On Wed, Aug 24, 2022, Dr. David Alan Gilbert wrote: > * Sean Christopherson (seanjc@xxxxxxxxxx) wrote: > > Patch 2 (from Dave) is the headliner and fixes a bug where KVM clear the > > FP+SSE bits in user_xfeatures when XSAVE is hidden from the guest and thus > > prevent userspace from saving/restoring FP+SSE state on XSAVE host. This > > most visibily manifests as a failed migration (KVM_GET_XSAVE succeeds on a > > non-XSAVE host and KVM_SET_XSAVE fails on an XSAVE host), but also causes > > KVM_GET_SAVE on XSAVE hosts to effectively corrupt guest FP+SSE state. > > > > Patch 1 fixes a mostly theoretical bug, and is also a prerequisite for > > patch 2. > > > > Patch 3 fixes a bug found by inspection when staring at all of this. KVM > > fails to check CR4.OSXSAVE when emulating XSETBV (the interception case > > gets away without the check because the intercept happens after hardware > > checks CR4). > > Thanks for pulling those together; the set of 3 passes my same (light) smoke test. Paolo, do you want to grab this series for 6.0?
