On Thu, Feb 01, 2018 at 10:59:46PM +0100, KarimAllah Ahmed wrote: > [ Based on a patch from Paolo Bonzini <pbonzini@xxxxxxxxxx> ] > > ... basically doing exactly what we do for VMX: > > - Passthrough SPEC_CTRL to guests (if enabled in guest CPUID) > - Save and restore SPEC_CTRL around VMExit and VMEntry only if the guest > actually used it. > > Cc: Asit Mallick <asit.k.mallick@xxxxxxxxx> > Cc: Arjan Van De Ven <arjan.van.de.ven@xxxxxxxxx> > Cc: Dave Hansen <dave.hansen@xxxxxxxxx> > Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx> > Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> > Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: Andy Lutomirski <luto@xxxxxxxxxx> > Cc: Ashok Raj <ashok.raj@xxxxxxxxx> > Signed-off-by: KarimAllah Ahmed <karahmed@xxxxxxxxx> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > + { .index = MSR_IA32_SPEC_CTRL, .always = false }, This .always = [false|true] field keeps throwing me off. So glad: https://www.spinics.net/lists/kvm/msg161606.html explains it better.