0cdd3d1444 fixed reading back the counter load time from the kernel
while assuming the kernel would always update its load time on writing
the state. That is only true for channel 1, and so pit_get_channel_info
returned wrong output pin states for high counter values.
Fix this by applying the offset also on kvm_pit_put. Now we also need to
update the offset when we write the state while the VM is stopped as it
keeps on changing in that state.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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>
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>
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>
