On Sat, Oct 10, 2020 at 01:42:26AM -0700, Nadav Amit wrote: > > > > On May 8, 2020, at 1:39 PM, Jim Mattson <jmattson@xxxxxxxxxx> wrote: > > > > When the VMX-preemption timer is activated, code executing in VMX > > non-root operation should never be able to record a TSC value beyond > > the deadline imposed by adding the scaled VMX-preemption timer value > > to the first TSC value observed by the guest after VM-entry. > > > > Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx> > > Reviewed-by: Peter Shier <pshier@xxxxxxxxxx> > > This test failed on my bare-metal machine (Broadwell): > > Test suite: vmx_preemption_timer_expiry_test > FAIL: Last stored guest TSC (44435478250637180) < TSC deadline (44435478250419552) > > Any hints why, perhaps based on the motivation for the test? This test also fails intermittently on my Haswell and Coffee Lake systems when running on KVM. I haven't done any "debug" beyond a quick glance at the test. The intent of the test is to verify that KVM injects preemption timer VM-Exits without violating the architectural guarantees of the timer, e.g. that the exit isn't delayed by something else happening in the system.
