Re: [PATCH v2 04/22] x86/kvm: Don't call kvm_spurious_fault() from .fixup

[Josh Poimboeuf]

On Thu, Jul 18, 2019 at 03:18:50PM +0200, Paolo Bonzini wrote:
> On 18/07/19 15:16, Sean Christopherson wrote:
> >> Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> >>
> >> This has a side effect of adding a jump in a generally hot path, but
> >> let's hope that the speculation gods for once help us.
> > Any reason not to take the same approach as vmx_vmenter() and ud2 directly
> > from fixup?  I've never found kvm_spurious_fault() to be all that helpful,
> > IMO it's a win win. :-)
> 
> Honestly I've never seen a backtrace from here but I would rather not
> regret this when a customer encounters it...

In theory, changing the "call kvm_spurious_fault" to ud2 should be fine.
It should be tested, of course.

I would defer to Sean to make the patch on top of mine :-)

-- 
Josh