* 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. Dave > > Dr. David Alan Gilbert (1): > KVM: x86: Always enable legacy FP/SSE in allowed user XFEATURES > > Sean Christopherson (2): > KVM: x86: Reinstate kvm_vcpu_arch.guest_supported_xcr0 > KVM: x86: Inject #UD on emulated XSETBV if XSAVES isn't enabled > > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/cpuid.c | 11 ++++++++--- > arch/x86/kvm/emulate.c | 3 +++ > arch/x86/kvm/x86.c | 10 +++------- > 4 files changed, 15 insertions(+), 10 deletions(-) > > > base-commit: 372d07084593dc7a399bf9bee815711b1fb1bcf2 > -- > 2.37.1.595.g718a3a8f04-goog > -- Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK
