Hi,

Better late than never I guess..

On 08/03/2017 07:32 AM, Lorenzo Pieralisi wrote:
This patch series is v3 of a previous posting:

v2->v3:
        - Fixed DMA masks computation
         - Fixed size computation overflow in acpi_dma_get_range()

v1->v2:
        - Reworked acpi_dma_get_range() flow and logs
        - Added IORT named component address limits
        - Renamed acpi_dev_get_resources() helper function
        - Rebased against v4.13-rc3

v2: http://lkml.kernel.org/r/20170731152323.32488-1-lorenzo.pieral...@arm.com
v1: http://lkml.kernel.org/r/20170720144517.32529-1-lorenzo.pieral...@arm.com

-- Original cover letter --

As reported in:

http://lkml.kernel.org/r/cal85gma_sscwm80tkdkzqee+s1bewzdevdki1kpkmutdrms...@mail.gmail.com

the bus connecting devices to an IOMMU bus can be smaller in size than
the IOMMU input address bits which results in devices DMA HW bugs in
particular related to IOVA allocation (ie chopping of higher address
bits owing to system bus HW capabilities mismatch with the IOMMU).

Fortunately this problem can be solved through an already present but never
used ACPI 6.2 firmware bindings (ie _DMA object) allowing to define the DMA
window for a specific bus in ACPI and therefore all upstream devices
connected to it.

This small patch series enables _DMA parsing in ACPI core code and
use it in ACPI IORT code in order to detect DMA ranges for devices and
update their data structures to make them work with their related DMA
addressing restrictions.

Cc: Will Deacon <will.dea...@arm.com>
Cc: Hanjun Guo <hanjun....@linaro.org>
Cc: Feng Kan <f...@apm.com>
Cc: Jon Masters <j...@redhat.com>
Cc: Robert Moore <robert.mo...@intel.com>
Cc: Robin Murphy <robin.mur...@arm.com>
Cc: Zhang Rui <rui.zh...@intel.com>
Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>

Lorenzo Pieralisi (5):
   ACPICA: resource_mgr: Allow _DMA method in walk resources
   ACPI: Make acpi_dev_get_resources() method agnostic
   ACPI: Introduce DMA ranges parsing
   ACPI: Make acpi_dma_configure() DMA regions aware
   ACPI/IORT: Add IORT named component memory address limits

  drivers/acpi/acpica/rsxface.c |  7 ++--
  drivers/acpi/arm64/iort.c     | 57 ++++++++++++++++++++++++++-
  drivers/acpi/resource.c       | 82 +++++++++++++++++++++++++++++---------
  drivers/acpi/scan.c           | 91 +++++++++++++++++++++++++++++++++++++++----
  include/acpi/acnames.h        |  1 +
  include/acpi/acpi_bus.h       |  2 +
  include/linux/acpi.h          |  8 ++++
  include/linux/acpi_iort.h     |  5 ++-
  8 files changed, 219 insertions(+), 34 deletions(-)

Ok, despite being merged already I think its worthwhile to say that I've been testing this with:

Method(_DMA, 0, Serialized)
{
        Return (ResourceTemplate()
        {
                QWORDMemory(
                ResourceConsumer,
                PosDecode,          // _DEC
                MinFixed,           // _MIF
                MaxFixed,           // _MAF
                Prefetchable,       // _MEM
                ReadWrite,          // _RW
                0,                  // _GRA
                0x10000000,         // _MIN
                0x1fffffff,         // _MAX
                0x000000000,        // _TRA
                0x10000000,         // _LEN
                ,
                ,
                ,
                )
        })
} // Method(_DMA)

(and a couple minor variations)

and a fair number of debug statements sprinkled around to verify that the IOVAs are appropriately limited. So I don't see anything wrong with the code and it appears to work and the devices behind a bridge limited like this continue to work as long as sane values are placed in the min/max/len fields.

Thanks,

Tested-by: Jeremy Linton <jeremy.lin...@arm.com>

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