mirror of
https://github.com/NVIDIA/open-gpu-kernel-modules.git
synced 2024-12-12 21:08:56 +01:00
560 lines
19 KiB
C
560 lines
19 KiB
C
/*******************************************************************************
|
|
Copyright (c) 2015 NVIDIA Corporation
|
|
|
|
Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
of this software and associated documentation files (the "Software"), to
|
|
deal in the Software without restriction, including without limitation the
|
|
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
|
|
sell copies of the Software, and to permit persons to whom the Software is
|
|
furnished to do so, subject to the following conditions:
|
|
|
|
The above copyright notice and this permission notice shall be
|
|
included in all copies or substantial portions of the Software.
|
|
|
|
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
|
|
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
|
|
DEALINGS IN THE SOFTWARE.
|
|
|
|
*******************************************************************************/
|
|
|
|
#include "uvm_gpu_semaphore.h"
|
|
#include "uvm_lock.h"
|
|
#include "uvm_global.h"
|
|
#include "uvm_kvmalloc.h"
|
|
#include "uvm_channel.h" // For UVM_GPU_SEMAPHORE_MAX_JUMP
|
|
|
|
#define UVM_SEMAPHORE_SIZE 4
|
|
#define UVM_SEMAPHORE_PAGE_SIZE PAGE_SIZE
|
|
#define UVM_SEMAPHORE_COUNT_PER_PAGE (PAGE_SIZE / UVM_SEMAPHORE_SIZE)
|
|
|
|
// The top nibble of the canary base is intentionally 0. The rest of the value
|
|
// is arbitrary. See the comments below on make_canary.
|
|
#define UVM_SEMAPHORE_CANARY_BASE 0x0badc0de
|
|
#define UVM_SEMAPHORE_CANARY_MASK 0xf0000000
|
|
|
|
struct uvm_gpu_semaphore_pool_struct
|
|
{
|
|
// The GPU owning the pool
|
|
uvm_gpu_t *gpu;
|
|
|
|
// List of all the semaphore pages belonging to the pool
|
|
struct list_head pages;
|
|
|
|
// Count of free semaphores among all the pages
|
|
NvU32 free_semaphores_count;
|
|
|
|
// Lock protecting the state of the pool
|
|
uvm_mutex_t mutex;
|
|
};
|
|
|
|
struct uvm_gpu_semaphore_pool_page_struct
|
|
{
|
|
// Allocation backing the page
|
|
uvm_rm_mem_t *memory;
|
|
|
|
// Pool the page is part of
|
|
uvm_gpu_semaphore_pool_t *pool;
|
|
|
|
// Node in the list of all pages in a semaphore pool
|
|
struct list_head all_pages_node;
|
|
|
|
// Mask indicating free semaphore indices within the page
|
|
DECLARE_BITMAP(free_semaphores, UVM_SEMAPHORE_COUNT_PER_PAGE);
|
|
};
|
|
|
|
static NvU32 get_index(uvm_gpu_semaphore_t *semaphore)
|
|
{
|
|
NvU32 offset;
|
|
NvU32 index;
|
|
|
|
UVM_ASSERT(semaphore->payload != NULL);
|
|
UVM_ASSERT(semaphore->page != NULL);
|
|
|
|
offset = (char*)semaphore->payload - (char*)uvm_rm_mem_get_cpu_va(semaphore->page->memory);
|
|
UVM_ASSERT(offset % UVM_SEMAPHORE_SIZE == 0);
|
|
|
|
index = offset / UVM_SEMAPHORE_SIZE;
|
|
UVM_ASSERT(index < UVM_SEMAPHORE_COUNT_PER_PAGE);
|
|
|
|
return index;
|
|
}
|
|
|
|
// Use canary values on debug builds to catch semaphore use-after-free. We can
|
|
// catch release-after-free by simply setting the payload to a known value at
|
|
// free then checking it on alloc or pool free, but catching acquire-after-free
|
|
// is a little trickier.
|
|
//
|
|
// In order to make still-pending GEQ acquires stall indefinitely we need to
|
|
// reduce the current payload as much as we can, subject to two restrictions:
|
|
//
|
|
// 1) The pending acquires could be comparing against values much less than and
|
|
// much greater than the current payload, so we have to set the payload to a
|
|
// value reasonably less than the acquires which we might expect to be
|
|
// pending.
|
|
//
|
|
// 2) Going over halfway past a pending acquire on the 32-bit number wheel will
|
|
// cause Host to wrap and think the acquire succeeded. So we shouldn't reduce
|
|
// by more than 2^31.
|
|
//
|
|
// To handle these restrictions we'll deal with quadrants of 2^32, under the
|
|
// assumption that it's unlikely for a payload to outpace a pending acquire by
|
|
// more than 2^30.
|
|
//
|
|
// We also need for the base value to have some 0s in the upper significant
|
|
// bits, otherwise those bits might carry us past the quadrant boundary when we
|
|
// OR them in.
|
|
static NvU32 make_canary(NvU32 payload)
|
|
{
|
|
NvU32 prev_quadrant = payload - (1 << 30);
|
|
return (prev_quadrant & UVM_SEMAPHORE_CANARY_MASK) | UVM_SEMAPHORE_CANARY_BASE;
|
|
}
|
|
|
|
static bool is_canary(NvU32 val)
|
|
{
|
|
return (val & ~UVM_SEMAPHORE_CANARY_MASK) == UVM_SEMAPHORE_CANARY_BASE;
|
|
}
|
|
|
|
static NV_STATUS pool_alloc_page(uvm_gpu_semaphore_pool_t *pool)
|
|
{
|
|
NV_STATUS status;
|
|
uvm_gpu_semaphore_pool_page_t *pool_page;
|
|
NvU32 *payloads;
|
|
size_t i;
|
|
|
|
uvm_assert_mutex_locked(&pool->mutex);
|
|
|
|
pool_page = uvm_kvmalloc_zero(sizeof(*pool_page));
|
|
|
|
if (!pool_page)
|
|
return NV_ERR_NO_MEMORY;
|
|
|
|
pool_page->pool = pool;
|
|
|
|
status = uvm_rm_mem_alloc_and_map_all(pool->gpu, UVM_RM_MEM_TYPE_SYS, UVM_SEMAPHORE_PAGE_SIZE, &pool_page->memory);
|
|
if (status != NV_OK)
|
|
goto error;
|
|
|
|
// All semaphores are initially free
|
|
bitmap_fill(pool_page->free_semaphores, UVM_SEMAPHORE_COUNT_PER_PAGE);
|
|
|
|
list_add(&pool_page->all_pages_node, &pool->pages);
|
|
pool->free_semaphores_count += UVM_SEMAPHORE_COUNT_PER_PAGE;
|
|
|
|
// Initialize the semaphore payloads to known values
|
|
if (UVM_IS_DEBUG()) {
|
|
payloads = uvm_rm_mem_get_cpu_va(pool_page->memory);
|
|
for (i = 0; i < UVM_SEMAPHORE_COUNT_PER_PAGE; i++)
|
|
payloads[i] = make_canary(0);
|
|
}
|
|
|
|
return NV_OK;
|
|
|
|
error:
|
|
uvm_kvfree(pool_page);
|
|
return status;
|
|
}
|
|
|
|
static void pool_free_page(uvm_gpu_semaphore_pool_page_t *page)
|
|
{
|
|
uvm_gpu_semaphore_pool_t *pool;
|
|
NvU32 *payloads;
|
|
size_t i;
|
|
|
|
UVM_ASSERT(page);
|
|
pool = page->pool;
|
|
|
|
uvm_assert_mutex_locked(&pool->mutex);
|
|
|
|
// Assert that no semaphores are still allocated
|
|
UVM_ASSERT(bitmap_full(page->free_semaphores, UVM_SEMAPHORE_COUNT_PER_PAGE));
|
|
UVM_ASSERT_MSG(pool->free_semaphores_count >= UVM_SEMAPHORE_COUNT_PER_PAGE,
|
|
"count: %u\n",
|
|
pool->free_semaphores_count);
|
|
|
|
// Check for semaphore release-after-free
|
|
if (UVM_IS_DEBUG()) {
|
|
payloads = uvm_rm_mem_get_cpu_va(page->memory);
|
|
for (i = 0; i < UVM_SEMAPHORE_COUNT_PER_PAGE; i++)
|
|
UVM_ASSERT(is_canary(payloads[i]));
|
|
}
|
|
|
|
pool->free_semaphores_count -= UVM_SEMAPHORE_COUNT_PER_PAGE;
|
|
list_del(&page->all_pages_node);
|
|
uvm_rm_mem_free(page->memory);
|
|
uvm_kvfree(page);
|
|
}
|
|
|
|
NV_STATUS uvm_gpu_semaphore_alloc(uvm_gpu_semaphore_pool_t *pool, uvm_gpu_semaphore_t *semaphore)
|
|
{
|
|
NV_STATUS status = NV_OK;
|
|
uvm_gpu_semaphore_pool_page_t *page;
|
|
|
|
memset(semaphore, 0, sizeof(*semaphore));
|
|
|
|
uvm_mutex_lock(&pool->mutex);
|
|
|
|
if (pool->free_semaphores_count == 0)
|
|
status = pool_alloc_page(pool);
|
|
|
|
if (status != NV_OK)
|
|
goto done;
|
|
|
|
list_for_each_entry(page, &pool->pages, all_pages_node) {
|
|
NvU32 semaphore_index = find_first_bit(page->free_semaphores, UVM_SEMAPHORE_COUNT_PER_PAGE);
|
|
if (semaphore_index == UVM_SEMAPHORE_COUNT_PER_PAGE)
|
|
continue;
|
|
|
|
semaphore->payload = (NvU32*)((char*)uvm_rm_mem_get_cpu_va(page->memory) + semaphore_index * UVM_SEMAPHORE_SIZE);
|
|
semaphore->page = page;
|
|
|
|
// Check for semaphore release-after-free
|
|
UVM_ASSERT(is_canary(uvm_gpu_semaphore_get_payload(semaphore)));
|
|
|
|
uvm_gpu_semaphore_set_payload(semaphore, 0);
|
|
|
|
__clear_bit(semaphore_index, page->free_semaphores);
|
|
--pool->free_semaphores_count;
|
|
|
|
goto done;
|
|
}
|
|
|
|
UVM_ASSERT_MSG(0, "Failed to find a semaphore after allocating a new page\n");
|
|
status = NV_ERR_GENERIC;
|
|
|
|
done:
|
|
uvm_mutex_unlock(&pool->mutex);
|
|
|
|
return status;
|
|
}
|
|
|
|
void uvm_gpu_semaphore_free(uvm_gpu_semaphore_t *semaphore)
|
|
{
|
|
uvm_gpu_semaphore_pool_page_t *page;
|
|
uvm_gpu_semaphore_pool_t *pool;
|
|
NvU32 index;
|
|
|
|
UVM_ASSERT(semaphore);
|
|
|
|
// uvm_gpu_semaphore_t is to be embedded in other structures so it should always
|
|
// be accessible, but it may not be initialized in error cases. Early out if
|
|
// page is NULL indicating the semaphore hasn't been allocated successfully.
|
|
page = semaphore->page;
|
|
if (page == NULL)
|
|
return;
|
|
|
|
pool = page->pool;
|
|
index = get_index(semaphore);
|
|
|
|
// Write a known value lower than the current payload in an attempt to catch
|
|
// release-after-free and acquire-after-free.
|
|
if (UVM_IS_DEBUG())
|
|
uvm_gpu_semaphore_set_payload(semaphore, make_canary(uvm_gpu_semaphore_get_payload(semaphore)));
|
|
|
|
uvm_mutex_lock(&pool->mutex);
|
|
|
|
semaphore->page = NULL;
|
|
semaphore->payload = NULL;
|
|
|
|
++pool->free_semaphores_count;
|
|
__set_bit(index, page->free_semaphores);
|
|
|
|
uvm_mutex_unlock(&pool->mutex);
|
|
}
|
|
|
|
NV_STATUS uvm_gpu_semaphore_pool_create(uvm_gpu_t *gpu, uvm_gpu_semaphore_pool_t **pool_out)
|
|
{
|
|
uvm_gpu_semaphore_pool_t *pool;
|
|
pool = uvm_kvmalloc_zero(sizeof(*pool));
|
|
|
|
if (!pool)
|
|
return NV_ERR_NO_MEMORY;
|
|
|
|
uvm_mutex_init(&pool->mutex, UVM_LOCK_ORDER_GPU_SEMAPHORE_POOL);
|
|
|
|
INIT_LIST_HEAD(&pool->pages);
|
|
|
|
pool->free_semaphores_count = 0;
|
|
pool->gpu = gpu;
|
|
|
|
*pool_out = pool;
|
|
|
|
return NV_OK;
|
|
}
|
|
|
|
void uvm_gpu_semaphore_pool_destroy(uvm_gpu_semaphore_pool_t *pool)
|
|
{
|
|
uvm_gpu_semaphore_pool_page_t *page;
|
|
uvm_gpu_semaphore_pool_page_t *next_page;
|
|
|
|
if (!pool)
|
|
return;
|
|
|
|
// No other thread should be touching the pool once it's being destroyed
|
|
uvm_assert_mutex_unlocked(&pool->mutex);
|
|
|
|
// Keep pool_free_page happy
|
|
uvm_mutex_lock(&pool->mutex);
|
|
|
|
list_for_each_entry_safe(page, next_page, &pool->pages, all_pages_node)
|
|
pool_free_page(page);
|
|
|
|
UVM_ASSERT_MSG(pool->free_semaphores_count == 0, "unused: %u", pool->free_semaphores_count);
|
|
UVM_ASSERT(list_empty(&pool->pages));
|
|
|
|
uvm_mutex_unlock(&pool->mutex);
|
|
|
|
uvm_kvfree(pool);
|
|
}
|
|
|
|
NV_STATUS uvm_gpu_semaphore_pool_map_gpu(uvm_gpu_semaphore_pool_t *pool, uvm_gpu_t *gpu)
|
|
{
|
|
NV_STATUS status = NV_OK;
|
|
uvm_gpu_semaphore_pool_page_t *page;
|
|
|
|
UVM_ASSERT(pool);
|
|
UVM_ASSERT(gpu);
|
|
|
|
uvm_mutex_lock(&pool->mutex);
|
|
|
|
list_for_each_entry(page, &pool->pages, all_pages_node) {
|
|
status = uvm_rm_mem_map_gpu(page->memory, gpu);
|
|
if (status != NV_OK)
|
|
goto done;
|
|
}
|
|
|
|
done:
|
|
uvm_mutex_unlock(&pool->mutex);
|
|
|
|
return status;
|
|
}
|
|
|
|
void uvm_gpu_semaphore_pool_unmap_gpu(uvm_gpu_semaphore_pool_t *pool, uvm_gpu_t *gpu)
|
|
{
|
|
uvm_gpu_semaphore_pool_page_t *page;
|
|
|
|
UVM_ASSERT(pool);
|
|
UVM_ASSERT(gpu);
|
|
|
|
uvm_mutex_lock(&pool->mutex);
|
|
|
|
list_for_each_entry(page, &pool->pages, all_pages_node)
|
|
uvm_rm_mem_unmap_gpu(page->memory, gpu);
|
|
|
|
uvm_mutex_unlock(&pool->mutex);
|
|
}
|
|
|
|
NvU64 uvm_gpu_semaphore_get_gpu_uvm_va(uvm_gpu_semaphore_t *semaphore, uvm_gpu_t *gpu)
|
|
{
|
|
return uvm_gpu_semaphore_get_gpu_va(semaphore, gpu, false);
|
|
}
|
|
|
|
NvU64 uvm_gpu_semaphore_get_gpu_proxy_va(uvm_gpu_semaphore_t *semaphore, uvm_gpu_t *gpu)
|
|
{
|
|
return uvm_gpu_semaphore_get_gpu_va(semaphore, gpu, true);
|
|
}
|
|
|
|
NvU64 uvm_gpu_semaphore_get_gpu_va(uvm_gpu_semaphore_t *semaphore, uvm_gpu_t *gpu, bool is_proxy_va_space)
|
|
{
|
|
NvU32 index = get_index(semaphore);
|
|
NvU64 base_va = uvm_rm_mem_get_gpu_va(semaphore->page->memory, gpu, is_proxy_va_space);
|
|
|
|
return base_va + UVM_SEMAPHORE_SIZE * index;
|
|
}
|
|
|
|
NvU32 uvm_gpu_semaphore_get_payload(uvm_gpu_semaphore_t *semaphore)
|
|
{
|
|
return UVM_GPU_READ_ONCE(*semaphore->payload);
|
|
}
|
|
|
|
void uvm_gpu_semaphore_set_payload(uvm_gpu_semaphore_t *semaphore, NvU32 payload)
|
|
{
|
|
// Provide a guarantee that all memory accesses prior to setting the payload
|
|
// won't be moved past it.
|
|
// Use a big hammer mb() as set_payload() is not used in any performance path
|
|
// today.
|
|
// This could likely be optimized to be either an smp_store_release() or use
|
|
// an smp_mb__before_atomic() barrier. The former is a recent addition to
|
|
// kernel though, and it's not clear whether combining the latter with a
|
|
// regular 32bit store is well defined in all cases. Both also seem to risk
|
|
// being optimized out on non-SMP configs (we need them for interacting with
|
|
// the GPU correctly even on non-SMP).
|
|
mb();
|
|
UVM_GPU_WRITE_ONCE(*semaphore->payload, payload);
|
|
}
|
|
|
|
// This function is intended to catch channels which have been left dangling in
|
|
// trackers after their owning GPUs have been destroyed.
|
|
static bool tracking_semaphore_check_gpu(uvm_gpu_tracking_semaphore_t *tracking_sem)
|
|
{
|
|
uvm_gpu_t *gpu = tracking_sem->semaphore.page->pool->gpu;
|
|
uvm_gpu_t *table_gpu;
|
|
|
|
UVM_ASSERT_MSG(gpu->magic == UVM_GPU_MAGIC_VALUE, "Corruption detected: magic number is 0x%llx\n", gpu->magic);
|
|
|
|
// It's ok for the GPU to not be in the global table, since add_gpu operates
|
|
// on trackers before adding the GPU to the table, and remove_gpu operates
|
|
// on trackers after removing the GPU. We rely on the magic value to catch
|
|
// those cases.
|
|
//
|
|
// But if a pointer is in the table it must match.
|
|
table_gpu = uvm_gpu_get(gpu->global_id);
|
|
if (table_gpu)
|
|
UVM_ASSERT(table_gpu == gpu);
|
|
|
|
// Return a boolean so this function can be used in assertions for
|
|
// conditional compilation
|
|
return true;
|
|
}
|
|
|
|
NV_STATUS uvm_gpu_tracking_semaphore_alloc(uvm_gpu_semaphore_pool_t *pool, uvm_gpu_tracking_semaphore_t *tracking_sem)
|
|
{
|
|
NV_STATUS status;
|
|
|
|
memset(tracking_sem, 0, sizeof(*tracking_sem));
|
|
|
|
status = uvm_gpu_semaphore_alloc(pool, &tracking_sem->semaphore);
|
|
if (status != NV_OK)
|
|
return status;
|
|
|
|
UVM_ASSERT(uvm_gpu_semaphore_get_payload(&tracking_sem->semaphore) == 0);
|
|
|
|
uvm_spin_lock_init(&tracking_sem->lock, UVM_LOCK_ORDER_LEAF);
|
|
atomic64_set(&tracking_sem->completed_value, 0);
|
|
tracking_sem->queued_value = 0;
|
|
|
|
return NV_OK;
|
|
}
|
|
|
|
void uvm_gpu_tracking_semaphore_free(uvm_gpu_tracking_semaphore_t *tracking_sem)
|
|
{
|
|
uvm_gpu_semaphore_free(&tracking_sem->semaphore);
|
|
}
|
|
|
|
static NvU64 update_completed_value_locked(uvm_gpu_tracking_semaphore_t *tracking_semaphore)
|
|
{
|
|
NvU64 old_value = atomic64_read(&tracking_semaphore->completed_value);
|
|
// The semaphore value is the bottom 32 bits of completed_value
|
|
NvU32 old_sem_value = (NvU32)old_value;
|
|
NvU32 new_sem_value = uvm_gpu_semaphore_get_payload(&tracking_semaphore->semaphore);
|
|
NvU64 new_value;
|
|
|
|
uvm_assert_spinlock_locked(&tracking_semaphore->lock);
|
|
|
|
// The following logic to update the completed value is very subtle, it
|
|
// helps to read https://www.kernel.org/doc/Documentation/memory-barriers.txt
|
|
// before going through this code.
|
|
|
|
if (old_sem_value == new_sem_value) {
|
|
// No progress since the last update.
|
|
// No additional memory barrier required in this case as completed_value
|
|
// is always updated under the spinlock that this thread just acquired.
|
|
// That guarantees full ordering with all the accesses the thread that
|
|
// updated completed_value did under the lock including the GPU
|
|
// semaphore read.
|
|
return old_value;
|
|
}
|
|
|
|
// Replace the bottom 32-bits with the new semaphore value
|
|
new_value = (old_value & 0xFFFFFFFF00000000ull) | new_sem_value;
|
|
|
|
// If we've wrapped around, add 2^32 to the value
|
|
// Notably the user of the GPU tracking semaphore needs to guarantee that
|
|
// the value is updated often enough to notice the wrap around each time it
|
|
// happens. In case of a channel tracking semaphore that's released for each
|
|
// push, it's easily guaranteed because of the small number of GPFIFO
|
|
// entries available per channel (there could be at most as many pending
|
|
// pushes as GPFIFO entries).
|
|
if (unlikely(new_sem_value < old_sem_value))
|
|
new_value += 1ULL << 32;
|
|
|
|
// Check for unexpected large jumps of the semaphore value
|
|
UVM_ASSERT_MSG_RELEASE(new_value - old_value <= UVM_GPU_SEMAPHORE_MAX_JUMP,
|
|
"GPU %s unexpected semaphore (CPU VA 0x%llx) jump from 0x%llx to 0x%llx\n",
|
|
tracking_semaphore->semaphore.page->pool->gpu->parent->name,
|
|
(NvU64)(uintptr_t)tracking_semaphore->semaphore.payload,
|
|
old_value, new_value);
|
|
|
|
// Use an atomic write even though the spinlock is held so that the value can
|
|
// be (carefully) read atomically outside of the lock.
|
|
//
|
|
// atomic64_set() on its own doesn't imply any memory barriers and we need
|
|
// prior memory accesses (in particular the read of the GPU semaphore
|
|
// payload) by this thread to be visible to other threads that see the newly
|
|
// set completed_value. smp_mb__before_atomic() provides that ordering.
|
|
//
|
|
// Also see the comment and matching smp_mb__after_atomic() barrier in
|
|
// uvm_gpu_tracking_semaphore_is_value_completed().
|
|
//
|
|
// Notably as of 4.3, atomic64_set_release() and atomic64_read_acquire()
|
|
// have been added that are exactly what we need and could be slightly
|
|
// faster on arm and powerpc than the implementation below. But at least in
|
|
// 4.3 the implementation looks broken for arm32 (it maps directly to
|
|
// smp_load_acquire() and that doesn't support 64-bit reads on 32-bit
|
|
// architectures) so instead of dealing with that just use a slightly bigger
|
|
// hammer.
|
|
smp_mb__before_atomic();
|
|
atomic64_set(&tracking_semaphore->completed_value, new_value);
|
|
|
|
// For this thread, we don't want any later accesses to be ordered above the
|
|
// GPU semaphore read. This could be accomplished by using a
|
|
// smp_load_acquire() for reading it, but given that it's also a pretty
|
|
// recent addition to the kernel, just leverage smp_mb__after_atomic() that
|
|
// guarantees that no accesses will be ordered above the atomic (and hence
|
|
// the GPU semaphore read).
|
|
//
|
|
// Notably the soon following uvm_spin_unlock() is a release barrier that
|
|
// allows later memory accesses to be reordered above it and hence doesn't
|
|
// provide the necessary ordering with the GPU semaphore read.
|
|
//
|
|
// Also notably this would still need to be handled if we ever switch to
|
|
// atomic64_set_release() and atomic64_read_acquire() for accessing
|
|
// completed_value.
|
|
smp_mb__after_atomic();
|
|
|
|
return new_value;
|
|
}
|
|
|
|
NvU64 uvm_gpu_tracking_semaphore_update_completed_value(uvm_gpu_tracking_semaphore_t *tracking_semaphore)
|
|
{
|
|
NvU64 completed;
|
|
|
|
// Check that the GPU which owns the semaphore is still present
|
|
UVM_ASSERT(tracking_semaphore_check_gpu(tracking_semaphore));
|
|
|
|
uvm_spin_lock(&tracking_semaphore->lock);
|
|
|
|
completed = update_completed_value_locked(tracking_semaphore);
|
|
|
|
uvm_spin_unlock(&tracking_semaphore->lock);
|
|
|
|
return completed;
|
|
}
|
|
|
|
bool uvm_gpu_tracking_semaphore_is_value_completed(uvm_gpu_tracking_semaphore_t *tracking_sem, NvU64 value)
|
|
{
|
|
NvU64 completed = atomic64_read(&tracking_sem->completed_value);
|
|
|
|
// Check that the GPU which owns the semaphore is still present
|
|
UVM_ASSERT(tracking_semaphore_check_gpu(tracking_sem));
|
|
|
|
if (completed >= value) {
|
|
// atomic64_read() doesn't imply any memory barriers and we need all
|
|
// subsequent memory accesses in this thread to be ordered after the
|
|
// atomic read of the completed value above as that will also order them
|
|
// with any accesses (in particular the GPU semaphore read) performed by
|
|
// the other thread prior to it setting the completed_value we read.
|
|
// smp_mb__after_atomic() provides that ordering.
|
|
//
|
|
// Also see the comment in update_completed_value_locked().
|
|
smp_mb__after_atomic();
|
|
|
|
return true;
|
|
}
|
|
|
|
return uvm_gpu_tracking_semaphore_update_completed_value(tracking_sem) >= value;
|
|
}
|