Re: [PATCH 25/35] x86/cet/shstk: Add user-mode shadow stack support

[Andy Lutomirski]

On Fri, Feb 11, 2022, at 3:37 PM, Dave Hansen wrote:
> On 1/30/22 13:18, Rick Edgecombe wrote:
>> Add the user shadow stack MSRs to the xsave helpers, so they can be used
>> to implement the functionality.
>
> Do these MSRs ever affect kernel-mode operation?
>
> If so, we might need to switch them more aggressively at context-switch
> time like PKRU.
>
> If not, they can continue to be context-switched with the PASID state
> which does not affect kernel-mode operation.

PASID?  PASID is all kinds of weird.  I assume you mean switching it with all the normal state.

>
> Either way, it would be nice to have some changelog material to that effect.