Re: [PATCH kernel RFC 0/4] powerpc/powenv/ioda: Allow huge DMA window at 4GB

From: David Gibson <david@gibson.dropbear.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
	Alistair Popple <alistair@popple.id.au>,
	Alex Williamson <alex.williamson@redhat.com>,
	Oliver O'Halloran <oohall@gmail.com>
Subject: Re: [PATCH kernel RFC 0/4] powerpc/powenv/ioda: Allow huge DMA window at 4GB
Date: Thu, 23 Jan 2020 12:17:30 +1100
Message-ID: <20200123011730.GL2347@umbus.fritz.box> (raw)
In-Reply-To: <9423b5e0-75e9-4a7a-7e65-818879d52d48@ozlabs.ru>

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On Thu, Jan 23, 2020 at 11:53:32AM +1100, Alexey Kardashevskiy wrote:
> Anyone, ping?

Sorry, I've totally lost track of this one.  I think you'll need to
repost.

> 
> 
> On 10/01/2020 15:18, Alexey Kardashevskiy wrote:
> > 
> > 
> > On 02/12/2019 12:59, Alexey Kardashevskiy wrote:
> >> Here is an attempt to support bigger DMA space for devices
> >> supporting DMA masks less than 59 bits (GPUs come into mind
> >> first). POWER9 PHBs have an option to map 2 windows at 0
> >> and select a windows based on DMA address being below or above
> >> 4GB.
> >>
> >> This adds the "iommu=iommu_bypass" kernel parameter and
> >> supports VFIO+pseries machine - current this requires telling
> >> upstream+unmodified QEMU about this via
> >> -global spapr-pci-host-bridge.dma64_win_addr=0x100000000
> >> or per-phb property. 4/4 advertises the new option but
> >> there is no automation around it in QEMU (should it be?).
> >>
> >> For now it is either 1<<59 or 4GB mode; dynamic switching is
> >> not supported (could be via sysfs).
> >>
> >> This is based on sha1
> >> a6ed68d6468b Linus Torvalds "Merge tag 'drm-next-2019-11-27' of git://anongit.freedesktop.org/drm/drm".
> >>
> >> Please comment. Thanks.
> > 
> > 
> > David, Alistair, ping? Thanks,
> 
> 
> > 
> > 
> >>
> >>
> >>
> >> Alexey Kardashevskiy (4):
> >>   powerpc/powernv/ioda: Rework for huge DMA window at 4GB
> >>   powerpc/powernv/ioda: Allow smaller TCE table levels
> >>   powerpc/powernv/phb4: Add 4GB IOMMU bypass mode
> >>   vfio/spapr_tce: Advertise and allow a huge DMA windows at 4GB
> >>
> >>  arch/powerpc/include/asm/iommu.h              |   1 +
> >>  arch/powerpc/include/asm/opal-api.h           |  11 +-
> >>  arch/powerpc/include/asm/opal.h               |   2 +
> >>  arch/powerpc/platforms/powernv/pci.h          |   1 +
> >>  include/uapi/linux/vfio.h                     |   2 +
> >>  arch/powerpc/platforms/powernv/opal-call.c    |   2 +
> >>  arch/powerpc/platforms/powernv/pci-ioda-tce.c |   4 +-
> >>  arch/powerpc/platforms/powernv/pci-ioda.c     | 219 ++++++++++++++----
> >>  drivers/vfio/vfio_iommu_spapr_tce.c           |  10 +-
> >>  9 files changed, 202 insertions(+), 50 deletions(-)
> >>
> > 
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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