Add a helper function svm_populate_range to populate
a svm range. This functions calls hmm_range_fault
to read CPU page tables and populate all pfns of this
virtual address range into an array, saved in hmm_range::
hmm_pfns. This is prepare work to bind a svm range to
GPU. The hmm_pfns array will be used for the GPU binding.
Signed-off-by: Oak Zeng <oak.zeng@xxxxxxxxx>
Co-developed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx>
Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxx>
Cc: Brian Welty <brian.welty@xxxxxxxxx>
---
drivers/gpu/drm/xe/xe_svm.c | 61 +++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)
diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index 44d4f4216a93..0c13690a19f5 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -145,3 +145,64 @@ int xe_svm_build_sg(struct hmm_range *range,
sg_mark_end(sg);
return 0;
}
+
+/** Populate physical pages of a virtual address range
+ * This function also read mmu notifier sequence # (
+ * mmu_interval_read_begin), for the purpose of later
+ * comparison (through mmu_interval_read_retry).
+ * This must be called with mmap read or write lock held.
+ *
+ * This function alloates hmm_range->hmm_pfns, it is caller's
+ * responsibility to free it.
+ *
+ * @svm_range: The svm range to populate
+ * @hmm_range: pointer to hmm_range struct. hmm_rang->hmm_pfns
+ * will hold the populated pfns.
+ * @write: populate pages with write permission
+ *
+ * returns: 0 for succuss; negative error no on failure
+ */
+static int svm_populate_range(struct xe_svm_range *svm_range,
+ struct hmm_range *hmm_range, bool write)
+{
+ unsigned long timeout =
+ jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
+ unsigned long *pfns, flags = HMM_PFN_REQ_FAULT;
+ u64 npages;
+ int ret;
+
+ mmap_assert_locked(svm_range->svm->mm);
+
+ npages = ((svm_range->end - 1) >> PAGE_SHIFT) -
+ (svm_range->start >> PAGE_SHIFT) + 1;
+ pfns = kvmalloc_array(npages, sizeof(*pfns), GFP_KERNEL);
+ if (unlikely(!pfns))
+ return -ENOMEM;
+
+ if (write)
+ flags |= HMM_PFN_REQ_WRITE;
+
+ memset64((u64 *)pfns, (u64)flags, npages);
+ hmm_range->hmm_pfns = pfns;
+ hmm_range->notifier_seq = mmu_interval_read_begin(&svm_range->notifier);
+ hmm_range->notifier = &svm_range->notifier;
+ hmm_range->start = svm_range->start;
+ hmm_range->end = svm_range->end;
+ hmm_range->pfn_flags_mask = HMM_PFN_REQ_FAULT | HMM_PFN_REQ_WRITE;
+ hmm_range->dev_private_owner = svm_range->svm->vm->xe->drm.dev;
+
+ while (true) {
+ ret = hmm_range_fault(hmm_range);
+ if (time_after(jiffies, timeout))
+ goto free_pfns;
+
+ if (ret == -EBUSY)
+ continue;
+ break;
+ }
+
+free_pfns:
+ if (ret)
+ kvfree(pfns);
+ return ret;
+}
--
2.26.3
