From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3wY8rG10wkzDqLj for ; Thu, 25 May 2017 10:13:50 +1000 (AEST) Message-ID: <1495671229.18002.1.camel@neuling.org> Subject: Re: [PATCH] powerpc: Fix booting P9 hash with CONFIG_PPC_RADIX_MMU=N From: Michael Neuling To: "Aneesh Kumar K.V" , mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, anton@samba.org, Greg Johnson Date: Thu, 25 May 2017 10:13:49 +1000 In-Reply-To: <87bmqir5tl.fsf@skywalker.in.ibm.com> References: <20170524070326.13531-1-mikey@neuling.org> <87bmqir5tl.fsf@skywalker.in.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2017-05-24 at 14:26 +0530, Aneesh Kumar K.V wrote: > Michael Neuling writes: >=20 > > Currently if you disable CONFIG_PPC_RADIX_MMU you'll crash on boot on > > a P9. This is because we still set MMU_FTR_TYPE_RADIX via > > ibm,pa-features and MMU_FTR_TYPE_RADIX is what's used for code patching > > in much of the asm code (ie. slb_miss_realmode) > >=20 > > This patch fixes the problem by stopping MMU_FTR_TYPE_RADIX from being > > set from ibm.pa-features. > >=20 > > We may eventually end up removing the CONFIG_PPC_RADIX_MMU option > > completely but until then this fixes the issue. > >=20 > > Signed-off-by: Michael Neuling > > --- > > =C2=A0arch/powerpc/kernel/prom.c | 2 ++ > > =C2=A01 file changed, 2 insertions(+) > >=20 > > diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c > > index 40c4887c27..f830562974 100644 > > --- a/arch/powerpc/kernel/prom.c > > +++ b/arch/powerpc/kernel/prom.c > > @@ -161,7 +161,9 @@ static struct ibm_pa_feature { > > =C2=A0 { .pabyte =3D 0,=C2=A0=C2=A0.pabit =3D 3, .cpu_features=C2=A0=C2= =A0=3D CPU_FTR_CTRL }, > > =C2=A0 { .pabyte =3D 0,=C2=A0=C2=A0.pabit =3D 6, .cpu_features=C2=A0=C2= =A0=3D CPU_FTR_NOEXECUTE }, > > =C2=A0 { .pabyte =3D 1,=C2=A0=C2=A0.pabit =3D 2, .mmu_features=C2=A0=C2= =A0=3D MMU_FTR_CI_LARGE_PAGE > > }, > > +#ifdef CONFIG_PPC_RADIX_MMU > > =C2=A0 { .pabyte =3D 40, .pabit =3D 0, .mmu_features=C2=A0=C2=A0=3D MMU= _FTR_TYPE_RADIX }, > > +#endif > > =C2=A0 { .pabyte =3D 1,=C2=A0=C2=A0.pabit =3D 1, .invert =3D 1, .cpu_fe= atures =3D > > CPU_FTR_NODSISRALIGN }, > > =C2=A0 { .pabyte =3D 5,=C2=A0=C2=A0.pabit =3D 0, .cpu_features=C2=A0=C2= =A0=3D CPU_FTR_REAL_LE, > > =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0.cpu_user_ftrs =3D PPC_FEATURE_TRUE_L= E }, > > --=C2=A0 > > 2.11.0 >=20 > Instead can we do that feature removal in mmu_early_init_devtree. ie, > something like It looks like mmu_early_init_devtree() gets called after parsing ibm,pa_fea= tures so that should work. > diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c > index 8f6f2a173e47..8f43f3827bac 100644 > --- a/arch/powerpc/mm/init_64.c > +++ b/arch/powerpc/mm/init_64.c > @@ -394,7 +394,7 @@ void __init mmu_early_init_devtree(v > oid) > =C2=A0{ > =C2=A0 /* Disable radix mode based on kernel command line. */ > =C2=A0 /* We don't yet have the machinery to do radix as a guest. */ > - if (disable_radix || !(mfmsr() & MSR_HV)) > > + if (!IS_ENABLED(CONFIG_PPC_RADIX_MMU) || disable_radix || !(mfmsr() &= MSR_HV)) What tree is this patch against? Linus' tree doesn't look like that. Mikey > =C2=A0 cur_cpu_spec->mmu_features &=3D ~MMU_FTR_TYPE_RADIX; > =C2=A0 > =C2=A0 /* >=20