On Sat, 14 Oct 2017 09:47:59 +1100
Paul Mackerras <pau...@ozlabs.org> wrote:

> On Sun, Aug 13, 2017 at 11:33:44AM +1000, Nicholas Piggin wrote:
> > The "lppaca" is a structure registered with the hypervisor. This
> > is unnecessary when running on non-virtualised platforms. One field
> > from the lppaca (pmcregs_in_use) is also used by the host, so move
> > the host part out into the paca (lppaca field is still updated in
> > guest mode).  
> 
> There is an error in the patch, see below...
> 
> > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S 
> > b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> > index c52184a8efdf..b838348e3a2b 100644
> > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> > @@ -99,8 +99,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
> >     mtspr   SPRN_SPRG_VDSO_WRITE,r3
> >  
> >     /* Reload the host's PMU registers */
> > -   ld      r3, PACALPPACAPTR(r13)  /* is the host using the PMU? */
> > -   lbz     r4, LPPACA_PMCINUSE(r3)
> > +   lbz     r4, PACA_PMCINUSE(r13) /* is the host using the PMU? */
> >     cmpwi   r4, 0
> >     beq     23f                     /* skip if not */
> >  BEGIN_FTR_SECTION
> > @@ -1671,7 +1670,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> >     mtspr   SPRN_MMCRA, r7
> >     isync
> >     beq     21f                     /* if no VPA, save PMU stuff anyway */
> > -   lbz     r7, LPPACA_PMCINUSE(r8)
> > +   lbz     r7, PACA_PMCINUSE(r13)  
> 
> We really do need to check the guest's flag not the host's here, since
> we're deciding whether to save the PMU state to the vcpu struct.

Okay I'll fix that up.

Thanks,
Nick

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