Re: [PATCH] accel: Do not set CPUState::can_do_io in non-TCG accels

[Claudio Fontana <cfontana@suse.de>]

Hi Philippe,

took a quick look with 

grep -R can_do_io

and this seems to be in include/hw/core/cpu.h as well as cpu-common.c,

maybe there is more meat to address to fully solve this?

Before we had stuff for reset in cpu-common.c under a
if (tcg_enabled()) {
}

but now we have cpu_exec_reset_hold(),
should the implementation for tcg of cpu_exec_reset_hold() do that (and potentially other tcg-specific non-arch-specific cpu variables we might need)?

If can_do_io is TCG-specific, maybe the whole field existence / visibility can be conditioned on TCG actually being at least compiled-in?
This might help find problems of the field being used in the wrong context, by virtue of getting an error when compiling with --disable-tcg for example.

Ciao,

Claudio


On 11/29/23 21:50, Philippe Mathieu-Daudé wrote:
> 'can_do_io' is specific to TCG. Having it set in non-TCG
> code is confusing, so remove it from QTest / HVF / KVM.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>  accel/dummy-cpus.c        | 1 -
>  accel/hvf/hvf-accel-ops.c | 1 -
>  accel/kvm/kvm-accel-ops.c | 1 -
>  3 files changed, 3 deletions(-)
> 
> diff --git a/accel/dummy-cpus.c b/accel/dummy-cpus.c
> index b75c919ac3..1005ec6f56 100644
> --- a/accel/dummy-cpus.c
> +++ b/accel/dummy-cpus.c
> @@ -27,7 +27,6 @@ static void *dummy_cpu_thread_fn(void *arg)
>      qemu_mutex_lock_iothread();
>      qemu_thread_get_self(cpu->thread);
>      cpu->thread_id = qemu_get_thread_id();
> -    cpu->neg.can_do_io = true;
>      current_cpu = cpu;
>  
>  #ifndef _WIN32
> diff --git a/accel/hvf/hvf-accel-ops.c b/accel/hvf/hvf-accel-ops.c
> index abe7adf7ee..2bba54cf70 100644
> --- a/accel/hvf/hvf-accel-ops.c
> +++ b/accel/hvf/hvf-accel-ops.c
> @@ -428,7 +428,6 @@ static void *hvf_cpu_thread_fn(void *arg)
>      qemu_thread_get_self(cpu->thread);
>  
>      cpu->thread_id = qemu_get_thread_id();
> -    cpu->neg.can_do_io = true;
>      current_cpu = cpu;
>  
>      hvf_init_vcpu(cpu);
> diff --git a/accel/kvm/kvm-accel-ops.c b/accel/kvm/kvm-accel-ops.c
> index 6195150a0b..f273f415db 100644
> --- a/accel/kvm/kvm-accel-ops.c
> +++ b/accel/kvm/kvm-accel-ops.c
> @@ -36,7 +36,6 @@ static void *kvm_vcpu_thread_fn(void *arg)
>      qemu_mutex_lock_iothread();
>      qemu_thread_get_self(cpu->thread);
>      cpu->thread_id = qemu_get_thread_id();
> -    cpu->neg.can_do_io = true;
>      current_cpu = cpu;
>  
>      r = kvm_init_vcpu(cpu, &error_fatal);