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? If the advantage is basically not splitting the migration pool, is that a concern for the affected Alder Lake/Gracemont/Raptor Lake processors?
Paolo
