Re: [PATCH 1/3] Revert "x86/msr: drop compatibility #GP handling in guest_{rd,wr}msr()"

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Roger Pau Monné writes ("Re: [PATCH 1/3] Revert "x86/msr: drop compatibility 
#GP handling in guest_{rd,wr}msr()""):
> On Wed, Mar 17, 2021 at 02:46:20PM +0000, Ian Jackson wrote:
> > Roger, can I get your opinion about the possible downside risks of
> > this patch ?
> 
> For patches 1 and 2 the risk is low I think. This is already the same
> handling that we do in pre-4.15, so it's unlikely to cause issues.
> >From a guests PoV they don't change the result of trying to access any
> of the modified MSRs, accessing them will still result in a #GP being
> injected to the guest.
> 
> The main risk for patch 3 would be that reporting 0 for
> MSR_RAPL_POWER_UNIT would result in some kind of issue on certain
> guests, or that it triggers the poking of other MSRs in the
> expectation that they would be available. I think those are quite
> unlikely, and the patch fixes a real issue with Solaris guests.

Thanks.  That is very helpful.

All three patches 

Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>

but subject to Jan's questions on patch 3 being resolved somehow.

Ian.