Re: [RFC PATCH v2 21/34] x86/msr: Utilize the alternatives mechanism to write MSR

[Jürgen Groß]

On 24.04.25 10:06, Xin Li wrote:
> On 4/23/2025 9:05 AM, Jürgen Groß wrote:
> > > It's not a major change, but when it is patched to use the immediate form MSR 
> > > write instruction, it's straightforwardly streamlined.
> >
> > It should be rather easy to switch the current wrmsr/rdmsr paravirt patching
> > locations to use the rdmsr/wrmsr instructions instead of doing a call to
> > native_*msr().
> >
> > The case of the new immediate form could be handled the same way.
>
> Actually, that is how we get this patch with the existing alternatives
> infrastructure.  And we took a step further to also remove the pv_ops
> MSR APIs...

And this is what I'm questioning. IMHO this approach is adding more
code by removing the pv_ops MSR_APIs just because "pv_ops is bad". And
I believe most refusal of pv_ops is based on no longer valid reasoning.

> It looks to me that you want to add a new facility to the alternatives
> infrastructure first?

Why would we need a new facility in the alternatives infrastructure?


Juergen

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