Re: [PATCH for-4.15 v1.1 1/3] Revert "x86/msr: drop compatibility #GP handling in guest_{rd,wr}msr()"

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Jan Beulich writes ("[PATCH for-4.15 v1.1 1/3] Revert "x86/msr: drop 
compatibility #GP handling in guest_{rd,wr}msr()""):
> From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
> In hindsight, this was a poor move.  Some of these MSRs require probing for,
> cause unhelpful spew into xl dmesg, or cause spew from unit tests explicitly
> checking behaviour.
> 
> This restores behaviour close to that of Xen 4.14, meaning in particular
> that for all of the MSRs getting re-added explicitly a #GP fault will get
> raised irrespective of the new "msr_relaxed" setting.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>
> ---
> v1.1: Fold in suggested description adjustments.
> ---
> For 4.15.  Restoring behaviour closer to 4.14, and prereq for a bugfix needing
> backporting.

Thank you, and thanks for the helpful irc discussion.

Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>

I will commit this shortly.

For the record, we concluded on irc that we weren't sure that 2/ and
3/ of this series were right, so we are not going to include them in
4.15, pending further consideration/investigation.

Ian.