Re: [PATCH 0/4 V13] Avoid soft lockup message when KVM is stopped byhost

[Eric B Munson]

On Mon, 05 Mar 2012, Marcelo Tosatti wrote:

> On Tue, Feb 14, 2012 at 04:17:20PM -0500, Eric B Munson wrote:
> > On Tue, 14 Feb 2012, Marcelo Tosatti wrote:
> > 
> > > On Tue, Feb 14, 2012 at 10:50:13AM -0500, Eric B Munson wrote:
> > > > On Tue, 14 Feb 2012, Marcelo Tosatti wrote:
> > > > 
> > > > > On Tue, Feb 14, 2012 at 10:29:31AM -0500, Eric B Munson wrote:
> > > > > > 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,
> > > > > 
> > > > > On Message-ID: <20120210160536.GA23363@xxxxxxxx>, i asked:
> > > > > 
> > > > > How is the stub getting included for other architectures again?
> > > > > 
> > > > 
> > > > Marcelo,
> > > > 
> > > > Sorry, I put out V13 to answer that.  There is a stub in asm-generic that was
> > > > lost in the V11-V12 rebase.  This stub has be included in the V13 set.
> > > > 
> > > > Eric
> > > 
> > > Eric, 
> > > 
> > > I know the stub has been included in the series. But i am asking how 
> > > it is #include'ed for other architectures? (can't see that).
> > 
> > Marcelo,
> > 
> > kernel/watchdog.c now includes linux/kvm_para.h which includes asm/kvm_para.h.
> > The check_and_clear function is defined in arch include/asm/kvm_para.h or in
> > asm-generic/kvm_para.h for any arch lacking the specific header in their asm
> > include dir.  If I have misunderstood how these headers work, please let me
> > know and I will fix it.
> 
> There is no automatic inclusion of asm-generic/ headers. You must create
> kvm_para.h in each architecture's include/asm/ directory, #including
> asm-generic/kvm_para.h.
> 

Hopefully V16 handles this properly, please let me know if there is anything
that needs to be addressed.  I'd like to see this set in for the 3.4 window.

Eric

Attachment: signature.asc
Description: Digital signature