open-gpu-kernel-modules/kernel-open/nvidia-uvm/uvm_perf_events.h

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#ifndef __UVM_PERF_EVENTS_H__
#define __UVM_PERF_EVENTS_H__

#include "uvm_linux.h"
#include "uvm_forward_decl.h"
#include "uvm_processors.h"
#include "uvm_hal_types.h"
#include "uvm_lock.h"
#include "uvm_va_block_types.h"

// uvm_perf_events is an event notification dispatcher that broadcasts events
// to clients. Clients register functions to be called under specific events.
// The callback lists are stored per va_space and, therefore, different
// callbacks can be registered per client. This will be useful to use
// different performance heuristic implementations depending on the GPU
// resources used by each process. For example, on a system with Pascal +
// Maxwell GPUs, VA spaces which have Maxwell GPU VA spaces will be restrited
// to the UVM-Lite feature set, while a VA space which only uses the Pascal
// GPU will not be downgraded. Registering/unregistering callbacks requires
// holding the VA space events lock in write mode. The exact locking
// guarantees under which callbacks are executed depend on the specific event,
// but the VA space events lock is held in read mode for all of them. The
// additional locking guarantees are defined in each event definition.

// Performance-related events that can be notified
typedef enum
{
    // Locking: uvm_va_space: at least in read mode, uvm_va_block: exclusive / nobody is referencing the block anymore
    UVM_PERF_EVENT_BLOCK_DESTROY = 0,

    // Locking: uvm_va_space: write
    UVM_PERF_EVENT_BLOCK_SHRINK,

    // Locking: uvm_va_space: write
    UVM_PERF_EVENT_RANGE_DESTROY,

    // Locking: uvm_va_space: write
    UVM_PERF_EVENT_RANGE_SHRINK,

    // Locking: uvm_va_space: write
    UVM_PERF_EVENT_MODULE_UNLOAD,

    // Locking: uvm_va_space: at least in read mode, uvm_va_block: exclusive (if uvm_va_block is not NULL)
    UVM_PERF_EVENT_FAULT,

    // Locking: uvm_va_block: exclusive. Notably the uvm_va_space lock may not be held on eviction.
    UVM_PERF_EVENT_MIGRATION,

    // Locking: uvm_va_space: at least in read mode, uvm_va_block: exclusive
    UVM_PERF_EVENT_REVOCATION,

    UVM_PERF_EVENT_COUNT,
} uvm_perf_event_t;

// Format of the data passed to callbacks. Scope must be filled with the appropriate values by the code which notifies
// the event
typedef union
{
    struct
    {
        uvm_va_block_t *block;
    } block_destroy;

    struct
    {
        uvm_va_block_t *block;
    } block_shrink;

    struct
    {
        uvm_va_range_t *range;
    } range_destroy;

    struct
    {
        uvm_va_range_t *range;
    } range_shrink;

    struct
    {
        uvm_perf_module_t *module;

        // Only one of these two can be set. The other one must be NULL
        uvm_va_block_t *block;
        uvm_va_range_t *range;
    } module_unload;

    struct
    {
        // This field contains the VA space where this fault was reported.
        // If block is not NULL, this field must match
        // uvm_va_block_get_va_space(block).
        uvm_va_space_t *space;

        // VA block for the page where the fault was triggered if it exists,
        // NULL otherwise (this can happen if the fault is fatal or the
        // VA block could not be created).
        uvm_va_block_t *block;

        // ID of the faulting processor
        uvm_processor_id_t proc_id;

        // ID of the preferred location processor
        uvm_processor_id_t preferred_location;

        // Fault descriptor
        union
        {
            struct
            {
                uvm_fault_buffer_entry_t *buffer_entry;

                NvU32 batch_id;

                bool is_duplicate;
            } gpu;

            struct
            {
                NvU64 fault_va;

                bool is_write;

                NvU64 pc;
            } cpu;
        };
    } fault;

    // This event is emitted during migration and the residency bits may be
    // stale. Do not rely on them in the callbacks.
    struct
    {
        uvm_push_t *push;
        uvm_va_block_t *block;

        // ID of the destination processor of the migration
        uvm_processor_id_t dst;

        // ID of the source processor of the migration
        uvm_processor_id_t src;

        // Start address of the memory range being migrated
        NvU64 address;

        // Number of bytes being migrated
        NvU64 bytes;

        // Whether the page has been copied or moved
        uvm_va_block_transfer_mode_t transfer_mode;

        // Event that performed the call to make_resident
        uvm_make_resident_cause_t cause;

        // Pointer to the make_resident context from the va_block_context
        // struct used by the operation that triggered the make_resident call.
        uvm_make_resident_context_t *make_resident_context;
    } migration;

    struct
    {
        uvm_va_block_t *block;

        // ID of the processor whose access permissions have been revoked
        uvm_processor_id_t proc_id;

        // Start address of the memory range being revoked
        NvU64 address;

        // Number of bytes of the memory range being revoked
        NvU64 bytes;

        // Old access permission
        uvm_prot_t old_prot;

        // New access permission
        uvm_prot_t new_prot;
    } revocation;
} uvm_perf_event_data_t;

// Type of the function that can be registered as a callback
//
// event_id: is the event being notified. Passing it to the callback enables using the same function to handle
//           different events.
// event_data: extra event data that is passed to the callback function. The format of data passed for each event type
//             is declared in the uvm_perf_event_data_t union
typedef void (*uvm_perf_event_callback_t)(uvm_perf_event_t event_id, uvm_perf_event_data_t *event_data);

typedef struct
{
    // Lock protecting the events
    //
    // Held for write during registration/unregistration of callbacks and for
    // read during notification of events.
    //
    // Also used by tools to protect their state and registration of perf event callbacks.
    uvm_rw_semaphore_t lock;

    // Array of callbacks for event notification
    struct list_head event_callbacks[UVM_PERF_EVENT_COUNT];

    uvm_va_space_t *va_space;
} uvm_perf_va_space_events_t;

// Initialize event notifiction for a va_space. This must be called from va_space construction. No locking required
NV_STATUS uvm_perf_init_va_space_events(uvm_va_space_t *va_space, uvm_perf_va_space_events_t *va_space_events);

// Finalize event notifiction for a va_space. Caller must hold va_space lock in write mode
void uvm_perf_destroy_va_space_events(uvm_perf_va_space_events_t *va_space_events);

// Register a callback to be executed under the given event. The given callback cannot have been already registered for
// the same event, although the same callback can be registered for different events.
NV_STATUS uvm_perf_register_event_callback(uvm_perf_va_space_events_t *va_space_events,
                                           uvm_perf_event_t event_id, uvm_perf_event_callback_t callback);

// Same as uvm_perf_register_event_callback(), but the caller must hold
// va_space_events lock in write mode.
NV_STATUS uvm_perf_register_event_callback_locked(uvm_perf_va_space_events_t *va_space_events,
                                                  uvm_perf_event_t event_id, uvm_perf_event_callback_t callback);

// Removes a callback for the given event. It's safe to call with a callback that hasn't been registered.
void uvm_perf_unregister_event_callback(uvm_perf_va_space_events_t *va_space_events, uvm_perf_event_t event_id,
                                        uvm_perf_event_callback_t callback);

// Same as uvm_perf_unregister_event_callback(), but the caller must hold
// va_space_events lock in write mode.
void uvm_perf_unregister_event_callback_locked(uvm_perf_va_space_events_t *va_space_events, uvm_perf_event_t event_id,
                                               uvm_perf_event_callback_t callback);

// Invoke the callbacks registered for the given event. Callbacks cannot fail.
// Acquires the va_space_events lock internally
void uvm_perf_event_notify(uvm_perf_va_space_events_t *va_space_events, uvm_perf_event_t event_id,
                           uvm_perf_event_data_t *event_data);

// Checks if the given callback is already registered for the event.
// va_space_events.lock must be held in either mode by the caller.
bool uvm_perf_is_event_callback_registered(uvm_perf_va_space_events_t *va_space_events,
                                           uvm_perf_event_t event_id,
                                           uvm_perf_event_callback_t callback);

// Initialization/cleanup functions
NV_STATUS uvm_perf_events_init(void);
void uvm_perf_events_exit(void);

// Helper to notify migration events
static inline void uvm_perf_event_notify_migration(uvm_perf_va_space_events_t *va_space_events,
                                                   uvm_push_t *push,
                                                   uvm_va_block_t *va_block,
                                                   uvm_processor_id_t dst,
                                                   uvm_processor_id_t src,
                                                   NvU64 address,
                                                   NvU64 bytes,
                                                   uvm_va_block_transfer_mode_t transfer_mode,
                                                   uvm_make_resident_cause_t cause,
                                                   uvm_make_resident_context_t *make_resident_context)
{
    uvm_perf_event_data_t event_data =
        {
            .migration =
                {
                    .push                  = push,
                    .block                 = va_block,
                    .dst                   = dst,
                    .src                   = src,
                    .address               = address,
                    .bytes                 = bytes,
                    .transfer_mode         = transfer_mode,
                    .cause                 = cause,
                    .make_resident_context = make_resident_context,
                }
        };

    uvm_perf_event_notify(va_space_events, UVM_PERF_EVENT_MIGRATION, &event_data);
}

// Helper to notify gpu fault events
static inline void uvm_perf_event_notify_gpu_fault(uvm_perf_va_space_events_t *va_space_events,
                                                   uvm_va_block_t *va_block,
                                                   uvm_gpu_id_t gpu_id,
                                                   uvm_processor_id_t preferred_location,
                                                   uvm_fault_buffer_entry_t *buffer_entry,
                                                   NvU32 batch_id,
                                                   bool is_duplicate)
{
    uvm_perf_event_data_t event_data =
        {
            .fault =
                {
                    .space            = va_space_events->va_space,
                    .block            = va_block,
                    .proc_id          = gpu_id,
                    .preferred_location = preferred_location,
                },
        };

    event_data.fault.gpu.buffer_entry = buffer_entry;
    event_data.fault.gpu.batch_id     = batch_id;
    event_data.fault.gpu.is_duplicate = is_duplicate;

    uvm_perf_event_notify(va_space_events, UVM_PERF_EVENT_FAULT, &event_data);
}

// Helper to notify cpu fault events
static inline void uvm_perf_event_notify_cpu_fault(uvm_perf_va_space_events_t *va_space_events,
                                                   uvm_va_block_t *va_block,
                                                   uvm_processor_id_t preferred_location,
                                                   NvU64 fault_va,
                                                   bool is_write,
                                                   NvU64 pc)
{
    uvm_perf_event_data_t event_data =
        {
            .fault =
                {
                    .space         = va_space_events->va_space,
                    .block         = va_block,
                    .proc_id       = UVM_ID_CPU,
                    .preferred_location = preferred_location,
                }
        };

     event_data.fault.cpu.fault_va = fault_va,
     event_data.fault.cpu.is_write = is_write,
     event_data.fault.cpu.pc       = pc,

    uvm_perf_event_notify(va_space_events, UVM_PERF_EVENT_FAULT, &event_data);
}

// Helper to notify permission revocation
static inline void uvm_perf_event_notify_revocation(uvm_perf_va_space_events_t *va_space_events,
                                                    uvm_va_block_t *va_block,
                                                    uvm_processor_id_t id,
                                                    NvU64 addr,
                                                    NvU64 bytes,
                                                    uvm_prot_t old_prot,
                                                    uvm_prot_t new_prot)
{
    uvm_perf_event_data_t event_data =
        {
            .revocation =
                {
                    .block = va_block,
                    .proc_id = id,
                    .address = addr,
                    .bytes   = bytes,
                    .old_prot = old_prot,
                    .new_prot = new_prot,
                }
        };

    uvm_perf_event_notify(va_space_events, UVM_PERF_EVENT_REVOCATION, &event_data);
}

#endif