On Mon, 21 Jul 2025 13:32:08 +0100, Cornelia Huck <cohuck@xxxxxxxxxx> wrote: > > On Mon, Jul 21 2025, Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > If we have RASv1p1 on the host, advertise it to the guest in the > > "canonical way", by setting ID_AA64PFR0_EL1 to V1P1, rather than > > the convoluted RAS+RAS_frac method. > > Don't the two methods have slightly different semantics with RAS == V1P1 > possibly implying FEAT_DoubleFault, and RAS+RAS_frac not? Ah, that's an interesting point -- I definitely had glanced over that. But I'm not sure a guest can actually distinguish between these two configurations, given that FEAT_DoubleFault is essentially an EL3 feature (as indicated in the RAS == V1P1 section, and further confirmed in R_GRJVN), making it invisible to the guest. FEAT_DoubleFault2 is, on the contrary, totally visible from the guest, and independent of EL3. Does this make sense to you? Thanks, M. -- Without deviation from the norm, progress is not possible.
