On Thu, Nov 30, 2017 at 04:43:00PM -0800, Feng Kan wrote: > On Wed, Nov 29, 2017 at 11:28 PM, Feng Kan <fkan@xxxxxxx> wrote: > > On Thu, Aug 3, 2017 at 5:32 AM, Lorenzo Pieralisi > > <lorenzo.pieralisi@xxxxxxx> 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(-) > >> > >> -- > >> 2.10.0 > >> > > Lorenzo: > > > > A network driver can use pci_set_dma_mask or its like to override what > > is done with this patch here. > > Which would result in iova allocation greater than the original _DMA > > aperture. Should we force > > the dma_set_mask to not change if an existing mask is already set? > > Let me clarify the question some more, in our system the IOMMU supports only > 42 bits of address. With your _DMA aperture patch, the initial dma_mask and > coherent_mask are correctly set by the code. However, the device driver can > set the dma_mask and coherent mask at a later point which over writes the > initial setting by your code. In which case, once the iova is exhausted with the > 32 bit address, it will start seeking more iova address via the > dma_limit. In this > case it would fail my system since the iommu.aperture_end is that of 48 bits > as derived from ias field in the SMMU. > > Should the dma_limit be the smallest of driver->dma_mask, iommu.aperture_end and > your _DMA aperture size via ACPI table? Rather than just the > driver->dma_mask and > iommu.aperture_end. This will ensure the smallest/correct aperture is used. IIUC Nate already reported this issue - I will sync with Robin to check the status of this thread: https://marc.info/?l=linux-acpi&m=150108156230455&w=2 Thanks, Lorenzo -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
