Re: [PATCH V11 08/11] drivers: acpi: Handle IOMMU lookup failure with deferred probing or error

[Nate Watterson]

Hi Lorenzo,

On 5/23/2017 5:26 AM, Lorenzo Pieralisi wrote:
> On Tue, May 23, 2017 at 02:31:17PM +0530, Sricharan R wrote:
> > Hi Lorenzo,
> >
> > On 5/23/2017 2:22 PM, Lorenzo Pieralisi wrote:
> > > On Tue, May 23, 2017 at 02:26:10AM -0400, Nate Watterson wrote:
> > > > Hi Sricharan,
> > > >
> > > > On 4/10/2017 7:21 AM, Sricharan R wrote:
> > > > > This is an equivalent to the DT's handling of the iommu master's probe
> > > > > with deferred probing when the corrsponding iommu is not probed yet.
> > > > > The lack of a registered IOMMU can be caused by the lack of a driver for
> > > > > the IOMMU, the IOMMU device probe not having been performed yet, having
> > > > > been deferred, or having failed.
> > > > >
> > > > > The first case occurs when the firmware describes the bus master and
> > > > > IOMMU topology correctly but no device driver exists for the IOMMU yet
> > > > > or the device driver has not been compiled in. Return NULL, the caller
> > > > > will configure the device without an IOMMU.
> > > > >
> > > > > The second and third cases are handled by deferring the probe of the bus
> > > > > master device which will eventually get reprobed after the IOMMU.
> > > > >
> > > > > The last case is currently handled by deferring the probe of the bus
> > > > > master device as well. A mechanism to either configure the bus master
> > > > > device without an IOMMU or to fail the bus master device probe depending
> > > > > on whether the IOMMU is optional or mandatory would be a good
> > > > > enhancement.
> > > > >
> > > > > Tested-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> > > > > Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
> > > > > [Lorenzo: Added fixes for dma_coherent_mask overflow, acpi_dma_configure
> > > > >            called multiple times for same device]
> > > > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > > > > Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx>
> > > > > ---
> > > > >   drivers/acpi/arm64/iort.c  | 33 ++++++++++++++++++++++++++++++++-
> > > > >   drivers/acpi/scan.c        | 11 ++++++++---
> > > > >   drivers/base/dma-mapping.c |  2 +-
> > > > >   include/acpi/acpi_bus.h    |  2 +-
> > > > >   include/linux/acpi.h       |  7 +++++--
> > > > >   5 files changed, 47 insertions(+), 8 deletions(-)
> > > > >
> > > > > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> > > > > index 3dd9ec3..e323ece 100644
> > > > > --- a/drivers/acpi/arm64/iort.c
> > > > > +++ b/drivers/acpi/arm64/iort.c
> > > > > @@ -543,6 +543,14 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
> > > > >   	const struct iommu_ops *ops = NULL;
> > > > >   	int ret = -ENODEV;
> > > > >   	struct fwnode_handle *iort_fwnode;
> > > > > +	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> > > > > +
> > > > > +	/*
> > > > > +	 * If we already translated the fwspec there
> > > > > +	 * is nothing left to do, return the iommu_ops.
> > > > > +	 */
> > > > > +	if (fwspec && fwspec->ops)
> > > > > +		return fwspec->ops;
> > > >
> > > > Is this logic strictly required? It breaks masters with multiple SIDs
> > > > as only the first SID is actually added to the master's fwspec.
> > >
> > > My bad, that's indeed a silly bug I introduced. Please let me know if the
> > > patch below fixes it, we will send it upstream shortly.
> >
> > oops, i think emails crossed. Please let me know if you are ok to add
> > this to the other fixes.
>
> No worries, yes I am ok thanks but please give Nate some time to report
> back to make sure the diff I sent actually fixes the problem.

The patch you sent fixes the problem. Thanks for the quick turnaround.

> Apologies for the breakage.
>
> Lorenzo
>
> > Regards,
> >   Sricharan

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