Re: [Xen-devel] [PATCH v2 1/2] x86/AMD: correct certain Fam17 checks

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 05/04/2019 15:26, Jan Beulich wrote:
> Commit 3157bb4e13 ("Add MSR support for various feature AMD processor
> families") converted certain checks for Fam11 to include families all
> the way up to Fam17. The commit having no description, it is hard to
> tell whether this was a mechanical dec->hex conversion mistake, or
> indeed intended. In any event the NB_CFG handling needs to be restricted
> to Fam16 and below: Fam17 doesn't really have such an MSR anymore. As
> per observation it's read-zero / write-discard now, so make PV uniformly
> (with the exception of pinned Dom0 vCPU-s) behave so, just like HVM
> already does.
>
> Mirror the NB_CFG behavior to MSR_FAM10H_MMIO_CONF_BASE as well, except
> that here the vendor/model check is kept in place (for now at least).
>
> A non-MMCFG extended config space access mechanism still appears to
> exist, but code to deal with it will need to be written down the road,
> when it can actually be tested.
>
> Reported-by: Pu Wen <puwen@hygon.cn>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> v2: Make NB_CFG read-zero / write-discard for PV DomU, just like HVM has
>     it already. I've not applied "In principle, Acked-by: Andrew Cooper
>     <andrew.cooper3@citrix.com>".

I suppose this is slightly better intermediate step.  I guess I'll have
to do the proper fix of removing MSR_AMD64_NB_CFG from the guest
emulation paths, where it absolutely doesn't belong.

Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

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