Hi Marc Zyngier, Mark Rutland; I'm looking forward to hear your feedback on this series. On 2/4/2016 11:34 PM, Sinan Kaya wrote: > The Qualcomm Technologies HIDMA device has been designed > to support virtualization technology. The driver has been > divided into two to follow the hardware design. > > 1. HIDMA Management driver > 2. HIDMA Channel driver > > Each HIDMA HW consists of multiple channels. These channels > share some set of common parameters. These parameters are > initialized by the management driver during power up. > Same management driver is used for monitoring the execution > of the channels. Management driver can change the performance > behavior dynamically such as bandwidth allocation and > prioritization in the future. > > The management driver is executed in host context and > is the main management entity for all channels provided by > the device. > > ------------------------ > What's new > ------------------------ > - Add back default number of descriptors. > - Fix compilation error in VFIO ACPI support. > - Merge the event-channel patch back to DTS and channel driver. > > ------------------------ > Git repos > ------------------------ > QEMU Support > https://www.codeaurora.org/cgit/quic/qemu/qemu/log/?h=v2.5.0-sriov > > ------------------------ > History of Changes > ------------------------ > dma: hidma: Add Device Tree Binding > Changes from V13: (https://lkml.org/lkml/2016/1/29/672) > * merged event-channel change. > > dma: add Qualcomm Technologies HIDMA channel driver > Changes from V13: (https://lkml.org/lkml/2016/1/29/685) > * add back default descriptor count > * merged event-channel change. > > dma: qcom_hidma: add support for object hierarchy > Changes from V13: (https://lkml.org/lkml/2016/1/29/680) > * initialize platform info data structure. > * configure DMA by calling of_dma_configure. DMA mask was not set when > * IOMMU driver is not present for the children devices. > > vfio, platform: add support for ACPI while detecting the reset driver > Changes from V13: (https://lkml.org/lkml/2016/1/29/679) > * add forgotten pointer during merge > * clarify the driver loading rules in commit message > > ------------------------ > FAQ > ------------------------ > - This doesn't seem to tie into KVM or VFIO, and as far as I can tell > there's no mechanism for associating channels with a particular virtual > address space (i.e. no configuration of an external or internal IOMMU), > nor pinning of guest pages to allow for DMA to occur safely. > > I'm using VFIO platform driver for this purpose. VFIO platform driver is > capable of assigning any platform device to a guest machine with this > driver. > > - Are there additional patches, or do you have some userspace that works > with this in some limited configuration? > > No, these are the only patches. We have one patch for the QEMU but from > kernel perspective this is it. I just rely on the platform VFIO driver > to do the work. > > - How do host and guest communicate, what is the infrastructure, how is > HIDMA meant to be used? > > They don't. Guest machine uses HIDMA channel driver to offload DMA > operations in isolation. The guest machine owns the HW registers for the > channel. It doesn't need to trap to host for register read/writes etc. > > All guest machine pages used are assumed to be pinned similar to VFIO > PCI. The reason is performance. The IOMMU takes care of the address > translation for me. > > - How do host and guest communicate? > They don't. > > - How is the integration performed in the hypervisor? > > Hypervisor has a bunch of channel resources. For each guest machine, the > channel gets unbound from the hypervisor. Channels get bind to each VFIO > platform device and then control is given to the guest machine. > > Once the guest machine is shutdown, VFIO driver still owns the channel > device. It can assign the device to another guest machine. > > - Does the HYP side requires any context switch (and how is that done)? > > No communication is needed. > > - What makes it safe? > No communication is needed. > > - Does the HYP side requires any context switch (and how is that done)? > > I don't believe this requires any context-switch -- it's the same as > assigning any other platform device other than additional proeprties > being controlled in the managament interface. > > - I'm concerned with how this is safe, and with the userspace interface. > e.g. if the user wants to up the QoS for a VM, how to they find the > right channel in sysfs to alter? > > The HW supports changing the QoS values on the flight. In order to > locate the object, I'm exporting a chid attribute in sysfs. > > Each management object has one priority and weight file per channel that > is indexed by the channel id read from the DMA object. > /sys/devices/platform/hidma-mgmt*/chanops/chan*/priority > /sys/devices/platform/QCOM8060:*/chanops/chan*/priority > > - So what is that hypervisor code used for? Is that your reset driver? > > The HIDMA "management" driver which runs at the hypervisor owns the > management HW. Management driver serves two purposes. > > 1. Common bus parameter configuration (could be called reset driver). > 2. Fine tuning the HW resources on the flight. > > Sinan Kaya (9): > dma: qcom_bam_dma: move to qcom directory > dma: hidma: Add Device Tree binding > dma: add Qualcomm Technologies HIDMA management driver > dma: add Qualcomm Technologies HIDMA channel driver > dma: qcom_hidma: implement lower level hardware interface > dma: qcom_hidma: add debugfs hooks > dma: qcom_hidma: add support for object hierarchy > vfio, platform: add support for ACPI while detecting the reset driver > vfio, platform: add QTI HIDMA reset driver > > Documentation/ABI/testing/sysfs-platform-hidma | 9 + > .../ABI/testing/sysfs-platform-hidma-mgmt | 97 +++ > .../devicetree/bindings/dma/qcom_hidma_mgmt.txt | 89 ++ > drivers/dma/Kconfig | 11 +- > drivers/dma/Makefile | 2 +- > drivers/dma/qcom/Kconfig | 29 + > drivers/dma/qcom/Makefile | 5 + > drivers/dma/{qcom_bam_dma.c => qcom/bam_dma.c} | 4 +- > drivers/dma/qcom/hidma.c | 746 +++++++++++++++++ > drivers/dma/qcom/hidma.h | 162 ++++ > drivers/dma/qcom/hidma_dbg.c | 219 +++++ > drivers/dma/qcom/hidma_ll.c | 927 +++++++++++++++++++++ > drivers/dma/qcom/hidma_mgmt.c | 407 +++++++++ > drivers/dma/qcom/hidma_mgmt.h | 39 + > drivers/dma/qcom/hidma_mgmt_sys.c | 295 +++++++ > drivers/vfio/platform/reset/Kconfig | 9 + > drivers/vfio/platform/reset/Makefile | 2 + > .../vfio/platform/reset/vfio_platform_amdxgbe.c | 3 +- > .../platform/reset/vfio_platform_calxedaxgmac.c | 3 +- > .../vfio/platform/reset/vfio_platform_qcomhidma.c | 99 +++ > drivers/vfio/platform/vfio_platform_common.c | 80 +- > drivers/vfio/platform/vfio_platform_private.h | 41 +- > 22 files changed, 3235 insertions(+), 43 deletions(-) > create mode 100644 Documentation/ABI/testing/sysfs-platform-hidma > create mode 100644 Documentation/ABI/testing/sysfs-platform-hidma-mgmt > create mode 100644 Documentation/devicetree/bindings/dma/qcom_hidma_mgmt.txt > create mode 100644 drivers/dma/qcom/Kconfig > create mode 100644 drivers/dma/qcom/Makefile > rename drivers/dma/{qcom_bam_dma.c => qcom/bam_dma.c} (99%) > create mode 100644 drivers/dma/qcom/hidma.c > create mode 100644 drivers/dma/qcom/hidma.h > create mode 100644 drivers/dma/qcom/hidma_dbg.c > create mode 100644 drivers/dma/qcom/hidma_ll.c > create mode 100644 drivers/dma/qcom/hidma_mgmt.c > create mode 100644 drivers/dma/qcom/hidma_mgmt.h > create mode 100644 drivers/dma/qcom/hidma_mgmt_sys.c > create mode 100644 drivers/vfio/platform/reset/vfio_platform_qcomhidma.c > -- Sinan Kaya Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc. 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