On 2/11/22 16:07, Andy Lutomirski wrote:

On Fri, Feb 11, 2022, at 3:37 PM, Dave Hansen wrote:

quoted

On 1/30/22 13:18, Rick Edgecombe wrote:

quoted

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.

I was grouping PASID along with the CET MSRs because they're the only
supervisor state.  But, yeah, it's all XRSTOR'd at the same spot right
now, user or kernel.