Messages in this thread | | | Subject | Re: [RFC v2-fix-v2 1/1] x86: Introduce generic protected guest abstractionn | From | Tom Lendacky <> | Date | Fri, 4 Jun 2021 18:31:03 -0500 |
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On 6/4/21 5:15 PM, Borislav Petkov wrote: > On Fri, Jun 04, 2021 at 05:01:31PM -0500, Tom Lendacky wrote: >> The first is analogous to sme_active(), the second to sev_active() and the >> third to mem_encrypt_active(). Just my opinion, though... > > Yeah, or cc_has() where "cc" means "confidential computing". Or "coco"... > > Yeah, no good idea yet. > >> I don't think you want a WARN_ON_ONCE() here. The code will be written to >> work with either SEV or TDX, so we shouldn't warn on a check for a TDX >> supported feature when running on AMD (or vice-versa). > > That's an AMD-specific path so it would warn only when a flag is used > which is unknown/unused yet on AMD.
But the check can happen on Intel or AMD. We have lots of checks for sme_active() in common code that are executed on Intel today, but they just return false. It's the same principle, you don't want to WARN on those, just return false. E.g.:
/* some common code path */ if (cc_has(XYZ)) do_y();
If Intel has XYZ but AMD does not, you don't want to WARN, just return false.
Thanks, Tom
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