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

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#ifndef __UVM_VA_POLICY_H__
#define __UVM_VA_POLICY_H__

#include "uvm_linux.h"
#include "uvm_forward_decl.h"
#include "uvm_processors.h"
#include "uvm_range_tree.h"
#include "uvm_va_block_types.h"

// This enum must be kept in sync with UVM_TEST_READ_DUPLICATION_POLICY in
// uvm_test_ioctl.h
typedef enum
{
    UVM_READ_DUPLICATION_UNSET = 0,
    UVM_READ_DUPLICATION_ENABLED,
    UVM_READ_DUPLICATION_DISABLED,
    UVM_READ_DUPLICATION_MAX
} uvm_read_duplication_policy_t;

typedef enum
{
    UVM_VA_POLICY_PREFERRED_LOCATION = 0,
    UVM_VA_POLICY_ACCESSED_BY,
    UVM_VA_POLICY_READ_DUPLICATION,
} uvm_va_policy_type_t;

//
// A policy covers one or more contiguous Linux VMAs or portion of a VMA and
// does not cover non-existant VMAs.
// The VA range is determined from either the uvm_va_range_t for managed
// allocations or the uvm_va_policy_node_t for HMM allocations.
//
struct uvm_va_policy_struct
{
    // Read duplication policy for this VA range (unset, enabled, or disabled).
    uvm_read_duplication_policy_t read_duplication;

    // Processor ID of the preferred location for this VA range.
    // This is set to UVM_ID_INVALID if no preferred location is set.
    uvm_processor_id_t preferred_location;

    // Mask of processors that are accessing this VA range and should have
    // their page tables updated to access the (possibly remote) pages.
    uvm_processor_mask_t accessed_by;

};

// Policy nodes are used for storing policies in HMM va_blocks.
// The va_block lock protects the tree so that invalidation callbacks can
// update the VA policy tree.
typedef struct uvm_va_policy_node_struct
{
    // Storage for the policy tree node. It also contains the range start and
    // end. Start and end + 1 have to be PAGE_SIZED aligned.
    uvm_range_tree_node_t node;

    uvm_va_policy_t policy;

} uvm_va_policy_node_t;

// Function pointer prototype for uvm_hmm_split_as_needed() callback.
typedef bool (*uvm_va_policy_is_split_needed_t)(const uvm_va_policy_t *policy, void *data);

// Default policy to save uvm_va_policy_node_t space in HMM va_blocks.
extern const uvm_va_policy_t uvm_va_policy_default;

// Return true if policy is the default policy.
static bool uvm_va_policy_is_default(const uvm_va_policy_t *policy)
{
    return policy == &uvm_va_policy_default;
}

bool uvm_va_policy_is_read_duplicate(const uvm_va_policy_t *policy, uvm_va_space_t *va_space);

// Returns the uvm_va_policy_t containing addr or default policy if not found.
// The va_block can be either a UVM or HMM va_block.
// Locking: The va_block lock must be held.
const uvm_va_policy_t *uvm_va_policy_get(uvm_va_block_t *va_block, NvU64 addr);

// Same as above but asserts the policy covers the whole region
const uvm_va_policy_t *uvm_va_policy_get_region(uvm_va_block_t *va_block, uvm_va_block_region_t region);

// Return a uvm_va_policy_node_t given a uvm_va_policy_t pointer.
static const uvm_va_policy_node_t *uvm_va_policy_node_from_policy(const uvm_va_policy_t *policy)
{
    return container_of(policy, uvm_va_policy_node_t, policy);
}

#if UVM_IS_CONFIG_HMM()

// Module load/exit
NV_STATUS uvm_va_policy_init(void);
void uvm_va_policy_exit(void);

// Returns the uvm_va_policy_node_t containing addr or NULL if not found.
// The va_block must be a HMM va_block.
// Locking: The va_block lock must be held.
uvm_va_policy_node_t *uvm_va_policy_node_find(uvm_va_block_t *va_block, NvU64 addr);

// Split the old node. The old node will end at 'new_end' and the new node will
// start at 'new_end' + 1 and end at old end.
// The va_block must be a HMM va_block.
// Locking: The va_block lock must be held.
NV_STATUS uvm_va_policy_node_split(uvm_va_block_t *va_block,
                                   uvm_va_policy_node_t *old,
                                   NvU64 new_end,
                                   uvm_va_policy_node_t **new_ptr);

// Move hints from 'old' to 'new' which must both be HMM va_blocks.
// The old va_block policies should have been pre-split and since we don't
// merge policy ranges, they should still be split after locking/unlocking
// 'old'. This should be called after splitting a block.
// TODO: Bug 1707562: Add support for merging policy ranges.
// Locking: The va_block lock must be held for both old and new.
void uvm_va_policy_node_split_move(uvm_va_block_t *old_va_block,
                                   uvm_va_block_t *new_va_block);

// Remove all policy in the given range start/end where 'end' is inclusive.
// This function may clear a range larger than start/end if clearing the range
// requires memory allocation and the memory allocation fails.
// The va_block must be a HMM va_block.
// Locking: The va_block lock must be held.
void uvm_va_policy_clear(uvm_va_block_t *va_block, NvU64 start, NvU64 end);

// Fill in any missing policy nodes for the given range and set the policy
// to the given value. The caller is expected to split any policy nodes
// before calling this function so the range being set does not.
// The va_block must be a HMM va_block.
// Note that start and end + 1 must be page aligned, 'end' is inclusive.
// TODO: Bug 1707562: Add support for merging policy ranges.
// Locking: The va_block lock must be held.
NV_STATUS uvm_va_policy_set_range(uvm_va_block_t *va_block,
                                  NvU64 start,
                                  NvU64 end,
                                  uvm_va_policy_type_t which,
                                  bool is_default,
                                  uvm_processor_id_t processor_id,
                                  uvm_read_duplication_policy_t new_policy);

// This is an optimized version of uvm_va_policy_set_range() where the caller
// guarantees that the the processor_id is not the same as the existing
// policy for the given region and that the region doesn't require splitting
// the existing policy node 'old_policy'.
// Returns the updated policy or NULL if memory could not be allocated.
// Locking: The va_block lock must be held.
const uvm_va_policy_t *uvm_va_policy_set_preferred_location(uvm_va_block_t *va_block,
                                                            uvm_va_block_region_t region,
                                                            uvm_processor_id_t processor_id,
                                                            const uvm_va_policy_t *old_policy);

// Iterators for specific VA policy ranges.

// Returns the first policy node in the range [start, end], if any.
// The va_block must be a HMM va_block.
// Locking: The va_block lock must be held.
uvm_va_policy_node_t *uvm_va_policy_node_iter_first(uvm_va_block_t *va_block, NvU64 start, NvU64 end);

// Returns the next VA policy following the provided policy in address order,
// if that policy's start <= the provided end.
// The va_block must be a HMM va_block.
// Locking: The va_block lock must be held.
uvm_va_policy_node_t *uvm_va_policy_node_iter_next(uvm_va_block_t *va_block, uvm_va_policy_node_t *node, NvU64 end);

#define uvm_for_each_va_policy_node_in(node, va_block, start, end)            \
    for ((node) = uvm_va_policy_node_iter_first((va_block), (start), (end));  \
         (node);                                                              \
         (node) = uvm_va_policy_node_iter_next((va_block), (node), (end)))

#define uvm_for_each_va_policy_node_in_safe(node, next, va_block, start, end) \
    for ((node) = uvm_va_policy_node_iter_first((va_block), (start), (end)),  \
         (next) = uvm_va_policy_node_iter_next((va_block), (node), (end));    \
         (node);                                                              \
         (node) = (next),                                                     \
         (next) = uvm_va_policy_node_iter_next((va_block), (node), (end)))

// Returns the first policy in the range [start, end], if any.
// Locking: The va_block lock must be held.
const uvm_va_policy_t *uvm_va_policy_iter_first(uvm_va_block_t *va_block,
                                                NvU64 start,
                                                NvU64 end,
                                                uvm_va_policy_node_t **out_node,
                                                uvm_va_block_region_t *out_region);

// Returns the next VA policy following the provided policy in address order,
// if that policy's start <= the provided end.
// Locking: The va_block lock must be held.
const uvm_va_policy_t *uvm_va_policy_iter_next(uvm_va_block_t *va_block,
                                               const uvm_va_policy_t *policy,
                                               NvU64 end,
                                               uvm_va_policy_node_t **inout_node,
                                               uvm_va_block_region_t *inout_region);

// Note that policy and region are set and usable in the loop body.
// The 'node' variable is used to retain loop state and 'policy' doesn't
// necessarily match &node->policy.
#define uvm_for_each_va_policy_in(policy, va_block, start, end, node, region) \
    for ((policy) = uvm_va_policy_iter_first((va_block), (start), (end), &(node), &(region)); \
         (policy);                                                              \
         (policy) = uvm_va_policy_iter_next((va_block), (policy), (end), &(node), &(region)))

#else // UVM_IS_CONFIG_HMM()

static NV_STATUS uvm_va_policy_init(void)
{
    return NV_OK;
}

static void uvm_va_policy_exit(void)
{
}

static uvm_va_policy_node_t *uvm_va_policy_node_find(uvm_va_block_t *va_block, NvU64 addr)
{
    UVM_ASSERT(0);
    return NULL;
}

static NV_STATUS uvm_va_policy_node_split(uvm_va_block_t *va_block,
                                          uvm_va_policy_node_t *old,
                                          NvU64 new_end,
                                          uvm_va_policy_node_t **new_ptr)
{
    return NV_OK;
}

static void uvm_va_policy_node_split_move(uvm_va_block_t *old_va_block,
                                          uvm_va_block_t *new_va_block)
{
}

static void uvm_va_policy_clear(uvm_va_block_t *va_block, NvU64 start, NvU64 end)
{
}

static NV_STATUS uvm_va_policy_set_range(uvm_va_block_t *va_block,
                                         NvU64 start,
                                         NvU64 end,
                                         uvm_va_policy_type_t which,
                                         bool is_default,
                                         uvm_processor_id_t processor_id,
                                         uvm_read_duplication_policy_t new_policy)
{
    return NV_OK;
}

static uvm_va_policy_node_t *uvm_va_policy_node_iter_first(uvm_va_block_t *va_block, NvU64 start, NvU64 end)
{
    return NULL;
}

#endif // UVM_IS_CONFIG_HMM()

#endif // __UVM_VA_POLICY_H__