Re: [PATCH 2/2] KVM: PPC: Book3E: Emulate MCSRR0/1 SPR and rfmci instruction

[Scott Wood <scottwood@freescale.com>]

On 07/08/2013 01:45:58 PM, Alexander Graf wrote:
> 
> On 03.07.2013, at 15:30, Mihai Caraman wrote:
> 
> > Some guests are making use of return from machine check instruction
> > to do crazy things even though the 64-bit kernel doesn't handle yet
> > this interrupt. Emulate MCSRR0/1 SPR and rfmci instruction  
> accordingly.
> >
> > Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
> > ---
> > arch/powerpc/include/asm/kvm_host.h |    1 +
> > arch/powerpc/kvm/booke_emulate.c    |   25 +++++++++++++++++++++++++
> > arch/powerpc/kvm/timing.c           |    1 +
> > 3 files changed, 27 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/kvm_host.h  
> b/arch/powerpc/include/asm/kvm_host.h
> > index af326cd..0466789 100644
> > --- a/arch/powerpc/include/asm/kvm_host.h
> > +++ b/arch/powerpc/include/asm/kvm_host.h
> > @@ -148,6 +148,7 @@ enum kvm_exit_types {
> > 	EMULATED_TLBWE_EXITS,
> > 	EMULATED_RFI_EXITS,
> > 	EMULATED_RFCI_EXITS,
> > +	EMULATED_RFMCI_EXITS,
> 
> I would quite frankly prefer to see us abandon the whole exit timing  
> framework in the kernel and instead use trace points. Then we don't  
> have to maintain all of this randomly exercised code.

Would this map well to tracepoints?  We're not trying to track discrete  
events, so much as accumulated time spent in different areas.

-Scott