Am 2021-04-22 um 10:47 a.m. schrieb Alex Sierra:
> SVM ranges are created for unregistered memory, triggered
> by page faults. These ranges are migrated/mapped to
> GPU VRAM memory.
>
> Signed-off-by: Alex Sierra <alex.sierra@xxxxxxx>
> ---
> drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 107 ++++++++++++++++++++++++++-
> 1 file changed, 104 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> index 45dd055118eb..44ff643e3c32 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> @@ -274,7 +274,7 @@ svm_range *svm_range_new(struct svm_range_list *svms, uint64_t start,
> INIT_LIST_HEAD(&prange->deferred_list);
> INIT_LIST_HEAD(&prange->child_list);
> atomic_set(&prange->invalid, 0);
> - prange->validate_timestamp = ktime_to_us(ktime_get());
> + prange->validate_timestamp = 0;
> mutex_init(&prange->migrate_mutex);
> mutex_init(&prange->lock);
> svm_range_set_default_attributes(&prange->preferred_loc,
> @@ -2179,6 +2179,86 @@ svm_range_best_restore_location(struct svm_range *prange,
>
> return -1;
> }
> +static int
> +svm_range_get_range_boundaries(struct kfd_process *p, int64_t addr,
> + unsigned long *start, unsigned long *last)
> +{
> + struct vm_area_struct *vma;
> + struct interval_tree_node *node;
> + unsigned long start_limit, end_limit;
> +
> + vma = find_vma(p->mm, addr << PAGE_SHIFT);
> + if (!vma || (addr << PAGE_SHIFT) < vma->vm_start) {
> + pr_debug("VMA does not exist in address [0x%llx]\n", addr);
> + return -EFAULT;
> + }
> + start_limit = max(vma->vm_start >> PAGE_SHIFT,
> + (unsigned long)ALIGN_DOWN(addr, 2UL << 8));
> + end_limit = min(vma->vm_end >> PAGE_SHIFT,
> + (unsigned long)ALIGN(addr + 1, 2UL << 8));
> + /* First range that starts after the fault address */
> + node = interval_tree_iter_first(&p->svms.objects, addr + 1, ULONG_MAX);
> + if (node) {
> + end_limit = min(end_limit, node->start);
> + /* Last range that ends before the fault address */
> + node = container_of(rb_prev(&node->rb),
> + struct interval_tree_node, rb);
> + } else {
> + /* Last range must end before addr because
> + * there was no range after addr
> + */
> + node = container_of(rb_last(&p->svms.objects.rb_root),
> + struct interval_tree_node, rb);
> + }
> + if (node) {
> + if (node->last >= addr) {
> + WARN(1, "Overlap with prev node and page fault addr\n");
> + return -EFAULT;
> + }
> + start_limit = max(start_limit, node->last + 1);
> + }
> +
> + *start = start_limit;
> + *last = end_limit - 1;
> +
> + pr_debug("vma start: 0x%lx start: 0x%lx vma end: 0x%lx last: 0x%lx\n",
> + vma->vm_start >> PAGE_SHIFT, *start,
> + vma->vm_end >> PAGE_SHIFT, *last);
> +
> + return 0;
> +
> +}
> +static struct
> +svm_range *svm_range_create_unregistered_range(struct amdgpu_device *adev,
> + struct kfd_process *p,
> + struct mm_struct *mm,
> + int64_t addr)
> +{
> + struct svm_range *prange = NULL;
> + unsigned long start, last;
> + uint32_t gpuid, gpuidx;
> +
> + if (svm_range_get_range_boundaries(p, addr, &start, &last))
> + return NULL;
> +
> + prange = svm_range_new(&p->svms, start, last);
> + if (!prange) {
> + pr_debug("Failed to create prange in address [0x%llx]\\n", addr);
> + return NULL;
> + }
> + if (kfd_process_gpuid_from_kgd(p, adev, &gpuid, &gpuidx)) {
> + pr_debug("failed to get gpuid from kgd\n");
> + svm_range_free(prange);
> + return NULL;
> + }
> + prange->preferred_loc = gpuid;
> + prange->actual_loc = 0;
> + /* Gurantee prange is migrate it */
> + svm_range_add_to_svms(prange);
> + svm_range_add_notifier_locked(mm, prange);
> +
> + return prange;
> +}
>
> /* svm_range_skip_recover - decide if prange can be recovered
> * @prange: svm range structure
> @@ -2228,6 +2308,7 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
> struct kfd_process *p;
> uint64_t timestamp;
> int32_t best_loc, gpuidx;
> + bool write_locked = false;
> int r = 0;
>
> p = kfd_lookup_process_by_pasid(pasid);
> @@ -2251,14 +2332,34 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
> }
>
> mmap_read_lock(mm);
> +retry_write_locked:
> mutex_lock(&svms->lock);
> prange = svm_range_from_addr(svms, addr, NULL);
> if (!prange) {
> pr_debug("failed to find prange svms 0x%p address [0x%llx]\n",
> svms, addr);
> - r = -EFAULT;
> - goto out_unlock_svms;
> + if (!write_locked) {
> + /* Need the write lock to create new range with MMU notifier.
> + * Also flush pending deferred work to make sure the interval
> + * tree is up to date before we add a new range
> + */
> + mutex_unlock(&svms->lock);
> + mmap_read_unlock(mm);
> + svm_range_list_lock_and_flush_work(svms, mm);
Replace svm_range_list_lock_and_flush with mmap_write_lock to avoid the
deadlock we discussed. With that fixed, the patch is
Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
> + write_locked = true;
> + goto retry_write_locked;
> + }
> + prange = svm_range_create_unregistered_range(adev, p, mm, addr);
> + if (!prange) {
> + pr_debug("failed to create unregisterd range svms 0x%p address [0x%llx]\n",
> + svms, addr);
> + mmap_write_downgrade(mm);
> + r = -EFAULT;
> + goto out_unlock_svms;
> + }
> }
> + if (write_locked)
> + mmap_write_downgrade(mm);
>
> mutex_lock(&prange->migrate_mutex);
>
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