On Thu, Apr 11, 2024, Paolo Bonzini wrote: > On 4/11/24 18:31, Sean Christopherson wrote: > > Force set a synthetic feature, GUEST_PCID, if PCID can be safely used in > > virtual machines, even if the kernel itself disables PCID support, and > > advertise PCID support in KVM if GUEST_PCID is set. > > > > When running on a CPU that is affected by Intel's "Global INVLPG" erratum, > > which does NOT affect VMX non-root mode, it is safe to virtualize PCID for > > KVM guests, even though it is not safe for the kernel itself to enable PCID. > > Ditto for if the kernel disables PCID because CR4.PGE isn't supported. > > But the guest would not use it if the f/m/s matches, right? Maybe? There's another in-flight patch for dealing with the guest side of things. https://lore.kernel.org/all/20240411144322.14585-2-xry111@xxxxxxxxxxx > If the advantage is basically not splitting the migration pool, is that a > concern for the affected Alder Lake/Gracemont/Raptor Lake processors? I have put _zero_ thought into what value this actually adds (another reason I tagged it RFC). This was purely a "it's easy, so why not".
