why don't lock inside s390_virtio_hypercall() directly round the diag500 
dispatch call?

regards,

Phil.

On 04/23/2017 07:32 PM, Aurelien Jarno wrote:
> s390_virtio_hypercall can trigger IO events and interrupts, most notably
> when using virtio-ccw devices.
>
> Reviewed-by: Alexander Graf <agraf@suse.de>
> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> ---
>  target/s390x/misc_helper.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/target/s390x/misc_helper.c b/target/s390x/misc_helper.c
> index 4946b56ab3..aec737d707 100644
> --- a/target/s390x/misc_helper.c
> +++ b/target/s390x/misc_helper.c
> @@ -307,7 +307,9 @@ void HELPER(diag)(CPUS390XState *env, uint32_t r1, uint32_t r3, uint32_t num)
>      switch (num) {
>      case 0x500:
>          /* KVM hypercall */
> +        qemu_mutex_lock_iothread();
>          r = s390_virtio_hypercall(env);
> +        qemu_mutex_unlock_iothread();
>          break;
>      case 0x44:
>          /* yield */
>