From mboxrd@z Thu Jan  1 00:00:00 1970
From: Greg KH <greg@kroah.com>
Subject: Re: 4.14.18 -> 4.14.24 - almost all guests hanged
Date: Thu, 8 Mar 2018 06:17:14 -0800
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To: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
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On Wed, Mar 07, 2018 at 09:29:10PM +0100, Nikola Ciprich wrote:
> Hi,
> 
> > > > I'd like to report that when upgrading our cluster from 4.14.18 to
> > > >  4.14.24-rc1 (with live guests migration), almost none of guests survived..
> > > What's your hardware setup, intel with IBPB enabled microcode?
> > Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz
> > 
> > therefore I suppose no IBPB (at least meltdown checker reports so)
> > 
> > 
> > > Does guests hang right after live migration?
> > yes, just  tried it.
> > 
> > 
> > > 
> > > Are you able to reproduce the problem, does it work with latest upstream?
> > yup, so I'm able to reproduce quickly. I'll revert the cluster to 4.14.18 now,
> > but setup test system just afterwards, so and test the patch you've proposed.
> > 
> > > 
> > > Not sure it helps, but following patch is missing in 4.14.24
> > > 
> > > commit 37b95951c58fdf08dc10afa9d02066ed9f176fb5 upstream.
> > > 
> > > kvm_valid_sregs() should use X86_CR0_PG and X86_CR4_PAE to check bit
> > > status rather than X86_CR0_PG_BIT and X86_CR4_PAE_BIT. This patch is
> > > to fix it.
> > > 
> > > Fixes: f29810335965a(KVM/x86: Check input paging mode when cs.l is set)
> > > Reported-by: Jeremi Piotrowski <jeremi.piotrowski@gmail.com>
> > > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > > Cc: Radim Krčmář <rkrcmar@redhat.com>
> > > Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
> > > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> > 
> > I'll test and report.
> 
> so indeed, this one on top of 4.14.24-rc1 fixes the migration for me.
> Greg, could you queue this one up please?

As was already pointed out, this is already queued up to be in the next
release.

thanks,

greg k-h