Re: [PATCH] [fix] kernel does not compile without CONFIG_KVM_ARM_VGIC

[Christoffer Dall <christoffer.dall@linaro.org>]

On Thu, Mar 06, 2014 at 03:30:46AM +0000, Marc Zyngier wrote:
> Paolo, Michele,
> 
> On 2014-03-04 15:31, Paolo Bonzini wrote:
> >Il 04/03/2014 16:10, Michele Paolino ha scritto:
> >>When the kernel is configured without CONFIG_KVM_ARM_VGIC, the
> >>compilation process fails with :
> >>
> >>arch/arm/kvm/arm.c: In function 'kvm_vm_ioctl_set_device_addr':
> >>arch/arm/kvm/arm.c:797:3: error: implicit declaration of
> >>  function 'kvm_vgic_addr' [-Werror=implicit-function-declaration]
> >>   return kvm_vgic_addr(kvm, type, &dev_addr->addr, true)
> >>
> >>Signed-off-by: Michele Paolino <m.paolino@virtualopensystems.com>
> >>---
> >> include/kvm/arm_vgic.h |    2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >>diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> >>index be85127..0bab057 100644
> >>--- a/include/kvm/arm_vgic.h
> >>+++ b/include/kvm/arm_vgic.h
> >>@@ -143,8 +143,8 @@ struct kvm_vcpu;
> >> struct kvm_run;
> >> struct kvm_exit_mmio;
> >>
> >>-#ifdef CONFIG_KVM_ARM_VGIC
> >> int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64
> >>*addr, bool write);
> >>+#ifdef CONFIG_KVM_ARM_VGIC
> >> int kvm_vgic_hyp_init(void);
> >> int kvm_vgic_init(struct kvm *kvm);
> >> int kvm_vgic_create(struct kvm *kvm);
> >>
> >
> >Christoffer, Marc, I can queue this directly for kvm/master if
> >it's okay
> >for you.
> 
> This patch looks a bit wrong. Why would we need to configure the
> vgic addresses if the vgic is explicitly disabled?
> Furthermore, I doubt it leads to a kernel that actually links, as
> the file containing kvm_vgic_addr will not be compiled...
> 
> Instead, please consider applying the attached patch (quickly tested
> on a Cubietruck).
> 
> Thanks,
> 
>         M.
> -- 
> Fast, cheap, reliable. Pick two.

> From 0876a7f6851e011b24f61ccbada35a5e8b898dd2 Mon Sep 17 00:00:00 2001
> From: Marc Zyngier <marc.zyngier@arm.com>
> Date: Thu, 6 Mar 2014 03:21:36 +0000
> Subject: [PATCH] ARM: KVM: fix non-VGIC compilation
> 
> Add a stub for kvm_vgic_addr when compiling without
> CONFIG_KVM_ARM_VGIC. The usefulness of this configurarion is extremely
> doubtful, but let's fix it anyway (until we decide that we'll always
> support a VGIC).
> 
> Reported-by: Michele Paolino <m.paolino@virtualopensystems.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Christoffer Dall <christoffer.dall@linaro.org>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
>  include/kvm/arm_vgic.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index be85127..f27000f 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -171,6 +171,11 @@ static inline int kvm_vgic_set_addr(struct kvm *kvm, unsigned long type, u64 add
>  	return 0;
>  }
>  
> +static inline int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
> +{
> +	return -ENXIO;
> +}
> +
>  static inline int kvm_vgic_init(struct kvm *kvm)
>  {
>  	return 0;
> -- 
> 1.9.0
> 

This looks right to me.  I can queue this for the next -rc release.

Thanks,
-Christoffer