CVSROOT: /cvs
Module name: src
Changes by: d...@cvs.openbsd.org 2023/01/30 14:43:12
Modified files:
usr.sbin/vmd : ns8250.c
Log message:
vmd(8): fix an interrupt storm in ns8250.
On slower hosts, such as those in a nested virtualization scenario
of OpenBSD guest inside OpenBSD atop Linux KVM, ns8250 can cause a
race between the kevent firing and the vcpu being kicked by an
assert/deassert of the irq.
The end user experiences a "stuck" serial console and the host will
see a vmd process peg the cpu.
This change only toggles the irq if we were in a position of being
ready to receive data on the device so while the kevent might
continuously fire, the vcpu will not be kicked repeatedly.
OK mlarkin@
