BMC/Intel-BMC/linux.git/drivers/misc/cxl/api.c, branch dev-4.10

cxl: Fix coredump generation when cxl_get_fd() is used

2016-11-18T12:02:17+00:00

If a process dumps core while owning a cxl file descriptor obtained from an AFU driver (e.g. cxlflash) through the cxl_get_fd() API, the following error occurs: [ 868.027591] Unable to handle kernel paging request for data at address ... [ 868.027778] Faulting instruction address: 0xc00000000035edb0 cpu 0x8c: Vector: 300 (Data Access) at [c000003c688275e0] pc: c00000000035edb0: elf_core_dump+0xd60/0x1300 lr: c00000000035ed80: elf_core_dump+0xd30/0x1300 sp: c000003c68827860 msr: 9000000100009033 dar: c dsisr: 40000000 current = 0xc000003c68780000 paca = 0xc000000001b73200 softe: 0 irq_happened: 0x01 pid = 46725, comm = hxesurelock enter ? for help [c000003c68827a60] c00000000036948c do_coredump+0xcec/0x11e0 [c000003c68827c20] c0000000000ce9e0 get_signal+0x540/0x7b0 [c000003c68827d10] c000000000017354 do_signal+0x54/0x2b0 [c000003c68827e00] c00000000001777c do_notify_resume+0xbc/0xd0 [c000003c68827e30] c000000000009838 ret_from_except_lite+0x64/0x68 --- Exception: 300 (Data Access) at 00003fff98ad2918 The root cause is that the address_space structure for the file doesn't define a 'host' member. When cxl allocates a file descriptor, it's using the anonymous inode to back the file, but allocates a private address_space for each context. The private address_space allows to track memory allocation for each context. cxl doesn't define the 'host' member of the address space, i.e. the inode. We don't want to define it as the anonymous inode, since there's no longer a 1-to-1 relation between address_space and inode. To fix it, instead of using the anonymous inode, we introduce a simple pseudo filesystem so that cxl can allocate its own inodes. So we now have one inode for each file and address_space. The pseudo filesystem is only mounted on the first allocation of a file descriptor by cxl_get_fd(). Tested with cxlflash. Signed-off-by: Frederic Barrat Reviewed-by: Matthew R. Ochs Signed-off-by: Michael Ellerman

cxl: Fix error handling in _cxl_cx4_setup_msi_irqs()

2016-11-18T11:41:08+00:00

'cxl_dev_context_init()' returns an error pointer in case of error, not NULL. So test it with IS_ERR. Signed-off-by: Christophe JAILLET Reviewed-by: Andrew Donnellan Acked-by: Frederic Barrat Acked-by: Ian Munsie Signed-off-by: Michael Ellerman

cxl: Fix memory allocation failure test

2016-11-18T11:41:08+00:00

'cxl_context_alloc()' does not return an error pointer. It is just a shortcut for a call to 'kzalloc' with 'sizeof(struct cxl_context)' as the size parameter. So its return value should be compared with NULL. While fixing it, simplify a bit the code. Signed-off-by: Christophe JAILLET Reviewed-by: Andrew Donnellan Acked-by: Frederic Barrat Acked-by: Ian Munsie Signed-off-by: Michael Ellerman

cxl: Fix leaking pid refs in some error paths

2016-10-24T00:38:27+00:00

In some error paths in functions cxl_start_context and afu_ioctl_start_work pid references to the current & group-leader tasks can leak after they are taken. This patch fixes these error paths to release these pid references before exiting the error path. Fixes: 7b8ad495d592 ("cxl: Fix DSI misses when the context owning task exits") Cc: stable@vger.kernel.org # v4.5+ Reviewed-by: Andrew Donnellan Reported-by: Frederic Barrat Signed-off-by: Vaibhav Jain Acked-by: Frederic Barrat Signed-off-by: Michael Ellerman

cxl: Prevent adapter reset if an active context exists

2016-10-19T09:35:39+00:00

This patch prevents resetting the cxl adapter via sysfs in presence of one or more active cxl_context on it. This protects against an unrecoverable error caused by PSL owning a dirty cache line even after reset and host tries to touch the same cache line. In case a force reset of the card is required irrespective of any active contexts, the int value -1 can be stored in the 'reset' sysfs attribute of the card. The patch introduces a new atomic_t member named contexts_num inside struct cxl that holds the number of active context attached to the card , which is checked against '0' before proceeding with the reset. To prevent against a race condition where a context is activated just after reset check is performed, the contexts_num is atomically set to '-1' after reset-check to indicate that no more contexts can be activated on the card anymore. Before activating a context we atomically test if contexts_num is non-negative and if so, increment its value by one. In case the value of contexts_num is negative then it indicates that the card is about to be reset and context activation is error-ed out at that point. Fixes: 62fa19d4b4fd ("cxl: Add ability to reset the card") Cc: stable@vger.kernel.org # v4.0+ Acked-by: Frederic Barrat Reviewed-by: Andrew Donnellan Signed-off-by: Vaibhav Jain Signed-off-by: Michael Ellerman

cxl: Add support for interrupts on the Mellanox CX4

2016-07-14T10:27:08+00:00

The Mellanox CX4 in cxl mode uses a hybrid interrupt model, where interrupts are routed from the networking hardware to the XSL using the MSIX table, and from there will be transformed back into an MSIX interrupt using the cxl style interrupts (i.e. using IVTE entries and ranges to map a PE and AFU interrupt number to an MSIX address). We want to hide the implementation details of cxl interrupts as much as possible. To this end, we use a special version of the MSI setup & teardown routines in the PHB while in cxl mode to allocate the cxl interrupts and configure the IVTE entries in the process element. This function does not configure the MSIX table - the CX4 card uses a custom format in that table and it would not be appropriate to fill that out in generic code. The rest of the functionality is similar to the "Full MSI-X mode" described in the CAIA, and this could be easily extended to support other adapters that use that mode in the future. The interrupts will be associated with the default context. If the maximum number of interrupts per context has been limited (e.g. by the mlx5 driver), it will automatically allocate additional kernel contexts to associate extra interrupts as required. These contexts will be started using the same WED that was used to start the default context. Signed-off-by: Ian Munsie Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman

cxl: Add preliminary workaround for CX4 interrupt limitation

2016-07-14T10:27:02+00:00

The Mellanox CX4 has a hardware limitation where only 4 bits of the AFU interrupt number can be passed to the XSL when sending an interrupt, limiting it to only 15 interrupts per context (AFU interrupt number 0 is invalid). In order to overcome this, we will allocate additional contexts linked to the default context as extra address space for the extra interrupts - this will be implemented in the next patch. This patch adds the preliminary support to allow this, by way of adding a linked list in the context structure that we use to keep track of the contexts dedicated to interrupts, and an API to simultaneously iterate over the related context structures, AFU interrupt numbers and hardware interrupt numbers. The point of using a single API to iterate these is to hide some of the details of the iteration from external code, and to reduce the number of APIs that need to be exported via base.c to allow built in code to call. Signed-off-by: Ian Munsie Reviewed-by: Frederic Barrat Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman

cxl: Add kernel APIs to get & set the max irqs per context

2016-07-14T10:26:57+00:00

These APIs will be used by the Mellanox CX4 support. While they function standalone to configure existing behaviour, their primary purpose is to allow the Mellanox driver to inform the cxl driver of a hardware limitation, which will be used in a future patch. Signed-off-by: Ian Munsie Reviewed-by: Frederic Barrat Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman

cxl: Add support for using the kernel API with a real PHB

2016-07-14T10:26:56+00:00

This hooks up support for using the kernel API with a real PHB. After the AFU initialisation has completed it calls into the PHB code to pass it the AFU that will be used by other peer physical functions on the adapter. The cxl_pci_to_afu API is extended to work with peer PCI devices, retrieving the peer AFU from the PHB. This API may also now return an error if it is called on a PCI device that is not associated with either a cxl vPHB or a peer PCI device to an AFU, and this error is propagated down. Signed-off-by: Ian Munsie Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman

cxl: Add set and get private data to context struct

2016-06-28T08:35:08+00:00

This provides AFU drivers a means to associate private data with a cxl context. This is particularly intended for make the new callbacks for driver specific events easier for AFU drivers to use, as they can easily get back to any private data structures they may use. Signed-off-by: Michael Neuling Signed-off-by: Ian Munsie Signed-off-by: Philippe Bergheaud Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman