On Wed, Dec 09, 2020 at 09:58:23PM +0100, Thomas Gleixner wrote:
Marcelo,
On Wed, Dec 09 2020 at 13:34, Marcelo Tosatti wrote:
On Tue, Dec 08, 2020 at 10:33:15PM +0100, Thomas Gleixner wrote:
On Tue, Dec 08 2020 at 15:11, Marcelo Tosatti wrote:
max_cycles overflow. Sent a message to Maxim describing it.
Truly helpful. Why the hell did you not talk to me when you ran into that the first time?
Because
- Users wanted CLOCK_BOOTTIME to stop counting while the VM
is paused (so we wanted to stop guest clock when VM is paused anyway).
How is that supposed to work w/o the guest kernels help if you have to keep clock realtime up to date?
Upon VM resume, we notify NTP daemon in the guest to sync realtime clock.
- The solution to inject NMIs to the guest seemed overly
complicated.
Why do you need NMIs?
All you need is a way to communicate to the guest that it should prepare for clock madness to happen. Whether that's an IPI or a bit in a hyperpage which gets checked during the update of the guest timekeeping does not matter at all.
But you certainly do not need an NMI because there is nothing useful you can do within an NMI.
Thanks,
tglx