linux-kernel - Re: [PATCH 0/4 V13] Avoid soft lockup message when KVM is stopped by host

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Message-ID: <20120214152931.GA6881@mgebm.net>
Date:	Tue, 14 Feb 2012 10:29:31 -0500
From:	Eric B Munson <emunson@...bm.net>
To:	avi@...hat.com
Cc:	mingo@...hat.com, hpa@...or.com, ryanh@...ux.vnet.ibm.com,
	aliguori@...ibm.com, mtosatti@...hat.com, kvm@...r.kernel.org,
	linux-arch@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4 V13] Avoid soft lockup message when KVM is stopped by
 host

On Wed, 08 Feb 2012, Eric B Munson wrote:

> 
> When a guest kernel is stopped by the host hypervisor it can look like a soft
> lockup to the guest kernel.  This false warning can mask later soft lockup
> warnings which may be real.  This patch series adds a method for a host
> hypervisor to communicate to a guest kernel that it is being stopped.  The
> final patch in the series has the watchdog check this flag when it goes to
> issue a soft lockup warning and skip the warning if the guest knows it was
> stopped.
> 
> It was attempted to solve this in Qemu, but the side effects of saving and
> restoring the clock and tsc for each vcpu put the wall clock of the guest behind
> by the amount of time of the pause.  This forces a guest to have ntp running
> in order to keep the wall clock accurate.

Avi,

Is this set fit for merging or is there something else you want changed?

Eric

> 
> Cc: mingo@...hat.com
> Cc: hpa@...or.com
> Cc: ryanh@...ux.vnet.ibm.com
> Cc: aliguori@...ibm.com
> Cc: mtosatti@...hat.com
> Cc: kvm@...r.kernel.org
> Cc: linux-arch@...r.kernel.org
> Cc: x86@...nel.org
> Cc: linux-kernel@...r.kernel.org
> 
> Eric B Munson (4):
>   Add flag to indicate that a vm was stopped by the host
>   Add functions to check if the host has stopped the vm
>   Add ioctl for KVM_KVMCLOCK_CTRL
>   Add check for suspended vm in softlockup detector
> 
>  Documentation/virtual/kvm/api.txt   |   13 +++++++++++++
>  arch/ia64/include/asm/kvm_para.h    |    5 +++++
>  arch/powerpc/include/asm/kvm_para.h |    5 +++++
>  arch/s390/include/asm/kvm_para.h    |    5 +++++
>  arch/x86/include/asm/kvm_para.h     |    8 ++++++++
>  arch/x86/include/asm/pvclock-abi.h  |    1 +
>  arch/x86/kernel/kvmclock.c          |   21 +++++++++++++++++++++
>  arch/x86/kvm/x86.c                  |   22 ++++++++++++++++++++++
>  include/asm-generic/kvm_para.h      |   14 ++++++++++++++
>  include/linux/kvm.h                 |    3 +++
>  kernel/watchdog.c                   |   12 ++++++++++++
>  11 files changed, 109 insertions(+), 0 deletions(-)
>  create mode 100644 include/asm-generic/kvm_para.h
> 
> -- 
> 1.7.5.4
> 

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