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Subject[PATCH 12/36] HMM: add dirty range helper (to toggle dirty bit inside mirror page table).
Date
From: Jérôme Glisse <jglisse@redhat.com>

Device driver must properly toggle the dirty inside the mirror page table so
dirtyness is properly accounted when core mm code needs to know. Provide a
simple helper to toggle that bit for a range of address.

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
---
include/linux/hmm.h | 3 +++
mm/hmm.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 50 insertions(+)

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index ec05df8..186f497 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -253,6 +253,9 @@ int hmm_mirror_fault(struct hmm_mirror *mirror, struct hmm_event *event);
void hmm_mirror_range_discard(struct hmm_mirror *mirror,
unsigned long start,
unsigned long end);
+void hmm_mirror_range_dirty(struct hmm_mirror *mirror,
+ unsigned long start,
+ unsigned long end);


#endif /* CONFIG_HMM */
diff --git a/mm/hmm.c b/mm/hmm.c
index 4cab3f2..21fda9f 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -940,6 +940,53 @@ void hmm_mirror_range_discard(struct hmm_mirror *mirror,
}
EXPORT_SYMBOL(hmm_mirror_range_discard);

+/* hmm_mirror_range_dirty() - toggle dirty bit for a range of address.
+ *
+ * @mirror: The mirror struct.
+ * @start: Start address of the range to discard (inclusive).
+ * @end: End address of the range to discard (exclusive).
+ *
+ * Call when device driver want to toggle the dirty bit for a range of address.
+ * Usefull when the device driver just want to toggle the bit for whole range
+ * without walking the mirror page table itself.
+ *
+ * Note this function does not directly dirty the page behind an address, but
+ * this will happen once address is invalidated or discard by device driver or
+ * core mm code.
+ */
+void hmm_mirror_range_dirty(struct hmm_mirror *mirror,
+ unsigned long start,
+ unsigned long end)
+{
+ struct hmm_pt_iter iter;
+ unsigned long addr;
+
+ hmm_pt_iter_init(&iter);
+ for (addr = start; addr != end;) {
+ unsigned long cend, next;
+ dma_addr_t *hmm_pte;
+
+ hmm_pte = hmm_pt_iter_update(&iter, &mirror->pt, addr);
+ if (!hmm_pte) {
+ addr = hmm_pt_iter_next(&iter, &mirror->pt,
+ addr, end);
+ continue;
+ }
+ cend = hmm_pt_level_next(&mirror->pt, addr, end,
+ mirror->pt.llevel - 1);
+ do {
+ next = hmm_pt_level_next(&mirror->pt, addr, cend,
+ mirror->pt.llevel);
+ if (!hmm_pte_test_valid_pfn(hmm_pte) ||
+ !hmm_pte_test_write(hmm_pte))
+ continue;
+ hmm_pte_set_dirty(hmm_pte);
+ } while (addr = next, hmm_pte++, addr != cend);
+ }
+ hmm_pt_iter_fini(&iter, &mirror->pt);
+}
+EXPORT_SYMBOL(hmm_mirror_range_dirty);
+
/* hmm_mirror_register() - register mirror against current process for a device.
*
* @mirror: The mirror struct being registered.
--
1.9.3


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