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Date: Wed, 24 Jul 2013 18:21:25 +0300
From: Gleb Natapov <gleb@redhat.com>
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Subject: Re: [Qemu-devel] VM can not boot after commit 235e898
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Jordan Justen <jordan.l.justen@intel.com>, Alexander Graf <agraf@suse.de>, Dunrong Huang <riegamaths@gmail.com>, qemu-devel Developers <qemu-devel@nongnu.org>, Hannes Reinecke <hare@suse.de>, Jordan Justen <jljusten@gmail.com>

On Wed, Jul 24, 2013 at 05:16:09PM +0200, Paolo Bonzini wrote:
> Il 24/07/2013 11:58, Alexander Graf ha scritto:
> >> > No QEMU or kvm crashes, no error message printed, I mean it just hangs, even no BIOS information are printed.
> >> > And "top" shows QEMU consumes 100% cpu.
> >> > 
> >> > When I define DEBUG_KVM in kvm-all.c, and run QEMU(this time I boot a normal OS disk), 
> >> > # x86_64-softmmu/qemu-system-x86_64 -enable-kvm -hda /mnt/nfs/Images/debian-append.img
> >> > kvm_init_vcpu
> >> > kvm_cpu_exec()
> >> > handle_io
> >> > handle_io
> >> > handle_io
> >> > handle_io
> >> > 
> >> > Only 4 debug messages(handle_io) are printed, then nothing is shown, and "top" shows QEMU process uses 100% CPU.
> > After this we're running in an endless loop of:
> > 
> >  qemu-system-x86-9298  [003] ...1 162090.918845: kvm_emulate_insn: f0000:c489:66 ea 91 c4 0f 00 08 00 (prot16)
> >  qemu-system-x86-9298  [003] d..2 162090.918846: kvm_entry: vcpu 0
> > 
> >   (qemu) x /i $pc
> >   0x00000000000fc489:  ljmpl  $0x8,$0xfc491
> > 
> > With current master, qemu-system-x86_64 -enable-kvm is broken on at least 3.7 kernels (openSUSE 12.3).
> > 
> > Gleb, I don't remember all the glorious details of ljmpl, but would it have to raise an MMIO request for a read-only memory slot which it fails to do?
> 
> The point of KVM_CAP_READONLY_MEM should be that it doesn't.
> 
Yes, it should not. Can you provide complete trace of kvm and kvmmmu
event up until failure?

--
			Gleb.