Re: [PATCH V1 00/32] Live Update

[Paolo Bonzini]

On 30/07/20 17:14, Steve Sistare wrote:
> The first set of patches adds the cprsave and cprload commands to save and
> restore VM state, and allow the host kernel to be updated and rebooted in
> between.  The VM must create guest RAM in a persistent shared memory file,
> such as /dev/dax0.0 or persistant /dev/shm PKRAM as proposed in 
> https://lore.kernel.org/lkml/1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com/
> 
> cprsave stops the VCPUs and saves VM device state in a simple file, and
> thus supports any type of guest image and block device.  The caller must
> not modify the VM's block devices between cprsave and cprload.

Stupid question, what does cpr stand for?  If it is checkpoint/restore,
please spell it out.  Also, how does the functionality compare to
xen-save-devices-state and xen-load-devices-state?

> cprsave and cprload support guests with vfio devices if the caller first
> suspends the guest by issuing guest-suspend-ram to the qemu guest agent.
> The guest drivers suspend methods flush outstanding requests and re-
> initialize the devices, and thus there is no device state to save and
> restore.

This probably should be allowed even for regular migration.  Can you
generalize the code as a separate series?

Thanks,

Paolo