linux-kernel - Re: [PATCH v2 00/14] KVM: x86: change PIT discard policy and untangle related code

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Date:	Thu, 18 Feb 2016 19:11:01 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Radim Krčmář <rkrcmar@...hat.com>,
	linux-kernel@...r.kernel.org
Cc:	kvm@...r.kernel.org, Yuki Shibuya <shibuya.yk@...s.nec.co.jp>
Subject: Re: [PATCH v2 00/14] KVM: x86: change PIT discard policy and untangle
 related code



On 17/02/2016 20:14, Radim Krčmář wrote:
> v2
>  - Different ordering; the important fix is first, which makes it easier
>    to backport as improvements of [1/14] have complex dependencies.
>  - Correct choice of atomics in [2/14].
>  - Explicit SMP barriers for lockless updates in [3/14].
>  - Protection against userspace races in kvm_vm_ioctl_reinject, [8/14].
>  - New code churn.  (I tried to annotate locking, which required me to
>    really look at the code and I couldn't leave it alone at that point;
>    sorry.)
> 
> This series only works with the discard policy, do you want to "fix" NMI
> in the delay policy as well?
> (NMI delivery is still is going to be wrong by any standard, but will
>  make some sense, at the cost of ugly code:  we would always inject NMI
>  when the timer fires and suppress NMI injection on EOI reinject.)
> 
> Anatomy of the series:
>  [1/14] fixes legacy NMI watchdog under discard policy.
>  [2-7/14] prepare for optimization of the discard policy.
>  [8/14] optimizes discard policy by removing notifiers.
>  [9-14/14] slightly improve related code.
> 
> I'm ok with dropping patches [2-14/14].
> 
> v1: http://www.spinics.net/lists/kvm/msg127017.html
> 
> Radim Krčmář (14):
>   KVM: x86: change PIT discard tick policy
>   KVM: x86: simplify atomics in kvm_pit_ack_irq
>   KVM: x86: add kvm_pit_reset_reinject
>   KVM: x86: use atomic_t instead of pit.inject_lock
>   KVM: x86: tone down WARN_ON pit.state_lock
>   KVM: x86: pass struct kvm_pit instead of kvm in PIT
>   KVM: x86: remove unnecessary uses of PIT state lock
>   KVM: x86: remove notifiers from PIT discard policy
>   KVM: x86: refactor kvm_create_pit
>   KVM: x86: refactor kvm_free_pit
>   KVM: x86: remove pit and kvm from kvm_kpit_state
>   KVM: x86: remove pointless dereference of PIT
>   KVM: x86: don't assume layout of kvm_kpit_state
>   KVM: x86: move PIT timer function initialization
> 
>  arch/x86/kvm/i8254.c | 318 +++++++++++++++++++++++----------------------------
>  arch/x86/kvm/i8254.h |  15 +--
>  arch/x86/kvm/x86.c   |  52 ++++++---
>  3 files changed, 187 insertions(+), 198 deletions(-)
> 

Patches 1 and 9-14:

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>

Thanks!

Paolo