From: Scott Wood <scottwood@freescale•com>
To: David Gibson <david@gibson•dropbear.id.au>
Cc: kvm@vger•kernel.org, Alexey Kardashevskiy <aik@ozlabs•ru>,
linux-kernel@vger•kernel.org, kvm-ppc@vger•kernel.org,
Alexander Graf <agraf@suse•de>, Paul Mackerras <paulus@samba•org>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling
Date: Tue, 28 May 2013 11:32:53 -0500 [thread overview]
Message-ID: <1369758773.18630.1@snotra> (raw)
In-Reply-To: <20130525024524.GA6112@boomeroo.fritz.box> (from david@gibson.dropbear.id.au on Fri May 24 21:45:24 2013)
On 05/24/2013 09:45:24 PM, David Gibson wrote:
> On Wed, May 22, 2013 at 04:06:57PM -0500, Scott Wood wrote:
> > On 05/20/2013 10:06:46 PM, Alexey Kardashevskiy wrote:
> > >diff --git a/arch/powerpc/kvm/powerpc.c =20
> b/arch/powerpc/kvm/powerpc.c
> > >index 8465c2a..da6bf61 100644
> > >--- a/arch/powerpc/kvm/powerpc.c
> > >@@ -396,6 +396,7 @@ int kvm_dev_ioctl_check_extension(long ext)
> > >+++ b/arch/powerpc/kvm/powerpc.c
> > > break;
> > > #endif
> > > case KVM_CAP_SPAPR_MULTITCE:
> > >+ case KVM_CAP_SPAPR_TCE_IOMMU:
> > > r =3D 1;
> > > break;
> > > default:
> >
> > Don't advertise SPAPR capabilities if it's not book3s -- and
> > probably there's some additional limitation that would be
> > appropriate.
>=20
> So, in the case of MULTITCE, that's not quite right. PR KVM can
> emulate a PAPR system on a BookE machine, and there's no reason not to
> allow TCE acceleration as well.
That might (or might not; consider things like Altivec versus SPE =20
opcode conflict, whether unimplemented SPRs trap, behavior of =20
unprivileged SPRs/instructions, etc) be true in theory, but it's not =20
currently a supported configuration. BookE KVM does not support =20
emulating a different CPU than the host. In the unlikely case that =20
ever changes to the point of allowing PAPR guests on a BookE host, then =20
we can revisit how to properly determine whether the capability is =20
supported, but for now the capability will never be valid in the =20
CONFIG_BOOKE case (though I'd rather see it depend on an appropriate =20
book3s symbol than depend on !BOOKE).
Or we could just leave it as is, and let it indicate whether the host =20
kernel supports the feature in general, with the user needing to =20
understand when it's applicable... I'm a bit confused by the =20
documentation, however -- the MULTITCE capability was documented in the =20
"capabilities that can be enabled" section, but I don't see where it =20
can be enabled.
-Scott=
next prev parent reply other threads:[~2013-05-28 16:33 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-21 3:06 [PATCH 0/4 v2] KVM: PPC: IOMMU in-kernel handling Alexey Kardashevskiy
2013-05-21 3:06 ` [PATCH 1/4] KVM: PPC: Add support for multiple-TCE hcalls Alexey Kardashevskiy
2013-05-27 10:08 ` Paolo Bonzini
2013-05-27 14:33 ` Alexey Kardashevskiy
2013-05-21 3:06 ` [PATCH 2/4] powerpc: Prepare to support kernel handling of IOMMU map/unmap Alexey Kardashevskiy
2013-05-21 3:06 ` [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling Alexey Kardashevskiy
2013-05-22 21:06 ` Scott Wood
2013-05-25 2:45 ` David Gibson
2013-05-27 2:44 ` Alexey Kardashevskiy
2013-05-28 17:45 ` Scott Wood
2013-05-28 23:30 ` Alexey Kardashevskiy
2013-05-28 23:35 ` Scott Wood
2013-05-29 0:12 ` Alexey Kardashevskiy
2013-05-29 20:05 ` Scott Wood
2013-05-29 23:10 ` Alexey Kardashevskiy
2013-05-29 23:14 ` Scott Wood
2013-05-29 23:29 ` Alexey Kardashevskiy
2013-05-29 23:32 ` Scott Wood
2013-05-27 10:23 ` Paolo Bonzini
2013-05-27 14:26 ` Alexey Kardashevskiy
2013-05-27 14:41 ` Paolo Bonzini
2013-05-28 16:32 ` Scott Wood [this message]
2013-05-29 0:20 ` Alexey Kardashevskiy
2013-05-21 3:06 ` [PATCH 4/4] KVM: PPC: Add hugepage " Alexey Kardashevskiy
-- strict thread matches above, loose matches on Subject: below --
2013-06-05 6:11 [PATCH 0/4 v3] KVM: PPC: " Alexey Kardashevskiy
2013-06-05 6:11 ` [PATCH 3/4] KVM: PPC: Add support for " Alexey Kardashevskiy
2013-06-16 4:39 ` Benjamin Herrenschmidt
2013-06-19 3:17 ` Alexey Kardashevskiy
2013-06-16 22:25 ` Alexander Graf
2013-06-16 22:39 ` Benjamin Herrenschmidt
2013-06-17 3:13 ` Alex Williamson
2013-06-17 3:56 ` Benjamin Herrenschmidt
2013-06-18 2:32 ` Alex Williamson
2013-06-18 4:38 ` Benjamin Herrenschmidt
2013-06-18 14:48 ` Alex Williamson
2013-06-18 21:58 ` Benjamin Herrenschmidt
2013-06-19 3:35 ` Rusty Russell
2013-06-19 4:59 ` Benjamin Herrenschmidt
2013-06-19 9:58 ` Alexander Graf
2013-06-19 14:50 ` Benjamin Herrenschmidt
2013-06-19 15:49 ` Alex Williamson
2013-06-20 4:58 ` Alexey Kardashevskiy
2013-06-20 5:28 ` David Gibson
2013-06-20 7:47 ` Benjamin Herrenschmidt
2013-06-20 8:48 ` Alexey Kardashevskiy
2013-06-20 14:55 ` Alex Williamson
2013-06-22 8:25 ` Alexey Kardashevskiy
2013-06-22 12:03 ` David Gibson
2013-06-22 14:28 ` Alex Williamson
2013-06-24 3:52 ` David Gibson
2013-06-24 4:41 ` Alex Williamson
2013-06-27 11:01 ` David Gibson
2013-06-22 23:28 ` Benjamin Herrenschmidt
2013-06-24 3:54 ` David Gibson
2013-06-24 3:58 ` Benjamin Herrenschmidt
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