On Thursday, April 18, 2024 9:59 PM, Sean Christopherson wrote: > On Thu, Apr 18, 2024, Wei W Wang wrote: > > On Thursday, April 18, 2024 12:27 AM, Sean Christopherson wrote: > > > On Wed, Apr 17, 2024, Wei Wang wrote: > > > > Introduces two new macros, KVM_X86_SC() and KVM_X86_SCC(), to > > > > streamline the usage of KVM_X86_OPS static calls. The current > > > > implementation of these calls is verbose and can lead to alignment > > > > challenges due to the two pairs of parentheses. This makes the > > > > code susceptible to exceeding the "80 columns per single line of code" > > > > limit as defined in the coding-style document. The two macros are > > > > added to improve code readability and maintainability, while > > > > adhering to > > > the coding style guidelines. > > > > > > Heh, I've considered something similar on multiple occasionsi. Not > > > because the verbosity bothers me, but because I often search for > > > exact "word" matches when looking for function usage and the kvm_x86_ > prefix trips me up. > > > > Yeah, that's another compelling reason for the improvement. > > > > > IIRC, static_call_cond() is essentially dead code, i.e. it's the > > > exact same as static_call(). I believe there's details buried in a > > > proposed series to remove it[*]. And to not lead things astray, I > > > verified that invoking a NULL kvm_x86_op with static_call() does no harm > (well, doesn't explode at least). > > > > > > So if we add wrapper macros, I would be in favor in removing all > > > static_call_cond() as a prep patch so that we can have a single macro. > > > > Sounds good. Maybe KVM_X86_OP_OPTIONAL could now also be removed? > > No, KVM_X86_OP_OPTIONAL() is what allow KVM to WARN if a mandatory > hook isn't defined. Without the OPTIONAL and OPTIONAL_RET variants, KVM > would need to assume every hook is optional, and thus couldn't WARN. Yes, KVM_X86_OP_OPTIONAL is used to enforce the definition of mandatory hooks with WARN_ON(). But the distinction between mandatory and optional hooks has now become ambiguous. For example, all the hooks, whether defined or undefined (NULL), are invoked via static_call() without issues now. In some sense, all hooks could potentially be deemed as optional, and the undefined ones just lead to NOOP when unconditionally invoked by the kvm/x86 core code. (the KVM_X86_OP_RET0 is needed) Would you see any practical issues without that WARN_ON?
