Messages in this thread | | | From | "Edgecombe, Rick P" <> | Subject | Re: [PATCH 25/35] x86/cet/shstk: Add user-mode shadow stack support | Date | Sat, 12 Feb 2022 00:12:09 +0000 |
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On Fri, 2022-02-11 at 15:37 -0800, 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. > > Either way, it would be nice to have some changelog material to that > effect.
The only special shadow stack thing the kernel does is WRUSS, which per the SDM only needs the CR4 bit set to work (unlike WRSS). So I think the lazy restore is ok.
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