Mask local APIC vectors on init, before enabling interrupts

[kib]

Summary

If APIC is left in somewhat bad state, with some source hot (not masked and active, e.g. timers after kexec or due to BIOS bug), we get the interrupt too early.

x86/local_apic.c: convert lvts[] and elvts[] arrays to designated initializers


x88/local_apic.c: for each lvt element, add LVT register index


x86: mask all LAPIC vectors early, before BSP interrupts are enabled

Reported by: jmg

[markj]

If APIC is left in somewhat bad state, with some source hot (not masked and active, e.g. timers after kexec or due to BIOS bug), we get the interrupt too early.

Shouldn't kexec be masking all interrupt sources before starting the new kernel?

sys/x86/x86/local_apic.c

150–208

Can we keep the const party going?

[kib]

In D54543#1246173, @markj wrote:

If APIC is left in somewhat bad state, with some source hot (not masked and active, e.g. timers after kexec or due to BIOS bug), we get the interrupt too early.

Shouldn't kexec be masking all interrupt sources before starting the new kernel?

I (strongly) believe that this is the wrong side. Kexec kernel should not care, it is the booting kernel that suffer, and it should be prepared for arbitrary state. I also mentioned the broken BIOS or VMM as an example.

To reformulate, we must correctly initialize hardware. In this case, it is currently not correct, and doing it correct is not hard.

sys/x86/x86/local_apic.c

150–208

I tried that, it does not work. E.g. lapic_enable_pcint() modifies the elements of the array.