On Fri, Sep 21, 2018 at 10:59:36AM -0700, Jim Mattson wrote: > On Fri, Sep 21, 2018 at 10:57 AM, Sean Christopherson > <sean.j.christopherson@xxxxxxxxx> wrote: > > > Is there any chance that DR6_RTM could be cleared in arch.dr6 without > > HLE/RTM being exposed to the guest? I.e. should we explicitly clear > > DR6_RTM if !HLE && !RTM? > > That would be a bug. Section 17.2.3 of the SDM (volume 3) says: "This > bit is always 1 if the processor does not support RTM." My question was more from a software perspective, e.g. it looks like arch.dr6.RTM can be cleared via kvm_vcpu_ioctl_x86_set_debugregs() and a #DB injected via kvm_arch_vcpu_ioctl_set_guest_debug(). Not saying such behavior wouldn't be a bug elsewhere, just wondering if we should be paranoid here.
