From mboxrd@z Thu Jan  1 00:00:00 1970
From: Scott Wood <scottwood@freescale.com>
Subject: Re: [PATCH 1/3] KVM: PPC: e500: Call kvmppc_mmu_map for initial
 mapping
Date: Thu, 17 Jan 2013 18:47:15 -0600
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Cc: <kvm-ppc@vger.kernel.org>, <kvm@vger.kernel.org>
To: Alexander Graf <agraf@suse.de>
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In-Reply-To: <F75E090F-2AE5-483E-BCDE-E9FAED2415ED@suse.de> (from
	agraf@suse.de on Thu Jan 17 18:20:03 2013)
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On 01/17/2013 06:20:03 PM, Alexander Graf wrote:
>=20
> On 18.01.2013, at 01:11, Scott Wood wrote:
>=20
> > On 01/17/2013 04:50:39 PM, Alexander Graf wrote:
> >> @@ -1024,9 +1001,11 @@ void kvmppc_mmu_map(struct kvm_vcpu *vcpu, =
=20
> u64 eaddr, gpa_t gpaddr,
> >> {
> >> 	struct kvmppc_vcpu_e500 *vcpu_e500 =3D to_e500(vcpu);
> >> 	struct tlbe_priv *priv;
> >> -	struct kvm_book3e_206_tlb_entry *gtlbe, stlbe;
> >> +	struct kvm_book3e_206_tlb_entry *gtlbe, stlbe =3D {};
> >
> > Is there a code path in which stlbe gets used but not fully filled =
=20
> in
> > without this?
>=20
> I am hoping not, but when I wrote this patch gcc suddenly jumped at =20
> me claiming that the whole struct can get used uninitialized:
>=20
> arch/powerpc/kvm/e500_mmu_host.c: In function =E2=80=98kvmppc_mmu_map=
=E2=80=99:
> arch/powerpc/kvm/e500_mmu_host.c:533: error: =E2=80=98stlbe.mas1=E2=80=
=99 may be used =20
> uninitialized in this function
> arch/powerpc/kvm/e500_mmu_host.c:533: error: =E2=80=98stlbe.mas2=E2=80=
=99 may be used =20
> uninitialized in this function
> arch/powerpc/kvm/e500_mmu_host.c:533: error: =E2=80=98stlbe.mas7_3=E2=
=80=99 may be =20
> used uninitialized in this function
> arch/powerpc/kvm/e500_mmu_host.c:533: error: =E2=80=98stlbe.mas8=E2=80=
=99 may be used =20
> uninitialized in this function
>=20
> If you have any idea where this could come from, please let me know =20
> :).

I can't reproduce with either GCC 4.5.1 or GCC 4.7.2.  Maybe from a =20
non-final version of the patch?  It would be nice to not have this, and=
 =20
have GCC be able to detect if we're actually missing something rather =20
than have it get zeroed.

BTW, it's "stlbe =3D {}" in this patch but after the file split, someho=
w =20
come out as "stlbe =3D { }".  Was that patch supposed to be just a simp=
le =20
cut and paste of part of the file?

-Scott