On Fri, Jun 07, 2019 at 05:14:52PM -0700, Ralph Campbell wrote:
> HMM defines its own struct hmm_update which is passed to the
> sync_cpu_device_pagetables() callback function. This is
> sufficient when the only action is to invalidate. However,
> a device may want to know the reason for the invalidation and
> be able to see the new permissions on a range, update device access
> rights or range statistics. Since sync_cpu_device_pagetables()
> can be called from try_to_unmap(), the mmap_sem may not be held
> and find_vma() is not safe to be called.
> Pass the struct mmu_notifier_range to sync_cpu_device_pagetables()
> to allow the full invalidation information to be used.
>
> Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx>
I don't disagree with Christoph or Jason but since I've been trying to sort out
where hmm does and does not fit any chance to remove a custom structure is a
good simplification IMO. So...
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> ---
>
> I'm sending this out now since we are updating many of the HMM APIs
> and I think it will be useful.
>
>
> drivers/gpu/drm/nouveau/nouveau_svm.c | 4 ++--
> include/linux/hmm.h | 27 ++-------------------------
> mm/hmm.c | 13 ++++---------
> 3 files changed, 8 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
> index 8c92374afcf2..c34b98fafe2f 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -252,13 +252,13 @@ nouveau_svmm_invalidate(struct nouveau_svmm *svmm, u64 start, u64 limit)
>
> static int
> nouveau_svmm_sync_cpu_device_pagetables(struct hmm_mirror *mirror,
> - const struct hmm_update *update)
> + const struct mmu_notifier_range *update)
> {
> struct nouveau_svmm *svmm = container_of(mirror, typeof(*svmm), mirror);
> unsigned long start = update->start;
> unsigned long limit = update->end;
>
> - if (!update->blockable)
> + if (!mmu_notifier_range_blockable(update))
> return -EAGAIN;
>
> SVMM_DBG(svmm, "invalidate %016lx-%016lx", start, limit);
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index 0fa8ea34ccef..07a2d38fde34 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -377,29 +377,6 @@ static inline uint64_t hmm_pfn_from_pfn(const struct hmm_range *range,
>
> struct hmm_mirror;
>
> -/*
> - * enum hmm_update_event - type of update
> - * @HMM_UPDATE_INVALIDATE: invalidate range (no indication as to why)
> - */
> -enum hmm_update_event {
> - HMM_UPDATE_INVALIDATE,
> -};
> -
> -/*
> - * struct hmm_update - HMM update information for callback
> - *
> - * @start: virtual start address of the range to update
> - * @end: virtual end address of the range to update
> - * @event: event triggering the update (what is happening)
> - * @blockable: can the callback block/sleep ?
> - */
> -struct hmm_update {
> - unsigned long start;
> - unsigned long end;
> - enum hmm_update_event event;
> - bool blockable;
> -};
> -
> /*
> * struct hmm_mirror_ops - HMM mirror device operations callback
> *
> @@ -420,7 +397,7 @@ struct hmm_mirror_ops {
> /* sync_cpu_device_pagetables() - synchronize page tables
> *
> * @mirror: pointer to struct hmm_mirror
> - * @update: update information (see struct hmm_update)
> + * @update: update information (see struct mmu_notifier_range)
> * Return: -EAGAIN if update.blockable false and callback need to
> * block, 0 otherwise.
> *
> @@ -434,7 +411,7 @@ struct hmm_mirror_ops {
> * synchronous call.
> */
> int (*sync_cpu_device_pagetables)(struct hmm_mirror *mirror,
> - const struct hmm_update *update);
> + const struct mmu_notifier_range *update);
> };
>
> /*
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 9aad3550f2bb..b49a43712554 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -164,7 +164,6 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
> {
> struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
> struct hmm_mirror *mirror;
> - struct hmm_update update;
> struct hmm_range *range;
> unsigned long flags;
> int ret = 0;
> @@ -173,15 +172,10 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
> if (!kref_get_unless_zero(&hmm->kref))
> return 0;
>
> - update.start = nrange->start;
> - update.end = nrange->end;
> - update.event = HMM_UPDATE_INVALIDATE;
> - update.blockable = mmu_notifier_range_blockable(nrange);
> -
> spin_lock_irqsave(&hmm->ranges_lock, flags);
> hmm->notifiers++;
> list_for_each_entry(range, &hmm->ranges, list) {
> - if (update.end < range->start || update.start >= range->end)
> + if (nrange->end < range->start || nrange->start >= range->end)
> continue;
>
> range->valid = false;
> @@ -198,9 +192,10 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
> list_for_each_entry(mirror, &hmm->mirrors, list) {
> int rc;
>
> - rc = mirror->ops->sync_cpu_device_pagetables(mirror, &update);
> + rc = mirror->ops->sync_cpu_device_pagetables(mirror, nrange);
> if (rc) {
> - if (WARN_ON(update.blockable || rc != -EAGAIN))
> + if (WARN_ON(mmu_notifier_range_blockable(nrange) ||
> + rc != -EAGAIN))
> continue;
> ret = -EAGAIN;
> break;
> --
> 2.20.1
>
