On Tue, Sep 26, 2023, Sean Christopherson wrote: > Masking fpstate->user_xfeatures is buggy for another reason: it's destructive if > userspace calls KVM_SET_CPUID multiple times. No real world userspace actually > calls KVM_SET_CPUID to "expand" features, but it's technically possible and KVM > is supposed to allow it. This particular bit is wrong, KVM overwrites user_xfeatures, it doesn't AND it. I misremembered the code.
