This adds an afu_driver_ops structure with fetch_event() and
event_delivered() callbacks. An AFU driver such as cxlflash can fill
this out and associate it with a context to enable passing custom AFU
specific events to userspace.
This also adds a new kernel API function cxl_context_pending_events(),
that the AFU driver can use to notify the cxl driver that new specific
events are ready to be delivered, and wake up anyone waiting on the
context wait queue.
The current count of AFU driver specific events is stored in the field
afu_driver_events of the context structure.
The cxl driver checks the afu_driver_events count during poll, select,
read, etc. calls to check if an AFU driver specific event is pending,
and calls fetch_event() to obtain and deliver that event. This way, the
cxl driver takes care of all the usual locking semantics around these
calls and handles all the generic cxl events, so that the AFU driver
only needs to worry about it's own events.
fetch_event() return a struct cxl_event_afu_driver_reserved, allocated
by the AFU driver, and filled in with the specific event information and
size. Total event size (header + data) should not be greater than
CXL_READ_MIN_SIZE (4K).
Th cxl driver prepends an appropriate cxl event header, copies the event
to userspace, and finally calls event_delivered() to return the status of
the operation to the AFU driver. The event is identified by the context
and cxl_event_afu_driver_reserved pointers.
Since AFU drivers provide their own means for userspace to obtain the
AFU file descriptor (i.e. cxlflash uses an ioctl on their scsi file
descriptor to obtain the AFU file descriptor) and the generic cxl driver
will never use this event, the ABI of the event is up to each individual
AFU driver.
Signed-off-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The new flash.c file contains the logic to flash a new image on the
adapter, through a hcall. It is an iterative process, with chunks of
data of 1M at a time. There are also 2 phases: write and verify. The
flash operation itself is driven from a user-land tool.
Once flashing is successful, an rtas call is made to update the device
tree with the new properties values for the adapter and the AFU(s)
Add a new char device for the adapter, so that the flash tool can
access the card, even if there is no valid AFU on it.
Co-authored-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Manoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
userspace programs using cxl currently have to use two strategies for
dealing with MMIO errors simultaneously. They have to check every read
for a return of all Fs in case the adapter has gone away and the kernel
has not yet noticed, and they have to deal with SIGBUS in case the
kernel has already noticed, invalidated the mapping and marked the
context as failed.
In order to simplify things, this patch adds an alternative approach
where the kernel will return a page filled with Fs instead of delivering
a SIGBUS. This allows userspace to only need to deal with one of these
two error paths, and is intended for use in libraries that use cxl
transparently and may not be able to safely install a signal handler.
This approach will only work if certain constraints are met. Namely, if
the application is both reading and writing to an address in the problem
state area it cannot assume that a non-FF read is OK, as it may just be
reading out a value it has previously written. Further - since only one
page is used per context a write to a given offset would be visible when
reading the same offset from a different page in the mapping (this only
applies within a single context, not between contexts).
An application could deal with this by e.g. making sure it also reads
from a read-only offset after any reads to a read/write offset.
Due to these constraints, this functionality must be explicitly
requested by userspace when starting the context by passing in the
CXL_START_WORK_ERR_FF flag.
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Given a file descriptor on an afu device, libcxl currently uses the
major/minor number obtained from fstat on the fd to construct path to
the afu's sysfs directory. However it is possible that rather than using
one of the device in /dev/cxl, a kernel driver creates its own device
which export generic cxl interface to the userspace. This causes
problems with libcxl as it tries to use a wrong major/minor number to
construct the sysfs path and fail.
So this patch introduces a new ioctl called CXL_IOCTL_GET_AFU_ID on the
afu file descriptor to fetch the cxl_afu_id struct that holds the
card/offset-id and mode information. These info is then used by libcxl to
construct the correct path to the afu sysfs directory.
Testing:
- Build against pseries be/le configs
- Testing with corresponding libcxl changes to verify that it constructs
right sysfs path to the afu.
Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This documentation gives an overview of the hardware architecture, userspace
APIs via /dev/cxl/afuM.N and the syfs files. It also adds a MAINTAINERS file
entry for cxl.
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This adds a header file for use by userspace programs wanting to interact with
the kernel cxl driver. It defines structs and magic numbers required for
userspace to interact with devices in /dev/cxl/afuM.N.
Further documentation on this interface is added in a subsequent patch in
Documentation/powerpc/cxl.txt.
It also adds this new userspace header file to Kbuild so it's exported when
doing "make headers_installs".
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Philippe Bergheaud