Re: [Qemu-devel] [PATCH RFC 5/7] s390x/pci: fence off instructions for non-pci

[Thomas Huth]

On 07.07.2017 14:21, Cornelia Huck wrote:
> If a guest running on a non-pci build issues a pci instruction,
> throw them an exception.
> 
> Signed-off-by: Cornelia Huck <address@hidden>
> ---
>  target/s390x/kvm.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index a3d00196f4..c5c7c27a21 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -1160,6 +1160,9 @@ static int kvm_clp_service_call(S390CPU *cpu, struct 
> kvm_run *run)
>  {
>      uint8_t r2 = (run->s390_sieic.ipb & 0x000f0000) >> 16;
>  
> +#ifndef CONFIG_PCI
> +    return -1;
> +#endif
>      return clp_service_call(cpu, r2);
>  }
>  
> @@ -1168,6 +1171,9 @@ static int kvm_pcilg_service_call(S390CPU *cpu, struct 
> kvm_run *run)
>      uint8_t r1 = (run->s390_sieic.ipb & 0x00f00000) >> 20;
>      uint8_t r2 = (run->s390_sieic.ipb & 0x000f0000) >> 16;
>  
> +#ifndef CONFIG_PCI
> +    return -1;
> +#endif
>      return pcilg_service_call(cpu, r1, r2);
>  }

pcilg_service_call() seems to be defined in s390-pci-inst.c ... which
you later remove from the !CONFIG_PCI builds... so I wonder why this
still compiles ... I guess GCC is smart enough to optimize it away.
Anyway, to be on the safe side (and to be able to compile with -O0), you
should maybe rather do this instead:

#ifndef CONFIG_PCI
    return -1;
#else
    return pcilg_service_call(cpu, r1, r2);
#endif

?

 Thomas