-----Original Message-----
From: Alexander Graf [mailto:agraf@suse.de]
Sent: Thursday, July 03, 2014 4:37 PM
To: Caraman Mihai Claudiu-B02008; kvm-ppc@vger.kernel.org
Cc: kvm@vger.kernel.org; linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 3/5 v4] KVM: PPC: Book3s: Remove kvmppc_read_inst()
function
=20
=20
On 28.06.14 00:49, Mihai Caraman wrote:

quoted

In the context of replacing kvmppc_ld() function calls with a version

of

quoted

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.

quoted

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."

quoted

As a intermediate step get rid of kvmppc_read_inst() and only use

kvmppc_ld()

quoted

instead.

Signed-off-by: Mihai Caraman <redacted>
---
v4:
  - new patch

  arch/powerpc/kvm/book3s_pr.c | 85 ++++++++++++++++++-----------------

---------

quoted

  1 file changed, 35 insertions(+), 50 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_pr.c

b/arch/powerpc/kvm/book3s_pr.c

quoted

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)

quoted

  #endif
  }

-static int kvmppc_read_inst(struct kvm_vcpu *vcpu)
-{
-	ulong srr0 =3D kvmppc_get_pc(vcpu);
-	u32 last_inst =3D kvmppc_get_last_inst(vcpu);
-	int ret;
-
-	ret =3D kvmppc_ld(vcpu, &srr0, sizeof(u32), &last_inst, false);
-	if (ret =3D=3D -ENOENT) {
-		ulong msr =3D kvmppc_get_msr(vcpu);
-
-		msr =3D kvmppc_set_field(msr, 33, 33, 1);
-		msr =3D kvmppc_set_field(msr, 34, 36, 0);
-		msr =3D kvmppc_set_field(msr, 42, 47, 0);
-		kvmppc_set_msr_fast(vcpu, msr);
-		kvmppc_book3s_queue_irqprio(vcpu,

BOOK3S_INTERRUPT_INST_STORAGE);

quoted

-		return EMULATE_AGAIN;
-	}
-
-	return EMULATE_DONE;
-}
-
-static int kvmppc_check_ext(struct kvm_vcpu *vcpu, unsigned int

exit_nr)

quoted

-{
-
-	/* 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) =3D=3D 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,

quoted

  			     ulong msr)

@@ -1101,31 +1065,51 @@ program_interrupt:
  	case BOOK3S_INTERRUPT_VSX:
  	{
  		int ext_msr =3D 0;
+		int emul;
+		ulong pc;
+		u32 last_inst;

-		switch (exit_nr) {
-		case BOOK3S_INTERRUPT_FP_UNAVAIL: ext_msr =3D MSR_FP;  break;
-		case BOOK3S_INTERRUPT_ALTIVEC:    ext_msr =3D MSR_VEC; break;
-		case BOOK3S_INTERRUPT_VSX:        ext_msr =3D MSR_VSX; break;
-		}
+		if (!(vcpu->arch.hflags & BOOK3S_HFLAG_PAIRED_SINGLE)) {

=20
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