xref: /open-nvidia-gpu/kernel-open/nvidia-uvm/uvm_pmm_sysmem.h (revision 4397463e)

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#ifndef __UVM_PMM_SYSMEM_H__
#define __UVM_PMM_SYSMEM_H__

#include "uvm_common.h"
#include "uvm_linux.h"
#include "uvm_forward_decl.h"
#include "uvm_lock.h"
#include "uvm_pmm_gpu.h"

// Module to handle per-GPU user mappings to sysmem physical memory. Notably,
// this implements a reverse map of the DMA address to {va_block, virt_addr}.
// This is required by the GPU access counters feature since they may provide a
// physical address in the notification packet (GPA notifications). We use the
// table to obtain the VAs of the memory regions being accessed remotely. The
// reverse map is implemented by a radix tree, which is indexed using the
// DMA address. For now, only PAGE_SIZE translations are supported (i.e. no
// big/huge pages).
//
// TODO: Bug 1995015: add support for physically-contiguous mappings.
struct uvm_pmm_sysmem_mappings_struct
{
    uvm_gpu_t                                      *gpu;

    struct radix_tree_root             reverse_map_tree;

    uvm_mutex_t                        reverse_map_lock;
};

// See comments in uvm_linux.h
#ifdef NV_RADIX_TREE_REPLACE_SLOT_PRESENT
#define uvm_pmm_sysmem_mappings_indirect_supported() true
#else
#define uvm_pmm_sysmem_mappings_indirect_supported() false
#endif

// Global initialization/exit functions, that need to be called during driver
// initialization/tear-down. These are needed to allocate/free global internal
// data structures.
NV_STATUS uvm_pmm_sysmem_init(void);
void uvm_pmm_sysmem_exit(void);

// Initialize per-GPU sysmem mapping tracking
NV_STATUS uvm_pmm_sysmem_mappings_init(uvm_gpu_t *gpu, uvm_pmm_sysmem_mappings_t *sysmem_mappings);

// Destroy per-GPU sysmem mapping tracking. The caller must ensure that all the
// mappings have been removed before calling this function.
void uvm_pmm_sysmem_mappings_deinit(uvm_pmm_sysmem_mappings_t *sysmem_mappings);

// If the GPU used to initialize sysmem_mappings supports access counters, the
// dma_addr -> {va_block, virt_addr} mapping is inserted in the reverse map.
NV_STATUS uvm_pmm_sysmem_mappings_add_gpu_mapping(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                                  NvU64 dma_addr,
                                                  NvU64 virt_addr,
                                                  NvU64 region_size,
                                                  uvm_va_block_t *va_block,
                                                  uvm_processor_id_t owner);

static NV_STATUS uvm_pmm_sysmem_mappings_add_gpu_chunk_mapping(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                                               NvU64 dma_addr,
                                                               NvU64 virt_addr,
                                                               NvU64 region_size,
                                                               uvm_va_block_t *va_block,
                                                               uvm_gpu_id_t owner)
{
    if (!uvm_pmm_sysmem_mappings_indirect_supported())
        return NV_OK;

    return uvm_pmm_sysmem_mappings_add_gpu_mapping(sysmem_mappings,
                                                   dma_addr,
                                                   virt_addr,
                                                   region_size,
                                                   va_block,
                                                   owner);
}

// If the GPU used to initialize sysmem_mappings supports access counters, the
// entries for the physical region starting at dma_addr are removed from the
// reverse map.
void uvm_pmm_sysmem_mappings_remove_gpu_mapping(uvm_pmm_sysmem_mappings_t *sysmem_mappings, NvU64 dma_addr);

static void uvm_pmm_sysmem_mappings_remove_gpu_chunk_mapping(uvm_pmm_sysmem_mappings_t *sysmem_mappings, NvU64 dma_addr)
{
    if (uvm_pmm_sysmem_mappings_indirect_supported())
        uvm_pmm_sysmem_mappings_remove_gpu_mapping(sysmem_mappings, dma_addr);
}

// Like uvm_pmm_sysmem_mappings_remove_gpu_mapping but it doesn't assert if the
// mapping doesn't exist. See uvm_va_block_evict_chunks for more information.
void uvm_pmm_sysmem_mappings_remove_gpu_mapping_on_eviction(uvm_pmm_sysmem_mappings_t *sysmem_mappings, NvU64 dma_addr);

// If the GPU used to initialize sysmem_mappings supports access counters, the
// mapping for the region starting at dma_addr is updated with va_block.
// This is required on VA block split.
void uvm_pmm_sysmem_mappings_reparent_gpu_mapping(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                                  NvU64 dma_addr,
                                                  uvm_va_block_t *va_block);

static void uvm_pmm_sysmem_mappings_reparent_gpu_chunk_mapping(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                                               NvU64 dma_addr,
                                                               uvm_va_block_t *va_block)
{
    if (uvm_pmm_sysmem_mappings_indirect_supported())
        uvm_pmm_sysmem_mappings_reparent_gpu_mapping(sysmem_mappings, dma_addr, va_block);
}

// If the GPU used to initialize sysmem_mappings supports access counters, the
// mapping for the region starting at dma_addr is split into regions of
// new_region_size. new_region_size must be a power of two and smaller than the
// previously-registered size.
NV_STATUS uvm_pmm_sysmem_mappings_split_gpu_mappings(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                                     NvU64 dma_addr,
                                                     NvU64 new_region_size);

static NV_STATUS uvm_pmm_sysmem_mappings_split_gpu_chunk_mappings(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                                                  NvU64 dma_addr,
                                                                  NvU64 new_region_size)
{
    if (!uvm_pmm_sysmem_mappings_indirect_supported())
        return NV_OK;

    return uvm_pmm_sysmem_mappings_split_gpu_mappings(sysmem_mappings, dma_addr, new_region_size);
}

// If the GPU used to initialize sysmem_mappings supports access counters, all
// the mappings within the region [dma_addr, dma_addr + new_region_size) are
// merged into a single mapping. new_region_size must be a power of two. The
// whole region must be previously populated with mappings and all of them must
// have the same VA block and processor owner.
void uvm_pmm_sysmem_mappings_merge_gpu_mappings(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                                NvU64 dma_addr,
                                                NvU64 new_region_size);

static void uvm_pmm_sysmem_mappings_merge_gpu_chunk_mappings(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                                             NvU64 dma_addr,
                                                             NvU64 new_region_size)
{
    if (uvm_pmm_sysmem_mappings_indirect_supported())
        uvm_pmm_sysmem_mappings_merge_gpu_mappings(sysmem_mappings, dma_addr, new_region_size);
}

// Obtain the {va_block, virt_addr} information for the mappings in the given
// [dma_addr:dma_addr + region_size) range. dma_addr and region_size must be
// page-aligned.
//
// Valid translations are written to out_mappings sequentially (there are no
// gaps). max_out_mappings are written, at most. The caller is required to
// provide enough entries in out_mappings.
//
// The VA Block in each returned translation entry is retained, and it's up to
// the caller to release them
size_t uvm_pmm_sysmem_mappings_dma_to_virt(uvm_pmm_sysmem_mappings_t *sysmem_mappings,
                                           NvU64 dma_addr,
                                           NvU64 region_size,
                                           uvm_reverse_map_t *out_mappings,
                                           size_t max_out_mappings);

#define UVM_CPU_CHUNK_SIZES (UVM_PAGE_SIZE_2M | UVM_PAGE_SIZE_64K | PAGE_SIZE)

typedef enum
{
    UVM_CPU_CHUNK_ALLOC_FLAGS_NONE = 0,

    // Zero the chunk.
    UVM_CPU_CHUNK_ALLOC_FLAGS_ZERO = (1 << 0),

    // Account for the chunk in the cgroup context.
    UVM_CPU_CHUNK_ALLOC_FLAGS_ACCOUNT = (1 << 1),
} uvm_cpu_chunk_alloc_flags_t;

typedef enum
{
    UVM_CPU_CHUNK_TYPE_PHYSICAL,
    UVM_CPU_CHUNK_TYPE_LOGICAL,
    UVM_CPU_CHUNK_TYPE_HMM
} uvm_cpu_chunk_type_t;

// CPU memory chunk descriptor.
// CPU memory chunks represent a physically contiguous CPU memory
// allocation.
// CPU memory chunks can be created due to CPU page allocation or
// CPU chunk splitting. Chunks created due to page allocations are
// referred to as "physical chunks", while chunks resulting from
// splitting are referred to as "logical chunks".
struct uvm_cpu_chunk_struct
{
    uvm_cpu_chunk_type_t type:2;

    // Size of the chunk.
    // For chunks resulting from page allocations (physical chunks),
    // this value is the size of the physical allocation.
    size_t log2_size : order_base_2(UVM_CHUNK_SIZE_MASK_SIZE);

    // Chunk reference count used when a CPU chunk is split. Each
    // child sub-chunk will increment the reference count of its
    // parent.
    // The reference count is set to 1 when the chunk is created.
    // This initial reference is dropped if the chunk is split in
    // order to automatically destroy the chunk when all logical
    // chunks resulting from the split are destroyed.
    nv_kref_t refcount;

    // Pointer to the CPU page backing this CPU chunk.
    // For physical chunks, this will point to the head page. Physical
    // chunk allocation will set the reference count for the struct
    // page (compound or not) to 1.
    //
    // For logical chunks, this will point to the struct page from
    // the compound page array corresponding to the correct page index.
    // Because freeing a logical chunk does not result in freeing of
    // any struct page(s) and both physical and logical chunks are
    // reference counted, there is no need to take separate references
    // to the struct page for logical chunks.
    struct page *page;
};

typedef struct
{
    NvU64 dma_addr;
    NvU32 map_count;
} uvm_cpu_phys_mapping_t;

typedef struct
{
    uvm_cpu_chunk_t common;

    // Lock protecting dirty_bitmap and gpu_mappings.
    uvm_mutex_t lock;

    struct
    {
        // Per-GPU array of DMA mapping addresses for the chunk.
        // The DMA mapping addresses for logical chunks are adjusted
        // to the correct offset within the parent chunk.
        union
        {
            uvm_cpu_phys_mapping_t static_entry;
            uvm_cpu_phys_mapping_t *dynamic_entries;
        };

        // Miximum number of physical mapping entries available.
        // The initial value is 1 since the static_entry is always
        // available.
        // When using the dynamic_entries, it holds the size of the
        // dynamic_entries array. This may be more than the number
        // of GPUs with active mappings. The number of active entries
        // is the number of set bits in dma_addrs_mask.
        size_t max_entries;

        // The set of GPU ID's that have an active physical mapping.
        // Since physical mappings are shared by all GPUs under a
        // parent GPU, this mask only needs to track uvm_parent_gpu_t.
        uvm_processor_mask_t dma_addrs_mask;
    } gpu_mappings;

    // A dynamically allocated bitmap (one per PAGE_SIZE page) used
    // to track dirty state of each PAGE_SIZE page.
    // Large CPU chunks are allocated as compound pages. For such
    // pages, the kernel keeps dirtiness state with a single bit
    // (in the compound page head) that covers the entire compound
    // page.
    //
    // In the case of UVM-Lite GPUs, using the dirty bit of the
    // the compound page will cause performance regression due to
    // the copying of extra data. We mitigate this by using this
    // bitmap to track which base pages are dirty.
    unsigned long *dirty_bitmap;

} uvm_cpu_physical_chunk_t;

typedef struct
{
    uvm_cpu_chunk_t common;

    // Pointer to the parent chunk (which could also be a logical chunk).
    uvm_cpu_chunk_t *parent;
    uvm_processor_mask_t mapped_gpus;
} uvm_cpu_logical_chunk_t;

// Return the set of allowed CPU chunk allocation sizes.
uvm_chunk_sizes_mask_t uvm_cpu_chunk_get_allocation_sizes(void);

// Allocate a physical CPU chunk of the specified size.
//
// If a CPU chunk allocation succeeds, NV_OK is returned. new_chunk will be set
// to point to the newly allocated chunk. On failure, NV_ERR_NO_MEMORY is
// returned.
NV_STATUS uvm_cpu_chunk_alloc(uvm_chunk_size_t alloc_size,
                              uvm_cpu_chunk_alloc_flags_t flags,
                              uvm_cpu_chunk_t **new_chunk);

// Allocate a HMM CPU chunk.
//
// HMM chunks differ from normal CPU chunks in that the kernel has already
// allocated the page for them. This means we don't allocate any CPU memory
// here. It also means the kernel holds the reference to the page, so we
// shouldn't call put_page() when freeing the chunk.
//
// If a CPU chunk allocation succeeds NV_OK is returned and new_chunk will be
// set to point to the newly allocated chunk. On failure, NV_ERR_NO_MEMORY is
// returned.
//
// Note that the kernel retains logical ownership of the page. This means page
// properties should not be directly modified by UVM. In particular page flags
// such as PageDirty should not be modified by UVM, nor can UVM directly free
// the page. The kernel is also responsible for mapping/unmapping the page on
// the CPU. We create a CPU chunk for the page primarily to allow GPU mappings
// for the page to be created.
NV_STATUS uvm_cpu_chunk_alloc_hmm(struct page *page,
                                  uvm_cpu_chunk_t **new_chunk);

// Convert a physical chunk to an HMM chunk.
static void uvm_cpu_chunk_make_hmm(uvm_cpu_chunk_t *chunk)
{
    UVM_ASSERT(chunk->type == UVM_CPU_CHUNK_TYPE_PHYSICAL);

    chunk->type = UVM_CPU_CHUNK_TYPE_HMM;
}

uvm_chunk_size_t uvm_cpu_chunk_get_size(uvm_cpu_chunk_t *chunk);

// Return the number of base system pages covered by the CPU chunk.
static size_t uvm_cpu_chunk_num_pages(uvm_cpu_chunk_t *chunk)
{
    UVM_ASSERT(chunk);
    return uvm_cpu_chunk_get_size(chunk) / PAGE_SIZE;
}

static inline bool uvm_cpu_chunk_is_hmm(uvm_cpu_chunk_t *chunk)
{
    return chunk->type == UVM_CPU_CHUNK_TYPE_HMM;
}

static bool uvm_cpu_chunk_is_physical(uvm_cpu_chunk_t *chunk)
{
    return (chunk->type == UVM_CPU_CHUNK_TYPE_PHYSICAL || uvm_cpu_chunk_is_hmm(chunk));
}

static bool uvm_cpu_chunk_is_logical(uvm_cpu_chunk_t *chunk)
{
    return chunk->type == UVM_CPU_CHUNK_TYPE_LOGICAL;
}

static uvm_cpu_physical_chunk_t *uvm_cpu_chunk_to_physical(uvm_cpu_chunk_t *chunk)
{
    UVM_ASSERT(uvm_cpu_chunk_is_physical(chunk));
    return container_of((chunk), uvm_cpu_physical_chunk_t, common);
}

static uvm_cpu_logical_chunk_t *uvm_cpu_chunk_to_logical(uvm_cpu_chunk_t *chunk)
{
    UVM_ASSERT(uvm_cpu_chunk_is_logical(chunk));
    return container_of((chunk), uvm_cpu_logical_chunk_t, common);
}

// Free a CPU chunk.
// This may not result in the immediate freeing of the physical pages of the
// chunk if this is a logical chunk and there are other logical chunks holding
// references to the physical chunk.
// If any DMA mappings to this chunk are still active, they are implicitly
// destroyed.
void uvm_cpu_chunk_free(uvm_cpu_chunk_t *chunk);

// In some configurations such as SR-IOV heavy, a CPU chunk cannot be
// referenced using its physical address. There needs to be a kernel virtual
// mapping created.
//
// This helper function creates a DMA mapping on the GPU (see
// uvm_cpu_chunk_map_gpu()) and if necessary a kernel virtual mapping for the
// chunk. The virtual mapping persists until GPU deinitialization, such that no
// unmap functionality is exposed. For more details see uvm_mmu_sysmem_map().
//
// Note that unlike uvm_cpu_chunk_map_gpu(), this helper requires the GPU
// object instead of the parent GPU object.
NV_STATUS uvm_cpu_chunk_map_gpu(uvm_cpu_chunk_t *chunk, uvm_gpu_t *gpu);

// Destroy a CPU chunk's DMA mapping for the parent GPU.
// If chunk is a logical chunk, this call may not necessary destroy the DMA
// mapping of the parent physical chunk since all logical chunks share the
// parent's DMA mapping.
void uvm_cpu_chunk_unmap_gpu_phys(uvm_cpu_chunk_t *chunk, uvm_parent_gpu_t *parent_gpu);

// Get the CPU chunk's DMA mapping address for the specified GPU ID.
// If there is no mapping for the GPU, 0 is returned.
NvU64 uvm_cpu_chunk_get_gpu_phys_addr(uvm_cpu_chunk_t *chunk, uvm_parent_gpu_t *parent_gpu);

// Split a CPU chunk into a set of CPU chunks of the next size down from the set
// of enabled CPU chunk sizes.
//
// This function expects that the chunk to be split is larger than the minimum
// enabled chunk size and that new_chunks has enough space for all chunks
// resulting from the split.
//
// On success, NV_OK is returned and the caller-provided new_chunks array will
// be filled out with the newly-created logical chunks.
//
// After a successfull split, the input chunk can no longer be used.
//
// On failure NV_ERR_NO_MEMORY will be returned.
//
// Should never be called for HMM chunks as these don't need splitting (they can
// only be PAGE_SIZE) and even if larger chunks could exist UVM could not split
// them without kernel interaction which currently isn't exported. Will return
// NV_ERR_INVALID_ARGUMENT for a HMM chunk.
// TODO: Bug 3368756: add support for transparent huge page (THP)
NV_STATUS uvm_cpu_chunk_split(uvm_cpu_chunk_t *chunk, uvm_cpu_chunk_t **new_chunks);

// Merge an array of logical chunks into their parent chunk. All chunks have to
// have the same size, parent, and set of mapped GPUs.
uvm_cpu_chunk_t *uvm_cpu_chunk_merge(uvm_cpu_chunk_t **chunks);

// Mark the page_index sub-page of the chunk as dirty.
// page_index is an offset into the chunk.
//
// Note that dirty status for HMM chunks should not be modified directly from
// UVM. Instead the kernel will mark the backing struct pages dirty either on
// fault when written to from the CPU, or when the PTE is mirrored to the GPU
// using hmm_range_fault().
void uvm_cpu_chunk_mark_dirty(uvm_cpu_chunk_t *chunk, uvm_page_index_t page_index);

// Mark the page_index sub-page of the chunk as clean.
// page_index is an offset into the chunk.
void uvm_cpu_chunk_mark_clean(uvm_cpu_chunk_t *chunk, uvm_page_index_t page_index);

// Return true if the page_index base page of the CPU chunk is dirty.
bool uvm_cpu_chunk_is_dirty(uvm_cpu_chunk_t *chunk, uvm_page_index_t page_index);

static NV_STATUS uvm_test_get_cpu_chunk_allocation_sizes(UVM_TEST_GET_CPU_CHUNK_ALLOC_SIZES_PARAMS *params,
                                                                struct file *filp)
{
        params->alloc_size_mask = (NvU32)uvm_cpu_chunk_get_allocation_sizes();
        return NV_OK;
}
#endif