On Tue, Aug 13, 2024, Pratik R. Sampat wrote:
> On 8/9/2024 10:40 AM, Sean Christopherson wrote:
> > On Wed, Jul 10, 2024, Pratik R. Sampat wrote:
> >> @@ -98,7 +100,7 @@ static inline void sev_register_encrypted_memory(struct kvm_vm *vm,
> >> vm_ioctl(vm, KVM_MEMORY_ENCRYPT_REG_REGION, &range);
> >> }
> >>
> >> -static inline void snp_launch_update_data(struct kvm_vm *vm, vm_paddr_t gpa,
> >> +static inline int snp_launch_update_data(struct kvm_vm *vm, vm_paddr_t gpa,
> >> uint64_t size, uint8_t type)
> >> {
> >> struct kvm_sev_snp_launch_update update_data = {
> >> @@ -108,10 +110,10 @@ static inline void snp_launch_update_data(struct kvm_vm *vm, vm_paddr_t gpa,
> >> .type = type,
> >> };
> >>
> >> - vm_sev_ioctl(vm, KVM_SEV_SNP_LAUNCH_UPDATE, &update_data);
> >> + return __vm_sev_ioctl(vm, KVM_SEV_SNP_LAUNCH_UPDATE, &update_data);
> >
> > Don't introduce APIs and then immediately rewrite all of the users. If you want
> > to rework similar APIs, do the rework, then add the new APIs. Doing things in
> > this order adds a pile of pointless churn.
> >
> > But that's a moot point, because it's far easier to just add __snp_launch_update_data().
> > And if you look through other APIs in kvm_util.h, you'll see that the strong
> > preference is to let vm_ioctl(), or in this case vm_sev_ioctl(), do the heavy
> > lifting. Yeah, it requires copy+pasting marshalling parameters into the struct,
> > but that's relatively uninteresting code, _and_ piggybacking the "good" version
> > means you can't do things like pass in a garbage virtual address (because the
> > "good" version always guarantees a good virtual address).
>
> I am a little confused by this.
>
> Are you suggesting that I leave the original functions intact with using
> vm_sev_ioctl() and have an additional variant such as
> __snp_launch_update_data() which calls into __vm_sev_ioctl() to decouple
> the ioctl from the assert for negative asserts?
Yes, this one.
> Or, do you suggest that I alter vm_sev_ioctl() to handle both positive
> and negative asserts?
>
> Thanks!
> -Pratik
>
