[PATCH 3/5 v4] KVM: PPC: Book3s: Remove kvmppc_read_inst() function

[mihai.caraman at freescale.com]

> -----Original Message-----
> From: Alexander Graf [mailto:agraf at suse.de]
> Sent: Thursday, July 03, 2014 4:37 PM
> To: Caraman Mihai Claudiu-B02008; kvm-ppc at vger.kernel.org
> Cc: kvm at vger.kernel.org; linuxppc-dev at lists.ozlabs.org
> Subject: Re: [PATCH 3/5 v4] KVM: PPC: Book3s: Remove kvmppc_read_inst()
> function
> 
> 
> On 28.06.14 00:49, Mihai Caraman wrote:
> > In the context of replacing kvmppc_ld() function calls with a version
> of
> > kvmppc_get_last_inst() which allow to fail, Alex Graf suggested this:
> >
> > "If we get EMULATE_AGAIN, we just have to make sure we go back into the
> guest.
> > No need to inject an ISI into  the guest - it'll do that all by itself.
> > With an error returning kvmppc_get_last_inst we can just use completely
> > get rid of kvmppc_read_inst() and only use kvmppc_get_last_inst()
> instead."
> >
> > As a intermediate step get rid of kvmppc_read_inst() and only use
> kvmppc_ld()
> > instead.
> >
> > Signed-off-by: Mihai Caraman <mihai.caraman at freescale.com>
> > ---
> > v4:
> >   - new patch
> >
> >   arch/powerpc/kvm/book3s_pr.c | 85 ++++++++++++++++++-----------------
> ---------
> >   1 file changed, 35 insertions(+), 50 deletions(-)
> >
> > diff --git a/arch/powerpc/kvm/book3s_pr.c
> b/arch/powerpc/kvm/book3s_pr.c
> > index 15fd6c2..d247d88 100644
> > --- a/arch/powerpc/kvm/book3s_pr.c
> > +++ b/arch/powerpc/kvm/book3s_pr.c
> > @@ -665,42 +665,6 @@ static void kvmppc_giveup_fac(struct kvm_vcpu
> *vcpu, ulong fac)
> >   #endif
> >   }
> >
> > -static int kvmppc_read_inst(struct kvm_vcpu *vcpu)
> > -{
> > -	ulong srr0 = kvmppc_get_pc(vcpu);
> > -	u32 last_inst = kvmppc_get_last_inst(vcpu);
> > -	int ret;
> > -
> > -	ret = kvmppc_ld(vcpu, &srr0, sizeof(u32), &last_inst, false);
> > -	if (ret == -ENOENT) {
> > -		ulong msr = kvmppc_get_msr(vcpu);
> > -
> > -		msr = kvmppc_set_field(msr, 33, 33, 1);
> > -		msr = kvmppc_set_field(msr, 34, 36, 0);
> > -		msr = kvmppc_set_field(msr, 42, 47, 0);
> > -		kvmppc_set_msr_fast(vcpu, msr);
> > -		kvmppc_book3s_queue_irqprio(vcpu,
> BOOK3S_INTERRUPT_INST_STORAGE);
> > -		return EMULATE_AGAIN;
> > -	}
> > -
> > -	return EMULATE_DONE;
> > -}
> > -
> > -static int kvmppc_check_ext(struct kvm_vcpu *vcpu, unsigned int
> exit_nr)
> > -{
> > -
> > -	/* Need to do paired single emulation? */
> > -	if (!(vcpu->arch.hflags & BOOK3S_HFLAG_PAIRED_SINGLE))
> > -		return EMULATE_DONE;
> > -
> > -	/* Read out the instruction */
> > -	if (kvmppc_read_inst(vcpu) == EMULATE_DONE)
> > -		/* Need to emulate */
> > -		return EMULATE_FAIL;
> > -
> > -	return EMULATE_AGAIN;
> > -}
> > -
> >   /* Handle external providers (FPU, Altivec, VSX) */
> >   static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int
> exit_nr,
> >   			     ulong msr)
> > @@ -1101,31 +1065,51 @@ program_interrupt:
> >   	case BOOK3S_INTERRUPT_VSX:
> >   	{
> >   		int ext_msr = 0;
> > +		int emul;
> > +		ulong pc;
> > +		u32 last_inst;
> >
> > -		switch (exit_nr) {
> > -		case BOOK3S_INTERRUPT_FP_UNAVAIL: ext_msr = MSR_FP;  break;
> > -		case BOOK3S_INTERRUPT_ALTIVEC:    ext_msr = MSR_VEC; break;
> > -		case BOOK3S_INTERRUPT_VSX:        ext_msr = MSR_VSX; break;
> > -		}
> > +		if (!(vcpu->arch.hflags & BOOK3S_HFLAG_PAIRED_SINGLE)) {
> 
> Please make paired single emulation the unusual, if()'ed case, not the
> normal exit path :).

Huh ... do you have more Book3s specific requests, it will be strange if
it will still work after all this blind changes :)

-Mike