Re: [PATCH v3 0/5] ACPI: DMA ranges management
From: Robin Murphy
Date: Thu Aug 03 2017 - 13:21:43 EST
On 03/08/17 16:45, Nate Watterson wrote:
> Hi Lorenzo,
>
> On 8/3/2017 8:32 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.pieralisi@xxxxxxx
>> v1:
>> http://lkml.kernel.org/r/20170720144517.32529-1-lorenzo.pieralisi@xxxxxxx
>>
>> -- Original cover letter --
>>
>> As reported in:
>>
>> http://lkml.kernel.org/r/CAL85gmA_SSCwM80TKdkZqEe+S1beWzDEvdki1kpkmUTDRmSP7g@xxxxxxxxxxxxxx
>>
>>
>> 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.deacon@xxxxxxx>
>> Cc: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
>> Cc: Feng Kan <fkan@xxxxxxx>
>> Cc: Jon Masters <jcm@xxxxxxxxxx>
>> Cc: Robert Moore <robert.moore@xxxxxxxxx>
>> Cc: Robin Murphy <robin.murphy@xxxxxxx>
>> Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
>> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
>>
>> 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(-)
>>
>
> I tested with named components and with _DMA objects at a variety of
> sizes and verified the configured masks matched the expected values.
>
> Tested-by: Nate Watterson <nwatters@xxxxxxxxxxxxxx>
>
> One general question I had while testing the patch is whether it is
> possible to define a complete 64-bit range using the _DMA method. For
> instance, to get a 64-bit dma_mask I had to use a non-zero MIN value
> so that LEN would not overflow.
As far as I understand ACPI, all addresses are at most 64-bit. Thus the
only valid DMA range of size 2^64 would be one with a minimum of 0 and
no offset, and that can already be described by the simple absence of a
_DMA object.
Robin.
>
> QWORDMemory(
> ResourceConsumer,
> PosDecode, // _DEC
> MinFixed, // _MIF
> MaxFixed, // _MAF
> Prefetchable, // _MEM
> ReadWrite, // _RW
> 0, // _GRA
> 0x1000, // _MIN
> 0xffffffffffffffff, // _MAX
> 0x0, // _TRA
> 0xfffffffffffff000, // _LEN
> ,
> ,
> ,
> )
>
> -Nate
>