Re: [PATCH v8 02/14] KVM: Declare kvm_arch_flush_remote_tlbs() globally

[Shaoqin Huang]

On 8/10/23 00:38, Raghavendra Rao Ananta wrote:
> Hi Gavin,
>
> On Tue, Aug 8, 2023 at 9:00 PM Gavin Shan <gshan@xxxxxxxxxx> wrote:
> > On 8/9/23 09:13, Raghavendra Rao Ananta wrote:
> > > There's no reason for the architectures to declare
> > > kvm_arch_flush_remote_tlbs() in their own headers. Hence to
> > > avoid this duplication, make the declaration global, leaving
> > > the architectures to define only __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS
> > > as needed.
> > >
> > > Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> > > ---
> > >    arch/mips/include/asm/kvm_host.h | 1 -
> > >    include/linux/kvm_host.h         | 2 ++
> > >    2 files changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
> > > index 9b0ad8f3bf327..54a85f1d4f2c8 100644
> > > --- a/arch/mips/include/asm/kvm_host.h
> > > +++ b/arch/mips/include/asm/kvm_host.h
> > > @@ -897,6 +897,5 @@ static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {}
> > >    static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}
> > >
> > >    #define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS
> > > -int kvm_arch_flush_remote_tlbs(struct kvm *kvm);
> > >
> > >    #endif /* __MIPS_KVM_HOST_H__ */
> > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > > index e3f968b38ae97..ade5d4500c2ce 100644
> > > --- a/include/linux/kvm_host.h
> > > +++ b/include/linux/kvm_host.h
> > > @@ -1484,6 +1484,8 @@ static inline int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
> > >    {
> > >        return -ENOTSUPP;
> > >    }
> > > +#else
> > > +int kvm_arch_flush_remote_tlbs(struct kvm *kvm);
> > >    #endif
> > >
> > >    #ifdef __KVM_HAVE_ARCH_NONCOHERENT_DMA
> >
> > Is the declaration inconsistent to that in arch/x86/include/asm/kvm_host.h?
> > In order to keep them consistent, I guess we need move kvm_arch_flush_remote_tlbs()
> > from x86's header file to arch/x86/kvm/mmu/mmu.c and 'inline' needs to be dropped.
> Unsure of the original intentions, I didn't want to disturb any
> existing arrangements. If more people agree to this refactoring, I'm
> happy to move.

This is amazing to me. This change can be compiled without any error 
even if the declaration inconsistent between the kvm_host.h and x86's 
header file.

I'm curious which option make it possible?

Thanks,
Shaoqin

> Thank you.
> Raghavendra
> > Thanks,
> > Gavin

--
Shaoqin