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-rw-r--r--mm/hmm.c153
1 files changed, 138 insertions, 15 deletions
diff --git a/mm/hmm.c b/mm/hmm.c
index de032ff9e576..d37daf9edcd3 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -21,16 +21,27 @@
#include <linux/hmm.h>
#include <linux/slab.h>
#include <linux/sched.h>
+#include <linux/mmu_notifier.h>
#ifdef CONFIG_HMM
+static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
+
/*
* struct hmm - HMM per mm struct
*
* @mm: mm struct this HMM struct is bound to
+ * @sequence: we track updates to the CPU page table with a sequence number
+ * @mirrors: list of mirrors for this mm
+ * @mmu_notifier: mmu notifier to track updates to CPU page table
+ * @mirrors_sem: read/write semaphore protecting the mirrors list
*/
struct hmm {
struct mm_struct *mm;
+ atomic_t sequence;
+ struct list_head mirrors;
+ struct mmu_notifier mmu_notifier;
+ struct rw_semaphore mirrors_sem;
};
/*
@@ -43,27 +54,48 @@ struct hmm {
*/
static struct hmm *hmm_register(struct mm_struct *mm)
{
- if (!mm->hmm) {
- struct hmm *hmm = NULL;
-
- hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
- if (!hmm)
- return NULL;
- hmm->mm = mm;
-
- spin_lock(&mm->page_table_lock);
- if (!mm->hmm)
- mm->hmm = hmm;
- else
- kfree(hmm);
- spin_unlock(&mm->page_table_lock);
- }
+ struct hmm *hmm = READ_ONCE(mm->hmm);
+ bool cleanup = false;
/*
* The hmm struct can only be freed once the mm_struct goes away,
* hence we should always have pre-allocated an new hmm struct
* above.
*/
+ if (hmm)
+ return hmm;
+
+ hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
+ if (!hmm)
+ return NULL;
+ INIT_LIST_HEAD(&hmm->mirrors);
+ init_rwsem(&hmm->mirrors_sem);
+ atomic_set(&hmm->sequence, 0);
+ hmm->mmu_notifier.ops = NULL;
+ hmm->mm = mm;
+
+ /*
+ * We should only get here if hold the mmap_sem in write mode ie on
+ * registration of first mirror through hmm_mirror_register()
+ */
+ hmm->mmu_notifier.ops = &hmm_mmu_notifier_ops;
+ if (__mmu_notifier_register(&hmm->mmu_notifier, mm)) {
+ kfree(hmm);
+ return NULL;
+ }
+
+ spin_lock(&mm->page_table_lock);
+ if (!mm->hmm)
+ mm->hmm = hmm;
+ else
+ cleanup = true;
+ spin_unlock(&mm->page_table_lock);
+
+ if (cleanup) {
+ mmu_notifier_unregister(&hmm->mmu_notifier, mm);
+ kfree(hmm);
+ }
+
return mm->hmm;
}
@@ -72,3 +104,94 @@ void hmm_mm_destroy(struct mm_struct *mm)
kfree(mm->hmm);
}
#endif /* CONFIG_HMM */
+
+#if IS_ENABLED(CONFIG_HMM_MIRROR)
+static void hmm_invalidate_range(struct hmm *hmm,
+ enum hmm_update_type action,
+ unsigned long start,
+ unsigned long end)
+{
+ struct hmm_mirror *mirror;
+
+ down_read(&hmm->mirrors_sem);
+ list_for_each_entry(mirror, &hmm->mirrors, list)
+ mirror->ops->sync_cpu_device_pagetables(mirror, action,
+ start, end);
+ up_read(&hmm->mirrors_sem);
+}
+
+static void hmm_invalidate_range_start(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ struct hmm *hmm = mm->hmm;
+
+ VM_BUG_ON(!hmm);
+
+ atomic_inc(&hmm->sequence);
+}
+
+static void hmm_invalidate_range_end(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ struct hmm *hmm = mm->hmm;
+
+ VM_BUG_ON(!hmm);
+
+ hmm_invalidate_range(mm->hmm, HMM_UPDATE_INVALIDATE, start, end);
+}
+
+static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
+ .invalidate_range_start = hmm_invalidate_range_start,
+ .invalidate_range_end = hmm_invalidate_range_end,
+};
+
+/*
+ * hmm_mirror_register() - register a mirror against an mm
+ *
+ * @mirror: new mirror struct to register
+ * @mm: mm to register against
+ *
+ * To start mirroring a process address space, the device driver must register
+ * an HMM mirror struct.
+ *
+ * THE mm->mmap_sem MUST BE HELD IN WRITE MODE !
+ */
+int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm)
+{
+ /* Sanity check */
+ if (!mm || !mirror || !mirror->ops)
+ return -EINVAL;
+
+ mirror->hmm = hmm_register(mm);
+ if (!mirror->hmm)
+ return -ENOMEM;
+
+ down_write(&mirror->hmm->mirrors_sem);
+ list_add(&mirror->list, &mirror->hmm->mirrors);
+ up_write(&mirror->hmm->mirrors_sem);
+
+ return 0;
+}
+EXPORT_SYMBOL(hmm_mirror_register);
+
+/*
+ * hmm_mirror_unregister() - unregister a mirror
+ *
+ * @mirror: new mirror struct to register
+ *
+ * Stop mirroring a process address space, and cleanup.
+ */
+void hmm_mirror_unregister(struct hmm_mirror *mirror)
+{
+ struct hmm *hmm = mirror->hmm;
+
+ down_write(&hmm->mirrors_sem);
+ list_del(&mirror->list);
+ up_write(&hmm->mirrors_sem);
+}
+EXPORT_SYMBOL(hmm_mirror_unregister);
+#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */