Re: [PATCH 00/83] AMD HSA kernel driver

From: Christian König
Date: Sat Jul 12 2014 - 05:25:11 EST

Am 11.07.2014 23:18, schrieb Jerome Glisse:
On Thu, Jul 10, 2014 at 10:51:29PM +0000, Gabbay, Oded wrote:
On Thu, 2014-07-10 at 18:24 -0400, Jerome Glisse wrote:
On Fri, Jul 11, 2014 at 12:45:27AM +0300, Oded Gabbay wrote:
This patch set implements a Heterogeneous System Architecture
(HSA) driver
for radeon-family GPUs.
This is just quick comments on few things. Given size of this, people
will need to have time to review things.
HSA allows different processor types (CPUs, DSPs, GPUs, etc..) to
system resources more effectively via HW features including
shared pageable
memory, userspace-accessible work queues, and platform-level
atomics. In
addition to the memory protection mechanisms in GPUVM and
IOMMUv2, the Sea
Islands family of GPUs also performs HW-level validation of
commands passed
in through the queues (aka rings).
The code in this patch set is intended to serve both as a sample
driver for
other HSA-compatible hardware devices and as a production driver
radeon-family processors. The code is architected to support
multiple CPUs
each with connected GPUs, although the current implementation
focuses on a
single Kaveri/Berlin APU, and works alongside the existing radeon
graphics driver (kgd).
AMD GPUs designed for use with HSA (Sea Islands and up) share
some hardware
functionality between HSA compute and regular gfx/compute (memory,
interrupts, registers), while other functionality has been added
specifically for HSA compute (hw scheduler for virtualized
compute rings).
All shared hardware is owned by the radeon graphics driver, and
an interface
between kfd and kgd allows the kfd to make use of those shared
while HSA-specific functionality is managed directly by kfd by
packets into an HSA-specific command queue (the "HIQ").
During kfd module initialization a char device node (/dev/kfd) is
(surviving until module exit), with ioctls for queue creation &
and data structures are initialized for managing HSA device
The rest of the initialization is driven by calls from the radeon
kgd at
the following points :
- radeon_init (kfd_init)
- radeon_exit (kfd_fini)
- radeon_driver_load_kms (kfd_device_probe, kfd_device_init)
- radeon_driver_unload_kms (kfd_device_fini)
During the probe and init processing per-device data structures
established which connect to the associated graphics kernel
driver. This
information is exposed to userspace via sysfs, along with a
version number
allowing userspace to determine if a topology change has occurred
while it
was reading from sysfs.
The interface between kfd and kgd also allows the kfd to request
management services from kgd, and allows kgd to route interrupt
requests to
kfd code since the interrupt block is shared between regular
graphics/compute and HSA compute subsystems in the GPU.
The kfd code works with an open source usermode library
("libhsakmt") which
is in the final stages of IP review and should be published in a
repo over the next few days.
The code operates in one of three modes, selectable via the
module parameter :
- sched_policy=0 uses a hardware scheduler running in the MEC
block within
CP, and allows oversubscription (more queues than HW slots)
- sched_policy=1 also uses HW scheduling but does not allow
oversubscription, so create_queue requests fail when we run out
of HW slots
- sched_policy=2 does not use HW scheduling, so the driver
manually assigns
queues to HW slots by programming registers
The "no HW scheduling" option is for debug & new hardware bringup
only, so
has less test coverage than the other options. Default in the
current code
is "HW scheduling without oversubscription" since that is where
we have the
most test coverage but we expect to change the default to "HW
with oversubscription" after further testing. This effectively
removes the
HW limit on the number of work queues available to applications.
Programs running on the GPU are associated with an address space
through the
VMID field, which is translated to a unique PASID at access time
via a set
of 16 VMID-to-PASID mapping registers. The available VMIDs
(currently 16)
are partitioned (under control of the radeon kgd) between current
gfx/compute and HSA compute, with each getting 8 in the current
code. The
VMID-to-PASID mapping registers are updated by the HW scheduler
when used,
and by driver code if HW scheduling is not being used.
The Sea Islands compute queues use a new "doorbell" mechanism
instead of the
earlier kernel-managed write pointer registers. Doorbells use a
separate BAR
dedicated for this purpose, and pages within the doorbell
aperture are
mapped to userspace (each page mapped to only one user address
Writes to the doorbell aperture are intercepted by GPU hardware,
userspace code to safely manage work queues (rings) without
requiring a
kernel call for every ring update.
First step for an application process is to open the kfd device.
Calls to
open create a kfd "process" structure only for the first thread
of the
process. Subsequent open calls are checked to see if they are
from processes
using the same mm_struct and, if so, don't do anything. The kfd
data lives as long as the mm_struct exists. Each mm_struct is
with a unique PASID, allowing the IOMMUv2 to make userspace
process memory
accessible to the GPU.
Next step is for the application to collect topology information
via sysfs.
This gives userspace enough information to be able to identify
nodes (processors) in subsequent queue management calls.
processes can create queues on multiple processors, and
processors support
queues from multiple processes.
I am not a fan to use sysfs to discover topoly.
At this point the application can create work queues in userspace
memory and
pass them through the usermode library to kfd to have them mapped
onto HW
queue slots so that commands written to the queues can be
executed by the
GPU. Queue operations specify a processor node, and so the bulk
of this code
is device-specific.
Written by John Bridgman <John.Bridgman@xxxxxxx>
So general comment is you need to collapse many patches things like
58 fixing
kernel style should be collapsed ie fix all previous patch that have
Even worse is thing like 71, removing code you just added few patch
in the patchset.
Not quite, the code was added on patch 11.

This means that if i start reviewing following
patch order
i might spend time on code that is later deleted/modified/fixed ie
time i
spend understanding and reading some code might be just wasted.
Quick answer is that you are of course right, but having said that, I
think it would be not simple at all to do that squashing.
I squashed what I could, and probably I can do a little more (like
58), but the major problem is that one of the main modules of the
driver - the scheduler (QCM) - was completely re-written (patches
46-53). Therefore, from patch 1 to 53, we use the old scheduler code
and from 54 we use the new QCM (and the old scheduler code was
completely remove at 71). So I could maybe squash 71 into 54, but that
won't help you much, I think.

So, the current advice I can give is to completely ignore the
following files because they do not exist in the final commit:
- kfd_sched_cik_static.c (stopped using in 54)
- kfd_registers.c (stopped using in 81 because we moved all register
writes to radeon)
- kfd_hw_pointer_store.c (alive from 46 to 67)
- kfd_hw_pointer_store.h (alive from 46 to 67)

Ok i try but this is driving me crazy, i am jungling btw full applied
patchset and individual patch going back and forth trying to find which
patch is the one i want to comment on. Not even mentioning that after
that people would need to ack bad patch just because they know a latter
good patch fix the badness.

This patchset can be reduced to less then 10 big patches. I would first
do core patches that touch core things like iommu and are preparatory
to the patchset. Then kfd patches that do not touch anything in radeon
but implement the skeleton and core infrastructure. Then radeon specific

This lead me to the design, all the core kfd helper should be in hsa
directory, and should be helper, while all specific bits to radeon
should most likely be part of the radeon gfx kernel module. I am not
against a radeon_kfd but realy i do not see the point. There should
be a hsa.ko like there is a drm.ko.

Yeah totally agree with Jerome here.

Maybe I can explain a bit further what the difference in the design is. First of all for other good examples see not only the DRM infrastructure, but also V4L or other Linux driver subsystems as well.

In those subsystems it's not the helper functions that control the driver, but instead the driver that controls the helper functions. E.g. if HSA wants to be a new subsystem with a standardized IOCTL interface it should provide functions that assists drivers with implementing the interface instead of implementing it themselves and then trying to talk to the drivers for necessary resources/operations.

Coming back to the structure of the patches one of the very first patches should be the IOCTL definition a driver needs to implement to be HSA conform.

I think it would be a good idea to split out changes to core structures like IOMMU in it's own separately submitted patches, only with the notice that this functionality is needed by the following "core HSA" and "HSA for radeon" patchsets.


Also i think it would be benefical to rename kfd to hsa because it is
the most common name and the name that will bring valid hit with web

Each of the patch should have a proper commit message that is not too
cryptic without being too chatty either.


I will come back with individual patch comments and also general
Alexey Skidanov (4):
hsa/radeon: 32-bit processes support
hsa/radeon: NULL pointer dereference bug workaround
hsa/radeon: HSA64/HSA32 modes support
hsa/radeon: Add local memory to topology
Andrew Lewycky (3):
hsa/radeon: Make binding of process to device permanent
hsa/radeon: Implement hsaKmtSetMemoryPolicy
mm: Change timing of notification to IOMMUs about a page to be
Ben Goz (20):
hsa/radeon: Add queue and hw_pointer_store modules
hsa/radeon: Add support allocating kernel doorbells
hsa/radeon: Add mqd_manager module
hsa/radeon: Add kernel queue support for KFD
hsa/radeon: Add module parameter of scheduling policy
hsa/radeon: Add packet manager module
hsa/radeon: Add process queue manager module
hsa/radeon: Add device queue manager module
hsa/radeon: Switch to new queue scheduler
hsa/radeon: Add IOCTL for update queue
hsa/radeon: Queue Management integration with Memory Management
hsa/radeon: update queue fault handling
hsa/radeon: fixing a bug to support 32b processes
hsa/radeon: Fix number of pipes per ME
hsa/radeon: Removing hw pointer store module
hsa/radeon: Adding some error messages
hsa/radeon: Fixing minor issues with kernel queues (DIQ)
drm/radeon: Add register access functions to kfd2kgd interface
hsa/radeon: Eliminating all direct register accesses
drm/radeon: Remove lock functions from kfd2kgd interface
Evgeny Pinchuk (9):
hsa/radeon: fix the OEMID assignment in kfd_topology
drm/radeon: extending kfd-kgd interface
hsa/radeon: implementing IOCTL for clock counters
drm/radeon: adding synchronization for GRBM GFX
hsa/radeon: fixing clock counters bug
drm/radeon: Extending kfd interface
hsa/radeon: Adding max clock speeds to topology
hsa/radeon: Alternating the source of max clock
hsa/radeon: Exclusive access for perf. counters
Michael Varga (1):
hsa/radeon: debugging print statements
Oded Gabbay (45):
mm: Add kfd_process pointer to mm_struct
drm/radeon: reduce number of free VMIDs and pipes in KV
drm/radeon: Report doorbell configuration to kfd
drm/radeon: Add radeon <--> kfd interface
drm/radeon: Add kfd-->kgd interface to get virtual ram size
drm/radeon: Add kfd-->kgd interfaces of memory
drm/radeon: Add kfd-->kgd interface of locking srbm_gfx_cntl
drm/radeon: Add calls to initialize and finalize kfd from radeon
hsa/radeon: Add code base of hsa driver for AMD's GPUs
hsa/radeon: Add initialization and unmapping of doorbell
hsa/radeon: Add scheduler code
hsa/radeon: Add kfd mmap handler
hsa/radeon: Add 2 new IOCTL to kfd, CREATE_QUEUE and
hsa/radeon: Update MAINTAINERS and CREDITS files
hsa/radeon: Add interrupt handling module
hsa/radeon: Add the isr function of the KFD scehduler
hsa/radeon: Handle deactivation of queues using interrupts
hsa/radeon: Enable interrupts in KFD scheduler
hsa/radeon: Enable/Disable KFD interrupt module
hsa/radeon: Add interrupt callback function to kgd2kfd interface
hsa/radeon: Add kgd-->kfd interfaces for suspend and resume
drm/radeon: Add calls to suspend and resume of kfd driver
drm/radeon/cik: Don't touch int of pipes 1-7
drm/radeon/cik: Call kfd isr function
hsa/radeon: Fix memory size allocated for HPD
hsa/radeon: Fix list of supported devices
hsa/radeon: Fix coding style in cik_int.h
hsa/radeon: Print ioctl commnad only in debug mode
hsa/radeon: Print ISR info only in debug mode
hsa/radeon: Workaround for a bug in amd_iommu
hsa/radeon: Eliminate warnings in compilation
hsa/radeon: Various kernel styling fixes
hsa/radeon: Rearrange structures in kfd_ioctl.h
hsa/radeon: change another pr_info to pr_debug
hsa/radeon: Fix timeout calculation in sync_with_hw
hsa/radeon: Update module information and version
hsa/radeon: Update module version to 0.6.0
hsa/radeon: Fix initialization of sh_mem registers
hsa/radeon: Fix compilation warnings
hsa/radeon: Remove old scheduler code
hsa/radeon: Static analysis (smatch) fixes
hsa/radeon: Check oversubscription before destroying runlist
hsa/radeon: Don't verify cksum when parsing CRAT table
hsa/radeon: Update module version to 0.6.1
hsa/radeon: Update module version to 0.6.2
Yair Shachar (1):
hsa/radeon: Adding qcm fence return status
drivers/Kconfig | 2 +
drivers/gpu/Makefile | 1 +
drivers/gpu/drm/radeon/Makefile | 1 +
drivers/gpu/drm/radeon/cik.c | 156 +--
drivers/gpu/drm/radeon/cikd.h | 51 +-
drivers/gpu/drm/radeon/radeon.h | 9 +
drivers/gpu/drm/radeon/radeon_device.c | 32 +
drivers/gpu/drm/radeon/radeon_drv.c | 6 +
drivers/gpu/drm/radeon/radeon_kfd.c | 630
drivers/gpu/drm/radeon/radeon_kms.c | 9 +
drivers/gpu/hsa/Kconfig | 20 +
drivers/gpu/hsa/Makefile | 1 +
drivers/gpu/hsa/radeon/Makefile | 12 +
drivers/gpu/hsa/radeon/cik_int.h | 50 +
drivers/gpu/hsa/radeon/cik_mqds.h | 250 ++++
drivers/gpu/hsa/radeon/cik_regs.h | 220 ++++
drivers/gpu/hsa/radeon/kfd_aperture.c | 123 ++
drivers/gpu/hsa/radeon/kfd_chardev.c | 530
drivers/gpu/hsa/radeon/kfd_crat.h | 294 +++++
drivers/gpu/hsa/radeon/kfd_device.c | 244 ++++
drivers/gpu/hsa/radeon/kfd_device_queue_manager.c | 981
drivers/gpu/hsa/radeon/kfd_device_queue_manager.h | 101 ++
drivers/gpu/hsa/radeon/kfd_doorbell.c | 242 ++++
drivers/gpu/hsa/radeon/kfd_interrupt.c | 177 +++
drivers/gpu/hsa/radeon/kfd_kernel_queue.c | 305 +++++
drivers/gpu/hsa/radeon/kfd_kernel_queue.h | 66 ++
drivers/gpu/hsa/radeon/kfd_module.c | 130 +++
drivers/gpu/hsa/radeon/kfd_mqd_manager.c | 290 +++++
drivers/gpu/hsa/radeon/kfd_mqd_manager.h | 54 +
drivers/gpu/hsa/radeon/kfd_packet_manager.c | 488
drivers/gpu/hsa/radeon/kfd_pasid.c | 97 ++
drivers/gpu/hsa/radeon/kfd_pm4_headers.h | 682
drivers/gpu/hsa/radeon/kfd_pm4_opcodes.h | 107 ++
drivers/gpu/hsa/radeon/kfd_priv.h | 475
drivers/gpu/hsa/radeon/kfd_process.c | 391 +++++++
drivers/gpu/hsa/radeon/kfd_process_queue_manager.c | 343 ++++++
drivers/gpu/hsa/radeon/kfd_queue.c | 109 ++
drivers/gpu/hsa/radeon/kfd_scheduler.h | 72 ++
drivers/gpu/hsa/radeon/kfd_topology.c | 1207
drivers/gpu/hsa/radeon/kfd_topology.h | 168 +++
drivers/gpu/hsa/radeon/kfd_vidmem.c | 97 ++
include/linux/mm_types.h | 14 +
include/linux/radeon_kfd.h | 106 ++
include/uapi/linux/kfd_ioctl.h | 133 +++
mm/rmap.c | 8 +-
47 files changed, 9402 insertions(+), 97 deletions(-)
create mode 100644 drivers/gpu/drm/radeon/radeon_kfd.c
create mode 100644 drivers/gpu/hsa/Kconfig
create mode 100644 drivers/gpu/hsa/Makefile
create mode 100644 drivers/gpu/hsa/radeon/Makefile
create mode 100644 drivers/gpu/hsa/radeon/cik_int.h
create mode 100644 drivers/gpu/hsa/radeon/cik_mqds.h
create mode 100644 drivers/gpu/hsa/radeon/cik_regs.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_aperture.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_chardev.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_crat.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_device.c
create mode 100644
create mode 100644
create mode 100644 drivers/gpu/hsa/radeon/kfd_doorbell.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_interrupt.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_kernel_queue.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_kernel_queue.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_module.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_mqd_manager.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_mqd_manager.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_packet_manager.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_pasid.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_pm4_headers.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_pm4_opcodes.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_priv.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_process.c
create mode 100644
create mode 100644 drivers/gpu/hsa/radeon/kfd_queue.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_scheduler.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_topology.c
create mode 100644 drivers/gpu/hsa/radeon/kfd_topology.h
create mode 100644 drivers/gpu/hsa/radeon/kfd_vidmem.c
create mode 100644 include/linux/radeon_kfd.h
create mode 100644 include/uapi/linux/kfd_ioctl.h
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