Re: [RFC PATCH v3 17/21] KVM: x86: Avoid global clock update on setting KVM clock MSR

[Paul Durrant]

On 22/05/2024 01:17, David Woodhouse wrote:
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
>
> Commit 0061d53daf26 ("KVM: x86: limit difference between kvmclock updates")
> introduced a KVM_REQ_GLOBAL_CLOCK_UPDATE when one vCPU set up its clock.
>
> This was a workaround for the ever-drifting clocks which were based on the
> host's CLOCK_MONOTONIC and thus subject to NTP skew. On booting or resuming
> a guest, it just leads to running kvm_guest_time_update() twice for each
> vCPU for now good reason.
>
> Just use KVM_REQ_CLOCK_UPDATE on the vCPU itself, and only in the case
> where the KVM clock is being set up, not turned off.
>
> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> ---
>   arch/x86/kvm/x86.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: Paul Durrant <paul@xxxxxxx>