linux-stable.git/drivers/misc/cxl/api.c, branch linux-4.6.y

cxl: Remove cxl_get_phys_dev() kernel API

2016-03-09T12:40:02+00:00

The cxl_get_phys_dev() API returns a struct device pointer which could
belong to either a struct pci_dev (bare-metal) or platform_device
(powerVM). To avoid potential problems in drivers, remove that API. It
was introduced to allow drivers to read the VPD of the adapter, but
the cxl driver now provides the cxl_pci_read_adapter_vpd() API for
that purpose.

Co-authored-by: Christophe Lombard 
Signed-off-by: Frederic Barrat 
Signed-off-by: Christophe Lombard 
Acked-by: Ian Munsie 
Signed-off-by: Michael Ellerman

cxl: Support the cxl kernel API from a guest

2016-03-09T12:40:00+00:00

Like on bare-metal, the cxl driver creates a virtual PHB and a pci
device for the AFU. The configuration space of the device is mapped to
the configuration record of the AFU.

Reuse the code defined in afu_cr_read8|16|32() when reading the
configuration space of the AFU device.

Even though the (virtual) AFU device is a pci device, the adapter is
not. So a driver using the cxl kernel API cannot read the VPD of the
adapter through the usual PCI interface. Therefore, we add a call to
the cxl kernel API:
ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count);

Co-authored-by: Christophe Lombard 
Signed-off-by: Frederic Barrat 
Signed-off-by: Christophe Lombard 
Reviewed-by: Manoj Kumar 
Acked-by: Ian Munsie 
Signed-off-by: Michael Ellerman

cxl: Add guest-specific code

2016-03-09T12:36:52+00:00

The new of.c file contains code to parse the device tree to find out
about cxl adapters and AFUs.

guest.c implements the guest-specific callbacks for the backend API.

The process element ID is not known until the context is attached, so
we have to separate the context ID assigned by the cxl driver from the
process element ID visible to the user applications. In bare-metal,
the 2 IDs match.

Co-authored-by: Frederic Barrat 
Signed-off-by: Frederic Barrat 
Signed-off-by: Christophe Lombard 
Reviewed-by: Manoj Kumar 
Acked-by: Ian Munsie 
[mpe: Fix SMP=n build, fix PSERIES=n build, minor whitespace fixes]
Signed-off-by: Michael Ellerman

cxl: Introduce implementation-specific API

2016-03-09T02:05:43+00:00

The backend API (in cxl.h) lists some low-level functions whose
implementation is different on bare-metal and in a guest. Each
environment implements its own functions, and the common code uses
them through function pointers, defined in cxl_backend_ops

Co-authored-by: Christophe Lombard 
Signed-off-by: Frederic Barrat 
Signed-off-by: Christophe Lombard 
Reviewed-by: Manoj Kumar 
Acked-by: Ian Munsie 
Signed-off-by: Michael Ellerman

cxl: Define process problem state area at attach time only

2016-03-09T02:05:41+00:00

CXL kernel API was defining the process problem state area during
context initialization, making it possible to map the problem state
area before attaching the context. This won't work on a powerVM
guest. So force the logical behavior, like in userspace: attach first,
then map the problem state area.
Remove calls to cxl_assign_psn_space during init. The function is
already called on the attach paths.

Co-authored-by: Christophe Lombard 
Signed-off-by: Frederic Barrat 
Signed-off-by: Christophe Lombard 
Reviewed-by: Manoj Kumar 
Acked-by: Ian Munsie 
Signed-off-by: Michael Ellerman

cxl: Fix DSI misses when the context owning task exits

2016-01-05T05:28:25+00:00

Presently when a user-space process issues CXL_IOCTL_START_WORK ioctl we
store the pid of the current task_struct and use it to get pointer to
the mm_struct of the process, while processing page or segment faults
from the capi card. However this causes issues when the thread that had
originally issued the start-work ioctl exits in which case the stored
pid is no more valid and the cxl driver is unable to handle faults as
the mm_struct corresponding to process is no more accessible.

This patch fixes this issue by using the mm_struct of the next alive
task in the thread group. This is done by iterating over all the tasks
in the thread group starting from thread group leader and calling
get_task_mm on each one of them. When a valid mm_struct is obtained the
pid of the associated task is stored in the context replacing the
exiting one for handling future faults.

The patch introduces a new function named get_mem_context that checks if
the current task pointed to by ctx->pid is dead? If yes it performs the
steps described above. Also a new variable cxl_context.glpid is
introduced which stores the pid of the thread group leader associated
with the context owning task.

Reported-by: Matthew R. Ochs 
Reported-by: Frank Haverkamp 
Suggested-by: Ian Munsie 
Signed-off-by: Vaibhav Jain 
Acked-by: Ian Munsie 
Reviewed-by: Frederic Barrat 
Reviewed-by: Matthew R. Ochs 
Signed-off-by: Michael Ellerman

cxl: Fix possible idr warning when contexts are released

2015-11-24T03:21:27+00:00

An idr warning is reported when a context is release after the capi card
is unbound from the cxl driver via sysfs. Below are the steps to
reproduce:

1. Create multiple afu contexts in an user-space application using libcxl.
2. Unbind capi card from cxl using command of form
   echo  > /sys/bus/pci/drivers/cxl-pci/unbind
3. Exit/kill the application owning afu contexts.

After above steps a warning message is usually seen in the kernel logs
of the form "idr_remove called for id= which is not
allocated."

This is caused by the function cxl_release_afu which destroys the
contexts_idr table. So when a context is release no entry for context pe
is found in the contexts_idr table and idr code prints this warning.

This patch fixes this issue by increasing & decreasing the ref-count on
the afu device when a context is initialized or when its freed
respectively. This prevents the afu from being released until all the
afu contexts have been released. The patch introduces two new functions
namely cxl_afu_get/put that manage the ref-count on the afu device.

Also the patch removes code inside cxl_dev_context_init that increases ref
on the afu device as its guaranteed to be alive during this function.

Reported-by: Ian Munsie 
Signed-off-by: Vaibhav Jain 
Acked-by: Ian Munsie 
Signed-off-by: Michael Ellerman

cxl: fix leak of IRQ names in cxl_free_afu_irqs()

2015-10-01T01:49:32+00:00

cxl_free_afu_irqs() doesn't free IRQ names when it releases an AFU's IRQ
ranges. The userspace API equivalent in afu_release_irqs() calls
afu_irq_name_free() to release the IRQ names.

Call afu_irq_name_free() in cxl_free_afu_irqs() to release the IRQ names.
Make afu_irq_name_free() non-static to allow this.

Reported-by: Matthew R. Ochs 
Fixes: 6f7f0b3df6d4 ("cxl: Add AFU virtual PHB and kernel API")
Signed-off-by: Andrew Donnellan 
Signed-off-by: Ian Munsie 
Reviewed-by: Matthew R. Ochs 
Signed-off-by: Michael Ellerman

cxl: Fix force unmapping mmaps of contexts allocated through the kernel api

2015-08-30T08:47:26+00:00

The cxl user api uses the address_space associated with the file when we
need to force unmap all cxl mmap regions (e.g. on eeh, driver detach,
etc). Currently, contexts allocated through the kernel api do not do
this and instead skip the mmap invalidation, potentially allowing them
to poke at the hardware after such an event, which may cause all sorts
of trouble.

This patch allocates an address_space for cxl contexts allocated through
the kernel api so that the same invalidate path will for these contexts
as well. We don't use the anonymous inode's address_space, as doing so
could invalidate any mmaps of completely unrelated drivers using
anonymous file descriptors.

This patch also introduces a kernelapi flag, so we know when freeing the
context if the address_space was allocated by us and needs to be freed.

Signed-off-by: Ian Munsie 
Signed-off-by: Michael Ellerman

cxl: Fix + cleanup error paths in cxl_dev_context_init

2015-08-30T08:47:26+00:00

If the cxl_context_alloc() call fails, we return immediately without
releasing the reference on the AFU device, allowing it to leak.

This patch switches to using goto style error handling so that the
device is released in common code for both error paths, and will also
simplify things if we add additional initialisation in this function in
the future.

Signed-off-by: Ian Munsie 
Signed-off-by: Michael Ellerman