On 14/11/2016 13:36, Marcelo Tosatti wrote:
> + /* local (running VM) restore */
> + if (s->clock_valid) {
> + /*
> + * if host does not support reliable KVM_GET_CLOCK,
> + * read kvmclock value from memory
> + */
> + if (!kvm_has_adjust_clock_stable()) {
> + time_at_migration = kvmclock_current_nsec(s);
Just assign to s->clock here...
> + }
> + /* migration/savevm/init restore */
> + } else {
> + /*
> + * use s->clock in case machine uses reliable
> + * get clock and host where vm was executing
> + * supported reliable get clock
> + */
> + if (!s->mach_use_reliable_get_clock ||
> + !s->src_use_reliable_get_clock) {
> + time_at_migration = kvmclock_current_nsec(s);
... and here, so that time_at_migration is not needed anymore.
Also here it's enough to look at s->src_user_reliable_get_clock, because
if s->mach_use_reliable_get_clock is false,
s->src_use_reliable_get_clock will be false as well.
> + }
> + }
>
> - /* We can't rely on the migrated clock value, just discard it */
> + /* We can't rely on the saved clock value, just discard it */
> if (time_at_migration) {
> s->clock = time_at_migration;
[...]
>
> +static bool kvmclock_src_use_reliable_get_clock(void *opaque)
> +{
> + KVMClockState *s = opaque;
> +
> + /*
> + * On machine types that support reliable KVM_GET_CLOCK,
> + * if host kernel does provide reliable KVM_GET_CLOCK,
> + * set src_use_reliable_get_clock=true so that destination
> + * avoids reading kvmclock from memory.
> + */
> + if (s->mach_use_reliable_get_clock && kvm_has_adjust_clock_stable()) {
> + s->src_use_reliable_get_clock = true;
> + }
> +
> + return s->src_use_reliable_get_clock;
> +}
Here you can just return s->mach_use_reliable_get_clock. To set
s->src_use_reliable_get_clock, after issuing KVM_GET_CLOCK you can look
at the KVM_CLOCK_TSC_STABLE bit in the kvm_clock struct's flags.
You don't actually need kvm_has_adjust_clock_stable(), but please place
the KVM_GET_CLOCK code for kvmclock_pre_save and
kvmclock_vm_state_change in a common function.
Also, just another small nit: please make your scripts use the "-p"
option on diff. :)
Thanks,
Paolo
