kernel/linux.git/drivers/misc/cxl/api.c, branch v4.7.4

cxl: Add kernel API to allow a context to operate with relocate disabled

2016-05-11T11:54:10+00:00

cxl devices typically access memory using an MMU in much the same way as the CPU, and each context includes a state register much like the MSR in the CPU. Like the CPU, the state register includes a bit to enable relocation, which we currently always enable. In some cases, it may be desirable to allow a device to access memory using real addresses instead of effective addresses, so this adds a new API, cxl_set_translation_mode, that can be used to disable relocation on a given kernel context. This can allow for the creation of a special privileged context that the device can use if it needs relocation disabled, and can use regular contexts at times when it needs relocation enabled. This interface is only available to users of the kernel API for obvious reasons, and will never be supported in a virtualised environment. This will be used by the upcoming cxl support in the mlx5 driver. Signed-off-by: Ian Munsie Signed-off-by: Michael Ellerman

cxl: Remove dead code

2016-04-11T01:23:39+00:00

Function cxl_get_phys_dev() was removed from the kernel API by a previous patch, but it's actually dead code. Remove it. Signed-off-by: Frederic Barrat Acked-by: Ian Munsie Reviewed-by: Andrew Donnellan Acked-by: Michael Neuling Signed-off-by: Michael Ellerman

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