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SubjectRe: [PATCH 0/4 V13] Avoid soft lockup message when KVM is stopped by host
On Mon, 5 Mar 2012 13:39:43 -0300, 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@amt.cnet>, 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.


Okay, that will go into V16 then...

Eric


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