kernel-open/nvidia-uvm/uvm_va_space.h

/*******************************************************************************
    Copyright (c) 2015-2023 NVIDIA Corporation

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#ifndef __UVM_VA_SPACE_H__
#define __UVM_VA_SPACE_H__

#include "uvm_processors.h"
#include "uvm_global.h"
#include "uvm_gpu.h"
#include "uvm_range_tree.h"
#include "uvm_range_group.h"
#include "uvm_forward_decl.h"
#include "uvm_mmu.h"
#include "uvm_linux.h"
#include "uvm_common.h"
#include "nv-kref.h"
#include "nv-linux.h"
#include "uvm_perf_events.h"
#include "uvm_perf_module.h"
#include "uvm_va_block_types.h"
#include "uvm_va_block.h"
#include "uvm_hmm.h"
#include "uvm_test_ioctl.h"
#include "uvm_ats.h"
#include "uvm_va_space_mm.h"
#include "uvm_conf_computing.h"

// uvm_deferred_free_object provides a mechanism for building and later freeing
// a list of objects which are owned by a VA space, but can't be freed while the
// VA space lock is held.

typedef enum
{
    UVM_DEFERRED_FREE_OBJECT_TYPE_CHANNEL,
    UVM_DEFERRED_FREE_OBJECT_GPU_VA_SPACE,
    UVM_DEFERRED_FREE_OBJECT_TYPE_EXTERNAL_ALLOCATION,
    UVM_DEFERRED_FREE_OBJECT_TYPE_COUNT
} uvm_deferred_free_object_type_t;

typedef struct
{
    uvm_deferred_free_object_type_t type;
    struct list_head list_node;
} uvm_deferred_free_object_t;

static void uvm_deferred_free_object_add(struct list_head *list,
                                         uvm_deferred_free_object_t *object,
                                         uvm_deferred_free_object_type_t type)
{
    object->type = type;
    list_add_tail(&object->list_node, list);
}

// Walks the list of pending objects and frees each one as appropriate to its
// type.
//
// LOCKING: May take the GPU isr_lock and the RM locks.
void uvm_deferred_free_object_list(struct list_head *deferred_free_list);

typedef enum
{
    // The GPU VA space has been initialized but not yet inserted into the
    // parent VA space.
    UVM_GPU_VA_SPACE_STATE_INIT = 0,

    // The GPU VA space is active in the VA space.
    UVM_GPU_VA_SPACE_STATE_ACTIVE,

    // The GPU VA space is no longer active in the VA space. This state can be
    // observed when threads retain the gpu_va_space then drop the VA space
    // lock. After re-taking the VA space lock, the state must be inspected to
    // see if another thread unregistered the gpu_va_space in the meantime.
    UVM_GPU_VA_SPACE_STATE_DEAD,

    UVM_GPU_VA_SPACE_STATE_COUNT
} uvm_gpu_va_space_state_t;

struct uvm_gpu_va_space_struct
{
    // Parent pointers
    uvm_va_space_t *va_space;
    uvm_gpu_t *gpu;

    uvm_gpu_va_space_state_t state;

    // Handle to the duped GPU VA space
    // to be used for all further GPU VA space related UVM-RM interactions.
    uvmGpuAddressSpaceHandle duped_gpu_va_space;
    bool did_set_page_directory;

    uvm_page_tree_t page_tables;

    // List of all uvm_user_channel_t's under this GPU VA space
    struct list_head registered_channels;

    // List of all uvm_va_range_t's under this GPU VA space with type ==
    // UVM_VA_RANGE_TYPE_CHANNEL. Used at channel registration time to find
    // shareable VA ranges without having to iterate through all VA ranges in
    // the VA space.
    struct list_head channel_va_ranges;

    // Boolean which is 1 if no new channel registration is allowed. This is set
    // when all the channels under the GPU VA space have been stopped to prevent
    // new ones from entering after we drop the VA space lock. It is an atomic_t
    // because multiple threads may set it to 1 concurrently.
    atomic_t disallow_new_channels;

    // Node for the deferred free list where this GPU VA space is stored upon
    // being unregistered.
    uvm_deferred_free_object_t deferred_free;

    // Reference count for this gpu_va_space. This only protects the memory
    // object itself, for use in cases when the gpu_va_space needs to be
    // accessed across dropping and re-acquiring the VA space lock.
    nv_kref_t kref;

    // ATS specific state
    uvm_ats_gpu_va_space_t ats;
};

typedef struct
{
    int                  numa_node;

    uvm_processor_mask_t gpus;
} uvm_cpu_gpu_affinity_t;

struct uvm_va_space_struct
{
    // Mask of gpus registered with the va space
    uvm_processor_mask_t registered_gpus;

    // Array of pointers to the uvm_gpu_t objects that correspond to the
    // uvm_processor_id_t index.
    //
    // With SMC, GPUs can be partitioned so the number of uvm_gpu_t objects can
    // be larger than UVM_ID_MAX_GPUS. However, each VA space can only
    // subscribe to a single partition per GPU, so it is fine to have a regular
    // processor mask.
    uvm_gpu_t *registered_gpus_table[UVM_ID_MAX_GPUS];

    // Mask of processors registered with the va space that support replayable
    // faults.
    uvm_processor_mask_t faultable_processors;

    // Mask of processors registered with the va space that don't support
    // faulting.
    uvm_processor_mask_t non_faultable_processors;

    // This is a count of non fault capable processors with a GPU VA space
    // registered.
    NvU32 num_non_faultable_gpu_va_spaces;

    // Semaphore protecting the state of the va space
    uvm_rw_semaphore_t lock;

    // Lock taken prior to taking the VA space lock in write mode, or prior to
    // taking the VA space lock in read mode on a path which will call in RM.
    // See UVM_LOCK_ORDER_VA_SPACE_SERIALIZE_WRITERS in uvm_lock.h.
    uvm_mutex_t serialize_writers_lock;

    // Lock taken to serialize down_reads on the VA space lock with up_writes in
    // other threads. See
    // UVM_LOCK_ORDER_VA_SPACE_READ_ACQUIRE_WRITE_RELEASE_LOCK in uvm_lock.h.
    uvm_mutex_t read_acquire_write_release_lock;

    // Tree of uvm_va_range_t's
    uvm_range_tree_t va_range_tree;

    // Kernel mapping structure passed to unmap_mapping range to unmap CPU PTEs
    // in this process.
    struct address_space *mapping;

    // Storage in g_uvm_global.va_spaces.list
    struct list_head list_node;

    // Monotonically increasing counter for range groups IDs
    atomic64_t range_group_id_counter;

    // Range groups
    struct radix_tree_root range_groups;
    uvm_range_tree_t range_group_ranges;

    // Peer to peer table
    // A bitmask of peer to peer pairs enabled in this va_space
    // indexed by a peer_table_index returned by uvm_gpu_peer_table_index().
    DECLARE_BITMAP(enabled_peers, UVM_MAX_UNIQUE_GPU_PAIRS);

    // Temporary copy of the above state used to avoid allocation during VA
    // space destroy.
    DECLARE_BITMAP(enabled_peers_teardown, UVM_MAX_UNIQUE_GPU_PAIRS);

    // Interpreting these processor masks:
    //      uvm_processor_mask_test(foo[A], B)
    // ...should be read as "test if A foo B." For example:
    //      uvm_processor_mask_test(accessible_from[B], A)
    // means "test if B is accessible_from A."

    // Pre-computed masks that contain, for each processor, a mask of processors
    // which that processor can directly access. In other words, this will test
    // whether A has direct access to B:
    //      uvm_processor_mask_test(can_access[A], B)
    uvm_processor_mask_t can_access[UVM_ID_MAX_PROCESSORS];

    // Pre-computed masks that contain, for each processor memory, a mask with
    // the processors that have direct access enabled to its memory. This is the
    // opposite direction as can_access. In other words, this will test whether
    // A has direct access to B:
    //      uvm_processor_mask_test(accessible_from[B], A)
    uvm_processor_mask_t accessible_from[UVM_ID_MAX_PROCESSORS];

    // Pre-computed masks that contain, for each processor memory, a mask with
    // the processors that can directly copy to and from its memory. This is
    // almost the same as accessible_from masks, but also requires peer identity
    // mappings to be supported for peer access.
    uvm_processor_mask_t can_copy_from[UVM_ID_MAX_PROCESSORS];

    // Pre-computed masks that contain, for each processor, a mask of processors
    // to which that processor has NVLINK access. In other words, this will test
    // whether A has NVLINK access to B:
    //      uvm_processor_mask_test(has_nvlink[A], B)
    // This is a subset of can_access.
    uvm_processor_mask_t has_nvlink[UVM_ID_MAX_PROCESSORS];

    // Pre-computed masks that contain, for each processor memory, a mask with
    // the processors that have direct access to its memory and native support
    // for atomics in HW. This is a subset of accessible_from.
    uvm_processor_mask_t has_native_atomics[UVM_ID_MAX_PROCESSORS];

    // Pre-computed masks that contain, for each processor memory, a mask with
    // the processors that are indirect peers. Indirect peers can access each
    // other's memory like regular peers, but with additional latency and/or bw
    // penalty.
    uvm_processor_mask_t indirect_peers[UVM_ID_MAX_PROCESSORS];

    // Mask of gpu_va_spaces registered with the va space
    // indexed by gpu->id
    uvm_processor_mask_t registered_gpu_va_spaces;

    // Mask of GPUs which have temporarily dropped the VA space lock mid-
    // unregister. Used to make other paths return an error rather than
    // corrupting state.
    uvm_processor_mask_t gpu_unregister_in_progress;

    // Mask of processors that are participating in system-wide atomics
    uvm_processor_mask_t system_wide_atomics_enabled_processors;

    // Mask of physical GPUs where access counters are enabled on this VA space
    uvm_parent_processor_mask_t access_counters_enabled_processors;

    // Array with information regarding CPU/GPU NUMA affinity. There is one
    // entry per CPU NUMA node. Entries in the array are populated sequentially
    // as new CPU NUMA nodes are discovered on GPU registration. Each entry
    // contains a CPU NUMA node id, and a mask with the GPUs attached to it.
    // Since each GPU can only be attached to one CPU node id, the array can
    // contain information for up to UVM_ID_MAX_GPUS nodes. The information is
    // stored in the VA space to avoid taking the global lock.
    uvm_cpu_gpu_affinity_t gpu_cpu_numa_affinity[UVM_ID_MAX_GPUS];

    // Unregistering a GPU may trigger memory eviction from the GPU to the CPU.
    // This must happen without allocation, thus, a buffer is preallocated
    // at GPU register and freed at GPU unregister.
    uvm_conf_computing_dma_buffer_t *gpu_unregister_dma_buffer[UVM_ID_MAX_GPUS];

    // Array of GPU VA spaces
    uvm_gpu_va_space_t *gpu_va_spaces[UVM_ID_MAX_GPUS];

    // Tracking of GPU VA spaces which have dropped the VA space lock and are
    // pending destruction. uvm_va_space_mm_shutdown has to wait for those
    // destroy operations to be completely done.
    struct
    {
        atomic_t num_pending;
        wait_queue_head_t wait_queue;
    } gpu_va_space_deferred_free;

    // Per-va_space event notification information for performance heuristics
    uvm_perf_va_space_events_t perf_events;

    uvm_perf_module_data_desc_t perf_modules_data[UVM_PERF_MODULE_TYPE_COUNT];

    // Array of modules that are loaded in the va_space, indexed by module type
    uvm_perf_module_t *perf_modules[UVM_PERF_MODULE_TYPE_COUNT];

    // Lists of counters listening for events on this VA space
    // Protected by lock
    struct
    {
        bool enabled;

        uvm_rw_semaphore_t lock;

        // Lists of counters listening for events on this VA space
        struct list_head counters[UVM_TOTAL_COUNTERS];
        struct list_head queues_v1[UvmEventNumTypesAll];
        struct list_head queues_v2[UvmEventNumTypesAll];

        // Node for this va_space in global subscribers list
        struct list_head node;
    } tools;

    // Boolean which is 1 if all user channels have been already stopped. This
    // is an atomic_t because multiple threads may call
    // uvm_va_space_stop_all_user_channels concurrently.
    atomic_t user_channels_stopped;

    // Prevent future registrations of any kind (GPU, GPU VA space, channel).
    // This is used when the associated va_space_mm is torn down, which has to
    // prevent any new work from being started in this VA space.
    bool disallow_new_registers;

    bool user_channel_stops_are_immediate;

    // Block context used for GPU unmap operations so that allocation is not
    // required on the teardown path. This can only be used while the VA space
    // lock is held in write mode. Access using uvm_va_space_block_context().
    uvm_va_block_context_t *va_block_context;

    NvU64 initialization_flags;

    // The mm currently associated with this VA space, if any.
    uvm_va_space_mm_t va_space_mm;

    union
    {
        uvm_ats_va_space_t ats;

        // HMM information about this VA space.
        uvm_hmm_va_space_t hmm;
    };

    struct
    {
        bool  page_prefetch_enabled;
        bool  skip_migrate_vma;

        atomic_t migrate_vma_allocation_fail_nth;

        atomic_t va_block_allocation_fail_nth;

        uvm_thread_context_wrapper_t *dummy_thread_context_wrappers;
        size_t num_dummy_thread_context_wrappers;

        atomic64_t destroy_gpu_va_space_delay_us;

        atomic64_t split_invalidate_delay_us;

        bool force_cpu_to_cpu_copy_with_ce;

        bool allow_allocation_from_movable;
    } test;

    // Queue item for deferred f_ops->release() handling
    nv_kthread_q_item_t deferred_release_q_item;
};

static uvm_gpu_t *uvm_va_space_get_gpu(uvm_va_space_t *va_space, uvm_gpu_id_t gpu_id)
{
    uvm_gpu_t *gpu;

    UVM_ASSERT(uvm_processor_mask_test(&va_space->registered_gpus, gpu_id));

    gpu = va_space->registered_gpus_table[uvm_id_gpu_index(gpu_id)];

    UVM_ASSERT(gpu);
    UVM_ASSERT(uvm_gpu_get(gpu->id) == gpu);

    return gpu;
}

static const char *uvm_va_space_processor_name(uvm_va_space_t *va_space, uvm_processor_id_t id)
{
    if (UVM_ID_IS_CPU(id))
        return "0: CPU";
    else
        return uvm_gpu_name(uvm_va_space_get_gpu(va_space, id));
}

static void uvm_va_space_processor_uuid(uvm_va_space_t *va_space, NvProcessorUuid *uuid, uvm_processor_id_t id)
{
    if (UVM_ID_IS_CPU(id)) {
        memcpy(uuid, &NV_PROCESSOR_UUID_CPU_DEFAULT, sizeof(*uuid));
    }
    else {
        uvm_gpu_t *gpu = uvm_va_space_get_gpu(va_space, id);
        UVM_ASSERT(gpu);
        memcpy(uuid, &gpu->uuid, sizeof(*uuid));
    }
}

static bool uvm_va_space_processor_has_memory(uvm_va_space_t *va_space, uvm_processor_id_t id)
{
    if (UVM_ID_IS_CPU(id))
        return true;

    return uvm_va_space_get_gpu(va_space, id)->mem_info.size > 0;
}

NV_STATUS uvm_va_space_create(struct address_space *mapping, uvm_va_space_t **va_space_ptr, NvU64 flags);
void uvm_va_space_destroy(uvm_va_space_t *va_space);

// All VA space locking should be done with these wrappers. They're macros so
// lock assertions are attributed to line numbers correctly.

#define uvm_va_space_down_write(__va_space)                             \
    do {                                                                \
        uvm_mutex_lock(&(__va_space)->serialize_writers_lock);          \
        uvm_mutex_lock(&(__va_space)->read_acquire_write_release_lock); \
        uvm_down_write(&(__va_space)->lock);                            \
    } while (0)

#define uvm_va_space_up_write(__va_space)                                   \
    do {                                                                    \
        uvm_up_write(&(__va_space)->lock);                                  \
        uvm_mutex_unlock(&(__va_space)->read_acquire_write_release_lock);   \
        uvm_mutex_unlock(&(__va_space)->serialize_writers_lock);            \
    } while (0)

#define uvm_va_space_downgrade_write(__va_space)                                        \
    do {                                                                                \
        uvm_downgrade_write(&(__va_space)->lock);                                       \
        uvm_mutex_unlock_out_of_order(&(__va_space)->read_acquire_write_release_lock);  \
        uvm_mutex_unlock_out_of_order(&(__va_space)->serialize_writers_lock);           \
    } while (0)

// Call this when holding the VA space lock for write in order to downgrade to
// read on a path which also needs to make RM calls.
#define uvm_va_space_downgrade_write_rm(__va_space)                                     \
    do {                                                                                \
        uvm_assert_mutex_locked(&(__va_space)->serialize_writers_lock);                 \
        uvm_downgrade_write(&(__va_space)->lock);                                       \
        uvm_mutex_unlock_out_of_order(&(__va_space)->read_acquire_write_release_lock);  \
    } while (0)

#define uvm_va_space_down_read(__va_space)                                              \
    do {                                                                                \
        uvm_mutex_lock(&(__va_space)->read_acquire_write_release_lock);                 \
        uvm_down_read(&(__va_space)->lock);                                             \
        uvm_mutex_unlock_out_of_order(&(__va_space)->read_acquire_write_release_lock);  \
    } while (0)

// Call this if RM calls need to be made while holding the VA space lock in read
// mode. Note that taking read_acquire_write_release_lock is unnecessary since
// the down_read is serialized with another thread's up_write by the
// serialize_writers_lock.
#define uvm_va_space_down_read_rm(__va_space)                           \
    do {                                                                \
        uvm_mutex_lock(&(__va_space)->serialize_writers_lock);          \
        uvm_down_read(&(__va_space)->lock);                             \
    } while (0)

#define uvm_va_space_up_read(__va_space) uvm_up_read(&(__va_space)->lock)

#define uvm_va_space_up_read_rm(__va_space)                             \
    do {                                                                \
        uvm_up_read(&(__va_space)->lock);                               \
        uvm_mutex_unlock(&(__va_space)->serialize_writers_lock);        \
    } while (0)

// Get a registered gpu by uuid. This restricts the search for GPUs, to those
// that have been registered with a va_space. This returns NULL if the GPU is
// not present, or not registered with the va_space.
//
// LOCKING: The VA space lock must be held.
uvm_gpu_t *uvm_va_space_get_gpu_by_uuid(uvm_va_space_t *va_space, const NvProcessorUuid *gpu_uuid);

// Like uvm_va_space_get_gpu_by_uuid, but also returns NULL if the GPU does
// not have a GPU VA space registered in the UVM va_space.
//
// LOCKING: The VA space lock must be held.
uvm_gpu_t *uvm_va_space_get_gpu_by_uuid_with_gpu_va_space(uvm_va_space_t *va_space, const NvProcessorUuid *gpu_uuid);

// Same as uvm_va_space_get_gpu_by_uuid but it also retains the GPU. The caller
// cannot assume that the GPU is still registered in the VA space after the
// function returns.
//
// LOCKING: The function takes and releases the VA space lock in read mode.
uvm_gpu_t *uvm_va_space_retain_gpu_by_uuid(uvm_va_space_t *va_space, const NvProcessorUuid *gpu_uuid);

// Returns whether read-duplication is supported.
// If gpu is NULL, returns the current state.
// otherwise, it returns what the result would be once the gpu's va space is
// added or removed (by inverting the gpu's current state).
bool uvm_va_space_can_read_duplicate(uvm_va_space_t *va_space, uvm_gpu_t *changing_gpu);

// Register a gpu in the va space
// Note that each gpu can be only registered once in a va space
//
// The input gpu_uuid is for the phyisical GPU. The user_rm_va_space argument
// identifies the SMC partition if provided and SMC is enabled.
//
// This call returns whether the GPU memory is a NUMA node in the kernel and the
// corresponding node id.
// It also returns the GI UUID (if gpu_uuid is a SMC partition) or a copy of
// gpu_uuid if the GPU is not SMC capable or SMC is not enabled.
NV_STATUS uvm_va_space_register_gpu(uvm_va_space_t *va_space,
                                    const NvProcessorUuid *gpu_uuid,
                                    const uvm_rm_user_object_t *user_rm_va_space,
                                    NvBool *numa_enabled,
                                    NvS32 *numa_node_id,
                                    NvProcessorUuid *uuid_out);

// Unregister a gpu from the va space
NV_STATUS uvm_va_space_unregister_gpu(uvm_va_space_t *va_space, const NvProcessorUuid *gpu_uuid);

// Registers a GPU VA space with the UVM VA space.
NV_STATUS uvm_va_space_register_gpu_va_space(uvm_va_space_t *va_space,
                                             uvm_rm_user_object_t *user_rm_va_space,
                                             const NvProcessorUuid *gpu_uuid);

// Unregisters a GPU VA space from the UVM VA space.
NV_STATUS uvm_va_space_unregister_gpu_va_space(uvm_va_space_t *va_space, const NvProcessorUuid *gpu_uuid);

// Stop all user channels
//
// This function sets a flag in the VA space indicating that all the channels
// have been already stopped and should only be used when no new user channels
// can be registered.
//
// LOCKING: The VA space lock must be held in read mode, not write.
void uvm_va_space_stop_all_user_channels(uvm_va_space_t *va_space);

// Calls uvm_user_channel_detach on all user channels in a VA space.
//
// The detached channels are added to the input list. The caller is expected to
// drop the VA space lock and call uvm_deferred_free_object_list to complete the
// destroy operation.
//
// LOCKING: The owning VA space must be locked in write mode.
void uvm_va_space_detach_all_user_channels(uvm_va_space_t *va_space, struct list_head *deferred_free_list);

// Returns whether peer access between these two GPUs has been enabled in this
// VA space. Both GPUs must be registered in the VA space.
bool uvm_va_space_peer_enabled(uvm_va_space_t *va_space, const uvm_gpu_t *gpu0, const uvm_gpu_t *gpu1);

// Returns the va_space this file points to. Returns NULL if this file
// does not point to a va_space.
static uvm_va_space_t *uvm_fd_va_space(struct file *filp)
{
    uvm_va_space_t *va_space;
    uvm_fd_type_t type;

    type = uvm_fd_type(filp, (void **) &va_space);
    if (type != UVM_FD_VA_SPACE)
        return NULL;

    return va_space;
}

static uvm_va_space_t *uvm_va_space_get(struct file *filp)
{
    uvm_fd_type_t fd_type;
    uvm_va_space_t *va_space;

    fd_type = uvm_fd_type(filp, (void **)&va_space);
    UVM_ASSERT(uvm_file_is_nvidia_uvm(filp));
    UVM_ASSERT_MSG(fd_type == UVM_FD_VA_SPACE, "filp: 0x%llx", (NvU64)filp);

    return va_space;
}

static uvm_va_block_context_t *uvm_va_space_block_context(uvm_va_space_t *va_space, struct mm_struct *mm)
{
    uvm_assert_rwsem_locked_write(&va_space->lock);
    if (mm)
        uvm_assert_mmap_lock_locked(mm);

    uvm_va_block_context_init(va_space->va_block_context, mm);
    return va_space->va_block_context;
}

// Retains the GPU VA space memory object. destroy_gpu_va_space and
// uvm_gpu_va_space_release drop the count. This is used to keep the GPU VA
// space object allocated when dropping and re-taking the VA space lock. If
// another thread called remove_gpu_va_space in the meantime,
// gpu_va_space->state will be UVM_GPU_VA_SPACE_STATE_DEAD.
static inline void uvm_gpu_va_space_retain(uvm_gpu_va_space_t *gpu_va_space)
{
    nv_kref_get(&gpu_va_space->kref);
}

// This only frees the GPU VA space object itself, so it must have been removed
// from its VA space and destroyed prior to the final release.
void uvm_gpu_va_space_release(uvm_gpu_va_space_t *gpu_va_space);

// Wrapper for nvUvmInterfaceUnsetPageDirectory
void uvm_gpu_va_space_unset_page_dir(uvm_gpu_va_space_t *gpu_va_space);

static uvm_gpu_va_space_state_t uvm_gpu_va_space_state(uvm_gpu_va_space_t *gpu_va_space)
{
    UVM_ASSERT(gpu_va_space->gpu);
    UVM_ASSERT(gpu_va_space->va_space);

    return gpu_va_space->state;
}

// Return the GPU VA space for the given physical GPU.
// Locking: the va_space lock must be held.
uvm_gpu_va_space_t *uvm_gpu_va_space_get_by_parent_gpu(uvm_va_space_t *va_space,
                                                       uvm_parent_gpu_t *parent_gpu);

static uvm_gpu_va_space_t *uvm_gpu_va_space_get(uvm_va_space_t *va_space, uvm_gpu_t *gpu)
{
    uvm_gpu_va_space_t *gpu_va_space;

    if (!gpu)
        return NULL;

    gpu_va_space = uvm_gpu_va_space_get_by_parent_gpu(va_space, gpu->parent);
    if (gpu_va_space)
        UVM_ASSERT(gpu_va_space->gpu == gpu);

    return gpu_va_space;
}

#define for_each_gpu_va_space(__gpu_va_space, __va_space)                                                   \
    for (__gpu_va_space =                                                                                   \
            uvm_gpu_va_space_get(                                                                           \
                __va_space,                                                                                 \
                uvm_processor_mask_find_first_va_space_gpu(&__va_space->registered_gpu_va_spaces, va_space) \
            );                                                                                              \
         __gpu_va_space;                                                                                    \
         __gpu_va_space =                                                                                   \
            uvm_gpu_va_space_get(                                                                           \
                __va_space,                                                                                 \
                __uvm_processor_mask_find_next_va_space_gpu(&__va_space->registered_gpu_va_spaces,          \
                                                            va_space,                                       \
                                                            __gpu_va_space->gpu)                            \
            )                                                                                               \
        )

// Return the first GPU set in the given mask or NULL. The caller must ensure
// that the GPUs set in the mask are registered in the VA space and cannot be
// unregistered during this call.
static uvm_gpu_t *uvm_processor_mask_find_first_va_space_gpu(const uvm_processor_mask_t *mask, uvm_va_space_t *va_space)
{
    uvm_gpu_t *gpu;
    uvm_gpu_id_t gpu_id;

    UVM_ASSERT(uvm_processor_mask_gpu_subset(mask, &va_space->registered_gpus));

    gpu_id = uvm_processor_mask_find_first_gpu_id(mask);
    if (UVM_ID_IS_INVALID(gpu_id))
        return NULL;

    gpu = uvm_va_space_get_gpu(va_space, gpu_id);
    UVM_ASSERT_MSG(gpu, "gpu_id %u\n", uvm_id_value(gpu_id));

    return gpu;
}

static uvm_gpu_t *uvm_va_space_find_first_gpu(uvm_va_space_t *va_space)
{
    uvm_assert_rwsem_locked(&va_space->lock);

    return uvm_processor_mask_find_first_va_space_gpu(&va_space->registered_gpus, va_space);
}

// Same as uvm_processor_mask_find_next_va_space_gpu below, but gpu cannot be
// NULL
static uvm_gpu_t *__uvm_processor_mask_find_next_va_space_gpu(const uvm_processor_mask_t *mask,
                                                              uvm_va_space_t *va_space,
                                                              uvm_gpu_t *gpu)
{
    uvm_gpu_id_t gpu_id;

    UVM_ASSERT(gpu != NULL);
    UVM_ASSERT(uvm_processor_mask_gpu_subset(mask, &va_space->registered_gpus));

    gpu_id = uvm_processor_mask_find_next_id(mask, uvm_gpu_id_next(gpu->id));
    if (UVM_ID_IS_INVALID(gpu_id))
        return NULL;

    gpu = uvm_va_space_get_gpu(va_space, gpu_id);
    UVM_ASSERT_MSG(gpu, "gpu_id %u\n", uvm_id_value(gpu_id));

    return gpu;
}

// Return the next GPU with an id larger than gpu->id set in the given mask.
// The function returns NULL if gpu is NULL. The caller must ensure that the
// GPUs set in the mask are registered in the VA space and cannot be
// unregistered during this call.
static uvm_gpu_t *uvm_processor_mask_find_next_va_space_gpu(const uvm_processor_mask_t *mask,
                                                            uvm_va_space_t *va_space,
                                                            uvm_gpu_t *gpu)
{
    if (gpu == NULL)
        return NULL;

    return __uvm_processor_mask_find_next_va_space_gpu(mask, va_space, gpu);
}

#define for_each_va_space_gpu_in_mask(gpu, va_space, mask)                                       \
    for (({uvm_assert_rwsem_locked(&(va_space)->lock);                                           \
           gpu = uvm_processor_mask_find_first_va_space_gpu(mask, va_space);});                  \
           gpu != NULL;                                                                          \
           gpu = __uvm_processor_mask_find_next_va_space_gpu(mask, va_space, gpu))

// Helper to iterate over all GPUs registered in a UVM VA space
#define for_each_va_space_gpu(gpu, va_space) \
    for_each_va_space_gpu_in_mask(gpu, va_space, &(va_space)->registered_gpus)

// Return the processor in the candidates mask that is "closest" to src, or
// UVM_ID_MAX_PROCESSORS if candidates is empty. The order is:
// - src itself
// - Direct NVLINK GPU peers if src is CPU or GPU (1)
// - NVLINK CPU if src is GPU
// - Indirect NVLINK GPU peers if src is GPU
// - PCIe peers if src is GPU (2)
// - CPU if src is GPU
// - Deterministic selection from the pool of candidates
//
// (1) When src is a GPU, NVLINK GPU peers are preferred over the CPU because in
//     NUMA systems the CPU processor may refer to multiple CPU NUMA nodes, and
//     the bandwidth between src and the farthest CPU node can be substantially
//     lower than the bandwidth src and its peer GPUs.
// (2) TODO: Bug 1764943: Is copying from a PCI peer always better than copying
//     from CPU?
uvm_processor_id_t uvm_processor_mask_find_closest_id(uvm_va_space_t *va_space,
                                                      const uvm_processor_mask_t *candidates,
                                                      uvm_processor_id_t src);

// Iterate over each ID in mask in order of proximity to src. This is
// destructive to mask.
#define for_each_closest_id(id, mask, src, va_space)                    \
    for (id = uvm_processor_mask_find_closest_id(va_space, mask, src);  \
         UVM_ID_IS_VALID(id);                                           \
         uvm_processor_mask_clear(mask, id), id = uvm_processor_mask_find_closest_id(va_space, mask, src))

// Return the GPU whose memory corresponds to the given node_id
static uvm_gpu_t *uvm_va_space_find_gpu_with_memory_node_id(uvm_va_space_t *va_space, int node_id)
{
    uvm_gpu_t *gpu;

    UVM_ASSERT(nv_numa_node_has_memory(node_id));

    if (!g_uvm_global.ats.supported)
        return NULL;

    for_each_va_space_gpu(gpu, va_space) {
        if (uvm_gpu_numa_node(gpu) == node_id)
            return gpu;
    }

    return NULL;
}

static bool uvm_va_space_memory_node_is_gpu(uvm_va_space_t *va_space, int node_id)
{
    return uvm_va_space_find_gpu_with_memory_node_id(va_space, node_id) != NULL;
}

// Return a processor mask with the GPUs attached to the node_id CPU memory
// node
static void uvm_va_space_get_gpus_attached_to_cpu_node(uvm_va_space_t *va_space,
                                                       int node_id,
                                                       uvm_processor_mask_t *gpus)
{
    uvm_gpu_id_t gpu_id;

    UVM_ASSERT(!uvm_va_space_memory_node_is_gpu(va_space, node_id));

    for_each_gpu_id(gpu_id) {
        const uvm_cpu_gpu_affinity_t *affinity = &va_space->gpu_cpu_numa_affinity[uvm_id_gpu_index(gpu_id)];
        if (affinity->numa_node == node_id) {
            uvm_processor_mask_copy(gpus, &affinity->gpus);
            return;
        }
    }

    uvm_processor_mask_zero(gpus);
}

// Helper that returns the first GPU in the mask returned by
// uvm_va_space_get_gpus_attached_to_cpu_node or NULL if empty
static uvm_gpu_t *uvm_va_space_find_first_gpu_attached_to_cpu_node(uvm_va_space_t *va_space, int node_id)
{
    uvm_processor_mask_t gpus;

    uvm_va_space_get_gpus_attached_to_cpu_node(va_space, node_id, &gpus);

    return uvm_processor_mask_find_first_va_space_gpu(&gpus, va_space);
}

// Obtain the user channel with the given instance_ptr. This is used during
// non-replayable fault service. This function needs to be called with the va
// space lock held in order to prevent channels from being removed.
uvm_user_channel_t *uvm_gpu_va_space_get_user_channel(uvm_gpu_va_space_t *gpu_va_space,
                                                      uvm_gpu_phys_address_t instance_ptr);

// Whether some form of pageable access (ATS, HMM) is supported by the system on
// this VA space. This does NOT check whether GPUs with pageable support are
// present, just whether system + VA space support exists.
bool uvm_va_space_pageable_mem_access_supported(uvm_va_space_t *va_space);

NV_STATUS uvm_test_get_pageable_mem_access_type(UVM_TEST_GET_PAGEABLE_MEM_ACCESS_TYPE_PARAMS *params,
                                                 struct file *filp);
NV_STATUS uvm_test_enable_nvlink_peer_access(UVM_TEST_ENABLE_NVLINK_PEER_ACCESS_PARAMS *params, struct file *filp);
NV_STATUS uvm_test_disable_nvlink_peer_access(UVM_TEST_DISABLE_NVLINK_PEER_ACCESS_PARAMS *params, struct file *filp);
NV_STATUS uvm_test_destroy_gpu_va_space_delay(UVM_TEST_DESTROY_GPU_VA_SPACE_DELAY_PARAMS *params, struct file *filp);
NV_STATUS uvm_test_force_cpu_to_cpu_copy_with_ce(UVM_TEST_FORCE_CPU_TO_CPU_COPY_WITH_CE_PARAMS *params,
                                                 struct file *filp);
NV_STATUS uvm_test_va_space_allow_movable_allocations(UVM_TEST_VA_SPACE_ALLOW_MOVABLE_ALLOCATIONS_PARAMS *params,
                                                      struct file *filp);

// Handle a CPU fault in the given VA space for a managed allocation,
// performing any operations necessary to establish a coherent CPU mapping
// (migrations, cache invalidates, etc.).
//
// Locking:
//  - vma->vm_mm->mmap_lock must be held in at least read mode. Note, that
//    might not be the same as current->mm->mmap_lock.
// Returns:
// VM_FAULT_NOPAGE: if page was faulted in OK
//     (possibly or'ed with VM_FAULT_MAJOR if a migration was needed).
// VM_FAULT_OOM: if system memory wasn't available.
// VM_FAULT_SIGBUS: if a CPU mapping to fault_addr cannot be accessed,
//     for example because it's within a range group which is non-migratable.
vm_fault_t uvm_va_space_cpu_fault_managed(uvm_va_space_t *va_space,
                                          struct vm_area_struct *vma,
                                          struct vm_fault *vmf);

// Handle a CPU fault in the given VA space for a HMM allocation,
// performing any operations necessary to establish a coherent CPU mapping
// (migrations, cache invalidates, etc.).
//
// Locking:
//  - vma->vm_mm->mmap_lock must be held in at least read mode. Note, that
//    might not be the same as current->mm->mmap_lock.
// Returns:
// VM_FAULT_NOPAGE: if page was faulted in OK
//     (possibly or'ed with VM_FAULT_MAJOR if a migration was needed).
// VM_FAULT_OOM: if system memory wasn't available.
// VM_FAULT_SIGBUS: if a CPU mapping to fault_addr cannot be accessed.
vm_fault_t uvm_va_space_cpu_fault_hmm(uvm_va_space_t *va_space,
                                      struct vm_area_struct *vma,
                                      struct vm_fault *vmf);

#endif // __UVM_VA_SPACE_H__