While not mandated by any specification, Linux systems rely on NMIs (Non-maskable Interrupts) being blocked by an IF-enabling (Interrupt Flag) STI instruction (an x86 instruction that enables interrupts; Set Interrupts); this is also the common behavior of all known hardware. Prior to this update, kernel panic could occur on guests using NMIs extensively (for example, a Linux system with the nmi_watchdog kernel parameter enabled). With this update, an NMI is disallowed when interrupts are blocked by an STI. This is done by checking for the condition and requesting an interrupt window exit if it occurs. As a result, kernel panic no longer occurs.