> >>>>> --- a/arch/arm/include/uapi/asm/kvm.h > >>>>> +++ b/arch/arm/include/uapi/asm/kvm.h > >>>>> @@ -124,6 +124,18 @@ struct kvm_sync_regs { struct > >>>>> kvm_arch_memory_slot { }; > >>>>> > >>>>> +/* for KVM_GET/SET_VCPU_EVENTS */ struct kvm_vcpu_events { > >>>>> + struct { > >>>>> + __u8 serror_pending; > >>>>> + __u8 serror_has_esr; > >>>>> + /* Align it to 8 bytes */ > >>>>> + __u8 pad[6]; > >>>>> + __u64 serror_esr; > >>>>> + } exception; > >>>>> + __u32 reserved[12]; > >>>>> +}; > >>>>> + > >>>> > >>>> You haven't defined __KVM_HAVE_VCPU_EVENTS for 32bit, so presumably > >>>> this struct will never be used. Why is it here? > >> > >>> if not add it for 32 bits. the 32 arm platform will build Fail, whether you have good > >>> idea to avoid this Failure if not add this struct for the 32 bit? > >> > >> How does this 32bit code build without this patch? > >> If do you provide the struct, how will that code build with older headers? > >> > >> As far as I can see, this is what the __KVM_HAVE_VCPU_EVENTS define is for. > >> > >> This should be both, or neither. Having just the struct is useless. > > It because the caller of kvm_arm_vcpu_get/set_events() is in "virt/kvm/arm/arm.c". > > the virt/kvm/arm/arm.c will used by both arm64 and arm. > > so It needs to add kvm_arm_vcpu_get/set_events() for the 32 bits, > > however, kvm_arm_vcpu_get/set_events() will directly return, > > So you are adding a uapi struct that user-space can't actually use, to avoid a kernel build-error. Fine, it just looks really strange. > > 32bit user-space shouldn't try to call this as check-extension reports it as not present. If it does, it gets -EINVAL back, which is also the > default for kvm_arch_vcpu_ioctl(). It indeed looks strange. Because "virt/kvm/arm/arm.c" is shared by arm64 and arm32, if not adding, it will build-error. Do you have a better idea to avoid adding in arm32? I still not think out a good method. 32 user-space will not call this KVM_GET/SET_VCPU_EVENTS IOCTL as check-extension reports it as not present. > > > Thanks, > > James ��.n��������+%������w��{.n�����{����*jg��������ݢj����G�������j:+v���w�m������w�������h�����٥