Re: [PATCH 6/8] hvf: Use OS provided vcpu kick function

From: Eduardo Habkost <ehabkost@redhat.com>
To: Alexander Graf <agraf@csgraf.de>
Cc: Peter Maydell <peter.maydell@linaro.org>,
	Richard Henderson <richard.henderson@linaro.org>,
	qemu-devel@nongnu.org, Cameron Esfahani <dirty@apple.com>,
	Roman Bolshakov <r.bolshakov@yadro.com>,
	qemu-arm@nongnu.org, Claudio Fontana <cfontana@suse.de>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 6/8] hvf: Use OS provided vcpu kick function
Date: Thu, 26 Nov 2020 17:18:08 -0500	[thread overview]
Message-ID: <20201126221808.GU2271382@habkost.net> (raw)
In-Reply-To: <20201126215017.41156-7-agraf@csgraf.de>

On Thu, Nov 26, 2020 at 10:50:15PM +0100, Alexander Graf wrote:
> When kicking another vCPU, we get an OS function that explicitly does that for us
> on Apple Silicon. That works better than the current signaling logic, let's make
> use of it there.
> 
> Signed-off-by: Alexander Graf <agraf@csgraf.de>
> ---
>  accel/hvf/hvf-cpus.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/accel/hvf/hvf-cpus.c b/accel/hvf/hvf-cpus.c
> index b9f674478d..74a272d2e8 100644
> --- a/accel/hvf/hvf-cpus.c
> +++ b/accel/hvf/hvf-cpus.c
> @@ -418,8 +418,20 @@ static void hvf_start_vcpu_thread(CPUState *cpu)
>                         cpu, QEMU_THREAD_JOINABLE);
>  }
>  
> +#ifdef __aarch64__
> +static void hvf_kick_vcpu_thread(CPUState *cpu)
> +{
> +    if (!qemu_cpu_is_self(cpu)) {
> +        hv_vcpus_exit(&cpu->hvf_fd, 1);
> +    }
> +}
> +#endif
> +
>  static const CpusAccel hvf_cpus = {
>      .create_vcpu_thread = hvf_start_vcpu_thread,
> +#ifdef __aarch64__
> +    .kick_vcpu_thread = hvf_kick_vcpu_thread,
> +#endif

Interesting.  We have considered the possibility of adding
arch-specific TYPE_ACCEL subclasses when discussing Claudio's,
series.  Here we have another arch-specific hack that could be
avoided if we had a TYPE_ARM_HVF_ACCEL QOM class.

>  
>      .synchronize_post_reset = hvf_cpu_synchronize_post_reset,
>      .synchronize_post_init = hvf_cpu_synchronize_post_init,
> -- 
> 2.24.3 (Apple Git-128)
> 

-- 
Eduardo