Commit Graph

3 Commits

Author SHA1 Message Date
Jan Kiszka
205df4d1a8 kvm: i8254: Cache kernel clock offset in KVMPITState
To prepare the final fix for clock calibration issues with the in-kernel
PIT, we want to cache the offset between vmclock and the clock used by
the in-kernel PIT. So far, we only need to update it when the VM state
changes between running and stopped because we only read the in-kernel
PIT state while the VM is running.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-08-14 19:23:16 -03:00
Jan Kiszka
0cdd3d1444 kvm: i8254: Fix conversion of in-kernel to userspace state
Due to a offset between the clock used to generate the in-kernel
count_load_time (CLOCK_MONOTONIC) and the clock used for processing this
in userspace (vm_clock), reading back the output of PIT channel 2 via
port 0x61 was broken. One use cases that suffered from it was the CPU
frequency calibration of SeaBIOS, which also affected IDE/AHCI timeouts.

This fixes it by calibrating the offset between both clocks on
kvm_pit_get and adjusting the kernel value before saving it in the
userspace state. As the calibration only works while the vm_clock is
running, we cache the in-kernel state across stopped phases.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2012-06-11 14:18:23 +03:00
Jan Kiszka
5d17c0d2df kvm: x86: Add user space part for in-kernel i8254
This provides the required user space stubs to enable the in-kernel
i8254 emulation of KVM.

The in-kernel model supports lost tick compensation according to the
"delay" policy. This is enabled by default and can be switched off via a
device property.

Depending on the feature set of the host kernel (before 2.6.32), we may
have to disable the HPET or lack sound output from the PC speaker.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2012-03-07 12:27:43 +02:00