linux-kernel - Re: [PATCH v2 0/4] misc fixes on halt-poll code both KVM and guest

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Message-ID: <32fce2c2-9056-b4ab-1bfb-3f4b69f30da6@intel.com>
Date:   Wed, 6 Nov 2019 12:05:55 +0100
From:   "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
To:     Zhenzhong Duan <zhenzhong.duan@...cle.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     pbonzini@...hat.com, rkrcmar@...hat.com, joao.m.martins@...cle.com,
        mtosatti@...hat.com
Subject: Re: [PATCH v2 0/4] misc fixes on halt-poll code both KVM and guest

On 11/6/2019 10:08 AM, Zhenzhong Duan wrote:
> This patchset tries to fix below issues:
>
> 1. Admin could set halt_poll_ns to 0 at runtime to disable poll and kernel
> behave just like the generic halt driver. Then If guest_halt_poll_grow_start
> is set to 0 and guest_halt_poll_ns set to nonzero later, cpu_halt_poll_us will
> never grow beyond 0. The first two patches fix this issue from both kvm and
> guest side.
>
> 2. guest_halt_poll_grow_start and guest_halt_poll_ns could be adjusted at
> runtime by admin, this could make a window where cpu_halt_poll_us jump out
> of the boundary. the window could be long in some cases(e.g. guest_halt_poll_grow_start
> is bumped and cpu_halt_poll_us is shrinking) The last two patches fix this
> issue from both kvm and guest side.
>
> 3. The 4th patch also simplifies branch check code.
>
> v2:
> Rewrite the patches and drop unnecessory changes
>
> Zhenzhong Duan (4):
>    cpuidle-haltpoll: ensure grow start value is nonzero
>    KVM: ensure grow start value is nonzero
>    cpuidle-haltpoll: ensure cpu_halt_poll_us in right scope
>    KVM: ensure vCPU halt_poll_us in right scope
>
>   drivers/cpuidle/governors/haltpoll.c | 50 ++++++++++++++++++++++++-----------
>   virt/kvm/kvm_main.c                  | 51 ++++++++++++++++++++++++------------
>   2 files changed, 68 insertions(+), 33 deletions(-)
>
Please resend the series with CCs to linux-pm@...r.kernel.org, thanks!