- /* Clear the freeze bit, and reenable the interrupt.
- * The counters won't actually start until the rfi clears
- * the PMM bit */
+ /* Clear the freeze bit, and reenable the interrupt. The
+ * counters won't actually start until the rfi clears the PMM
+ * bit. The PMM bit should not be set until after the interrupt
+ * is cleared to avoid it getting lost in some hypervisor
+ * environments.
+ */
+ mtmsr(mfmsr() | MSR_PMM);