Re: Patch "KVM: VMX: Convert vcpu_vmx.exit_reason to a union" has been added to the 5.10-stable tree

[Sean Christopherson <seanjc@google.com>]

On Mon, Apr 19, 2021, Sasha Levin wrote:
> On Mon, Apr 19, 2021 at 09:54:18PM +0000, Sean Christopherson wrote:
> > Maybe we'll end up with a more painful conflict in the future that would be best
> > solved by grabbing this refactoring, but I don't think we're there yet.
> 
> This is the tricky part: when we start having these conflicts it's
> usually too late to refactor, no one cares, and backports just don't
> happen.
> 
> I'd actually point to the file shuffling (commits like a821bab2d1ee
> ("KVM: VMX: Move VMX specific files to a "vmx" subdirectory")) you did a
> few years ago in arch/x86/kvm/ as an example to why we can't wait: those
> changes made a lot of sense upstream, but for stable kernels it meant
> that patches were now trying to touch the wrong files and would often
> fail or do the wrong thing.
> 
> On hindsight, we probably should have moved files around in stable trees
> as well to match what upstream had, but at this point it's too late to
> go back and fix that, and we're stuck manually editing paths for the
> lifetime of most of the LTS trees.

And I guess there's also the argument that inducing even a handful of manual
backports is more risky overall than taking this one "unnecessary" patch.

Objection withdrawn, I don't have a strong opinion either way :-)