Re: [PATCH v11 00/19] KVM: s390: pv: implement lazy destroy for reboot

From: Janosch Frank
Date: Tue Jun 14 2022 - 10:29:43 EST


On 6/3/22 08:56, Claudio Imbrenda wrote:
Previously, when a protected VM was rebooted or when it was shut down,
its memory was made unprotected, and then the protected VM itself was
destroyed. Looping over the whole address space can take some time,
considering the overhead of the various Ultravisor Calls (UVCs). This
means that a reboot or a shutdown would take a potentially long amount
of time, depending on the amount of used memory.

This patchseries implements a deferred destroy mechanism for protected
guests. When a protected guest is destroyed, its memory can be cleared
in background, allowing the guest to restart or terminate significantly
faster than before.

There are 2 possibilities when a protected VM is torn down:
* it still has an address space associated (reboot case)
* it does not have an address space anymore (shutdown case)


Please add patches 1-13 to devel for some CI coverage.
I'll try reviewing the remaining patches this week.