On Fri, Jan 31, 2020 at 12:57:51PM -0800, Andy Lutomirski wrote: > > > On Jan 31, 2020, at 12:18 PM, Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote: > > > > This is essentially what I proposed a while back. KVM would allow enabling > > split-lock #AC in the guest if and only if SMT is disabled or the enable bit > > is per-thread, *or* the host is in "warn" mode (can live with split-lock #AC > > being randomly disabled/enabled) and userspace has communicated to KVM that > > it is pinning vCPUs. > > How about covering the actual sensible case: host is set to fatal? In this > mode, the guest gets split lock detection whether it wants it or not. How do > we communicate this to the guest? KVM doesn't advertise split-lock #AC to the guest and returns -EFAULT to the userspace VMM if the guest triggers a split-lock #AC. Effectively the same behavior as any other userspace process, just that KVM explicitly returns -EFAULT instead of the process getting a SIGBUS.
