Comment 3 for bug 1817918

Tested kernel in -proposed, version 4.4.0-144-generic (in Xenial). Problem does not reproduce anymore.

I've used tscdeadline_delay test wrote by Thadeu Cascardo as a kvm-unit-tests "module" - this specific test is not upstream yet, Cascardo wrote for this LP in particular and is finishing/polishing before submission. As soon as it gets merged, I'll point the link here for reference.

In summary, I ran the test against 4.4.0-143, which gave me this output:

$ ./x86/run x86/tscdeadline_delay.flat -smp 1 -cpu host,+tsc-deadline

/usr/bin/qemu-system-x86_64 -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel x86/tscdeadline_delay.flat -smp 1 -cpu host,+tsc-deadline # -initrd /tmp/tmp.bDXlFhhhBJ

enabling apic
paging enabled
cr0 = 80010011
cr3 = 458000
cr4 = 20
apic version: 50014
PASS: apic existence
tsc deadline timer enabled
FAIL: delta: 4294968162

SUMMARY: 2 tests, 1 unexpected failures

After that, I've rebooted the machine and tested against 4.4.0-144:

$ ./x86/run x86/tscdeadline_delay.flat -smp 1 -cpu host,+tsc-deadline

/usr/bin/qemu-system-x86_64 -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel x86/tscdeadline_delay.flat -smp 1 -cpu host,+tsc-deadline # -initrd /tmp/tmp.qQvOapKgzp

enabling apic
paging enabled
cr0 = 80010011
cr3 = 458000
cr4 = 20
apic version: 50014
PASS: apic existence
tsc deadline timer enabled
PASS: no large delta
SUMMARY: 2 tests