Re: [PATCH v3 7/7] x86/kvm: use Enlightened VMCS when running on Hyper-V

[Radim KrÄmÃÅ]

2018-03-15 20:28+0100, Thomas Gleixner:
> On Thu, 15 Mar 2018, Radim KrÄmÃÅ wrote:
> > 2018-03-15 16:19+0100, Vitaly Kuznetsov:
> > > This works. But hell, this is a crude hack :-) Not sure if there's a
> > > cleaner way to find what needs to be patched without something like jump
> > > label table ...
> > 
> > Yeah, I can see us accidently patching parts of other instructions. :)
> > 
> > The target instruction address can be made into a C-accessible symbol
> > with the same trick that vmx_return uses -- add a .global containing the
> > address of a label (not sure if a more direct approach would work).
> > 
> > The evil in me likes it.  (The good is too lazy to add a decent patching
> > infrastructure for just one user.)
> 
> Can we just use jump labels please? There is agreement that 4.17 will have
> a dependency on a jump label capable compiler for x86.

Luckily, it turned out that the path is very cold and should use the
simple test-and-jump.