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

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Message-Id: <1573031332-2121-1-git-send-email-zhenzhong.duan@oracle.com>
Date:   Wed,  6 Nov 2019 17:08:48 +0800
From:   Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     pbonzini@...hat.com, rkrcmar@...hat.com,
        rafael.j.wysocki@...el.com, joao.m.martins@...cle.com,
        mtosatti@...hat.com, Zhenzhong Duan <zhenzhong.duan@...cle.com>
Subject: [PATCH v2 0/4] misc fixes on halt-poll code both KVM and guest

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(-)

-- 
1.8.3.1