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

Shaoqin Huang
2023-08-10T12:27:13Z

On 8/10/23 00:38, Raghavendra Rao Ananta wrote:
> Hi Gavin,
>
> On Tue, Aug 8, 2023 at 9:00 PM Gavin Shan <gshan@redhat.com> 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@google.com>
>>> ---
>>> 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