Re: [PATCH v4 05/10] KVM: arm64: Support stolen time reporting via shared structure

From: Zenghui Yu
Date: Tue Sep 03 2019 - 05:19:03 EST

On 2019/8/30 16:42, Steven Price wrote:
Implement the service call for configuring a shared structure between a
VCPU and the hypervisor in which the hypervisor can write the time
stolen from the VCPU's execution time by other tasks on the host.

The hypervisor allocates memory which is placed at an IPA chosen by user

It seems that no allocation happens in the hypervisor code. User space
will do it instead?

The hypervisor then updates the shared structure using
kvm_put_guest() to ensure single copy atomicity of the 64-bit value
reporting the stolen time in nanoseconds.

Whenever stolen time is enabled by the guest, the stolen time counter is

The stolen time itself is retrieved from the sched_info structure
maintained by the Linux scheduler code. We enable SCHEDSTATS when
selecting KVM Kconfig to ensure this value is meaningful.

Signed-off-by: Steven Price <steven.price@xxxxxxx>