Re: [nvmx testing, linux on linux] Disabling EPT in L1 renders L2 stuck on boot

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On Mon, Oct 7, 2013 at 6:29 PM, Kashyap Chamarthy <kashyap.cv@xxxxxxxxx> wrote:
> Gleb, so I just did a trace of KVM MMU to try to understand why L2 is
> stuck with shadow on EPT

Paolo, were you able to reproduce this again? Yesterday, on #qemu you
mentioned you'll test it again :-)

I was using kvm.git  queue on both L0 and L1:

  $ git describe ; git log | head -1
  for-linus-11227-g8a3c1a33
  commit 8a3c1a33476f6bfebd07954e2277dbc88003bd37

/kashyap

>
> Ensure, EPT is enabled on L0 & disabled on L1
>
> On L0:
> ---------
>   $ cat /sys/module/kvm_intel/parameters/ept
>   Y
>
> On L1
> ---------
>   $ cat /sys/module/kvm_intel/parameters/ept
>   N
>
> Build and install trace-cmd on L1:
>
>   $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/trace-cmd.git
> trace-cmd
>   $ make && sudo make-install
>
> Run trace command (on L1) to capture kvmmmu event:
>
>   $ trace-cmd record -b 2000 -e kvmmmu
>   /sys/kernel/debug/tracing/events/kvmmmu/filter
>   /sys/kernel/debug/tracing/events/*/kvmmmu/filter
>   Hit Ctrl^C to stop recording
>
> Boot L2 guest:
>
>   $ virsh start nguest-01 --console
>
> After a minute or two, ctl-C the trace-cmd, generate the report:
>
>   $ trace-cmd report
>   version = 6
>   trace-cmd: No such file or directory
>     function is_writable_pte not defined
>   CPU 1 is empty
>   CPU 2 is empty
>   CPU 3 is empty
>   cpus=4
>    qemu-system-x86-2554  [000] 90667.995345:
> kvm_mmu_invalidate_zap_all_pages: kvm-mmu-valid-gen 0 used_pages 0
>    qemu-system-x86-2557  [000] 90668.078978: kvm_mmu_get_page:     new
> sp gfn 0 0/2 q0 direct --- !pge !nxe root 0 sync
>    qemu-system-x86-2557  [000] 90668.078980: kvm_mmu_get_page:     new
> sp gfn 40000 0/2 q0 direct --- !pge !nxe root 0 sync
>    qemu-system-x86-2557  [000] 90668.078980: kvm_mmu_get_page:     new
> sp gfn 80000 0/2 q0 direct --- !pge !nxe root 0 sync
>    qemu-system-x86-2557  [000] 90668.078981: kvm_mmu_get_page:     new
> sp gfn c0000 0/2 q0 direct --- !pge !nxe root 0 sync
>    qemu-system-x86-2557  [000] 90668.079025: kvm_mmu_get_page:     new
> sp gfn 0 0/1 q0 direct --- !pge !nxe root 0 sync
>
> Side question:  I wonder why would trace-cmd say "trace-cmd: No such
> file or directory"?
>
> /kashyap
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