Re: [PATCH v4 0/3] PCIe Host request to reserve IOVA
From: Bjorn Helgaas
Date: Wed May 01 2019 - 08:55:52 EST
On Wed, May 01, 2019 at 12:30:38PM +0100, Lorenzo Pieralisi wrote:
> On Fri, Apr 12, 2019 at 08:43:32AM +0530, Srinath Mannam wrote:
> > Few SOCs have limitation that their PCIe host can't allow few inbound
> > address ranges. Allowed inbound address ranges are listed in dma-ranges
> > DT property and this address ranges are required to do IOVA mapping.
> > Remaining address ranges have to be reserved in IOVA mapping.
> > PCIe Host driver of those SOCs has to list resource entries of allowed
> > address ranges given in dma-ranges DT property in sorted order. This
> > sorted list of resources will be processed and reserve IOVA address for
> > inaccessible address holes while initializing IOMMU domain.
> > This patch set is based on Linux-5.0-rc2.
> > Changes from v3:
> > - Addressed Robin Murphy review comments.
> > - pcie-iproc: parse dma-ranges and make sorted resource list.
> > - dma-iommu: process list and reserve gaps between entries
> > Changes from v2:
> > - Patch set rebased to Linux-5.0-rc2
> > Changes from v1:
> > - Addressed Oza review comments.
> > Srinath Mannam (3):
> > PCI: Add dma_ranges window list
> > iommu/dma: Reserve IOVA for PCIe inaccessible DMA address
> > PCI: iproc: Add sorted dma ranges resource entries to host bridge
> > drivers/iommu/dma-iommu.c | 19 ++++++++++++++++
> > drivers/pci/controller/pcie-iproc.c | 44 ++++++++++++++++++++++++++++++++++++-
> > drivers/pci/probe.c | 3 +++
> > include/linux/pci.h | 1 +
> > 4 files changed, 66 insertions(+), 1 deletion(-)
> Bjorn, Joerg,
> this series should not affect anything in the mainline other than its
> consumer (ie patch 3); if that's the case should we consider it for v5.2
> and if yes how are we going to merge it ?
I acked the first one
Robin reviewed the second
(though I do agree with his comment about DMA_BIT_MASK()), Joerg was OK
with it if Robin was
Eric reviewed the third (and pointed out a typo).
My Kconfiggery never got fully answered -- it looks to me as though it's
possible to build pcie-iproc without the DMA hole support, and I thought
the whole point of this series was to deal with those holes
(https://lore.kernel.org/lkml/20190418234241.GF126710@xxxxxxxxxx). I would
have expected something like making pcie-iproc depend on IOMMU_SUPPORT.
But Srinath didn't respond to that, so maybe it's not an issue and it
should only affect pcie-iproc anyway.
So bottom line, I'm fine with merging it for v5.2. Do you want to merge
it, Lorenzo, or ...?