Re: [EXTERNAL] Re: [PATCH 5/9] x86/hyperv: Use vmmcall to implement Hyper-V hypercall in sev-snp enlightened guest

Peter Zijlstra
2023-06-28T10:54:17Z

On Tue, Jun 27, 2023 at 03:38:35PM +0200, Peter Zijlstra wrote:

> That said; there is a tiny difference between:
>
> ALTERNATIVE_2(oldinst, newinst1, flag1, newinst2, flag2)
>
> and
>
> ALTERNATIVE(ALTERNATIVE(oldinst, newinst1, flag1),
> newinst2, flag2)
>
> and that is alt_instr::instrlen, when the inner alternative is the
> smaller, then the outer alternative will add additional padding that the
> inner (obviously) doesn't know about.