Re: [PATCH v2 11/11] softmmu/vl: Exit gracefully when accelerator is not supported

[Cornelia Huck <cohuck@xxxxxxxxxx>]

On Fri, 19 Feb 2021 18:38:47 +0100
Philippe Mathieu-Daudé <philmd@xxxxxxxxxx> wrote:

> Before configuring an accelerator, check it is valid for
> the current machine. Doing so we can return a simple error
> message instead of criptic one.

s/criptic/cryptic/

> 
> Before:
> 
>   $ qemu-system-arm -M raspi2b -enable-kvm
>   qemu-system-arm: /build/qemu-ETIdrs/qemu-4.2/exec.c:865: 
> cpu_address_space_init: Assertion `asidx == 0 || !kvm_enabled()' failed.
>   Aborted
> 
>   $ qemu-system-aarch64 -M xlnx-zcu102 -enable-kvm -smp 6
>   qemu-system-aarch64: kvm_init_vcpu: kvm_arch_init_vcpu failed (0): Invalid 
> argument
> 
> After:
> 
>   $ qemu-system-arm -M raspi2b -enable-kvm
>   qemu-system-aarch64: invalid accelerator 'kvm' for machine raspi2b
> 
>   $ qemu-system-aarch64 -M xlnx-zcu102 -enable-kvm -smp 6
>   qemu-system-aarch64: -accel kvm: invalid accelerator 'kvm' for machine 
> xlnx-zcu102
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
> ---
>  softmmu/vl.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index b219ce1f357..f2c4074310b 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -2133,6 +2133,7 @@ static int do_configure_accelerator(void *opaque, 
> QemuOpts *opts, Error **errp)
>      const char *acc = qemu_opt_get(opts, "accel");
>      AccelClass *ac = accel_find(acc);
>      AccelState *accel;
> +    MachineClass *mc;
>      int ret;
>      bool qtest_with_kvm;
>  
> @@ -2145,6 +2146,12 @@ static int do_configure_accelerator(void *opaque, 
> QemuOpts *opts, Error **errp)
>          }
>          return 0;
>      }
> +    mc = MACHINE_GET_CLASS(current_machine);
> +    if (!qtest_chrdev && !machine_class_valid_for_accelerator(mc, ac->name)) 
> {

Shouldn't qtest be already allowed in any case in the checking function?

> +        *p_init_failed = true;
> +        error_report("invalid accelerator '%s' for machine %s", acc, 
> mc->name);
> +        return 0;
> +    }
>      accel = ACCEL(object_new_with_class(OBJECT_CLASS(ac)));
>      object_apply_compat_props(OBJECT(accel));
>      qemu_opt_foreach(opts, accelerator_set_property,