Commit 1ed3d256 authored by Christian König's avatar Christian König Committed by Alex Deucher
Browse files

drm/amdgpu: keep the MMU lock until the update ends v4 



This is quite controversial because it adds another lock which is held during
page table updates, but I don't see much other option.

v2: allow multiple updates to be in flight at the same time
v3: simplify the patch, take the read side only once
v4: correctly fix rebase conflict

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarFelix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent aebc5e6f

drivers/gpu/drm/amd/amdgpu/amdgpu.h

+2 −2
Original line number Diff line number Diff line
@@ -1204,11 +1204,11 @@ void amdgpu_test_moves(struct amdgpu_device *adev); 
 * MMU Notifier

 */

#if defined(CONFIG_MMU_NOTIFIER)

void amdgpu_mn_lock(struct amdgpu_mn *mn);

void amdgpu_mn_unlock(struct amdgpu_mn *mn);

struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev);

int amdgpu_mn_register(struct amdgpu_bo *bo, unsigned long addr);

void amdgpu_mn_unregister(struct amdgpu_bo *bo);

void amdgpu_mn_lock(struct amdgpu_mn *mn);

void amdgpu_mn_unlock(struct amdgpu_mn *mn);

#else

static inline void amdgpu_mn_lock(struct amdgpu_mn *mn) {}

static inline void amdgpu_mn_unlock(struct amdgpu_mn *mn) {}

drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c

+55 −4
Original line number Diff line number Diff line
@@ -52,6 +52,8 @@ struct amdgpu_mn { 
	/* objects protected by lock */

	struct rw_semaphore	lock;

	struct rb_root		objects;

	struct mutex		read_lock;

	atomic_t		recursion;

};



struct amdgpu_mn_node {
@@ -125,6 +127,34 @@ void amdgpu_mn_unlock(struct amdgpu_mn *mn) 
		up_write(&mn->lock);

}



/**

 * amdgpu_mn_read_lock - take the rmn read lock

 *

 * @rmn: our notifier

 *

 * Take the rmn read side lock.

 */

static void amdgpu_mn_read_lock(struct amdgpu_mn *rmn)

{

	mutex_lock(&rmn->read_lock);

	if (atomic_inc_return(&rmn->recursion) == 1)

		down_read_non_owner(&rmn->lock);

	mutex_unlock(&rmn->read_lock);

}



/**

 * amdgpu_mn_read_unlock - drop the rmn read lock

 *

 * @rmn: our notifier

 *

 * Drop the rmn read side lock.

 */

static void amdgpu_mn_read_unlock(struct amdgpu_mn *rmn)

{

	if (atomic_dec_return(&rmn->recursion) == 0)

		up_read_non_owner(&rmn->lock);

}



/**

 * amdgpu_mn_invalidate_node - unmap all BOs of a node

 *
@@ -171,7 +201,7 @@ static void amdgpu_mn_invalidate_page(struct mmu_notifier *mn, 
	struct amdgpu_mn *rmn = container_of(mn, struct amdgpu_mn, mn);

	struct interval_tree_node *it;



	down_read(&rmn->lock);

	amdgpu_mn_read_lock(rmn);



	it = interval_tree_iter_first(&rmn->objects, address, address);

	if (it) {
@@ -181,7 +211,7 @@ static void amdgpu_mn_invalidate_page(struct mmu_notifier *mn, 
		amdgpu_mn_invalidate_node(node, address, address);

	}



	up_read(&rmn->lock);

	amdgpu_mn_read_unlock(rmn);

}



/**
@@ -206,7 +236,7 @@ static void amdgpu_mn_invalidate_range_start(struct mmu_notifier *mn, 
	/* notification is exclusive, but interval is inclusive */

	end -= 1;



	down_read(&rmn->lock);

	amdgpu_mn_read_lock(rmn);



	it = interval_tree_iter_first(&rmn->objects, start, end);

	while (it) {
@@ -217,14 +247,33 @@ static void amdgpu_mn_invalidate_range_start(struct mmu_notifier *mn, 


		amdgpu_mn_invalidate_node(node, start, end);

	}

}



/**

 * amdgpu_mn_invalidate_range_end - callback to notify about mm change

 *

 * @mn: our notifier

 * @mn: the mm this callback is about

 * @start: start of updated range

 * @end: end of updated range

 *

 * Release the lock again to allow new command submissions.

 */

static void amdgpu_mn_invalidate_range_end(struct mmu_notifier *mn,

					   struct mm_struct *mm,

					   unsigned long start,

					   unsigned long end)

{

	struct amdgpu_mn *rmn = container_of(mn, struct amdgpu_mn, mn);



	up_read(&rmn->lock);

	amdgpu_mn_read_unlock(rmn);

}



static const struct mmu_notifier_ops amdgpu_mn_ops = {

	.release = amdgpu_mn_release,

	.invalidate_page = amdgpu_mn_invalidate_page,

	.invalidate_range_start = amdgpu_mn_invalidate_range_start,

	.invalidate_range_end = amdgpu_mn_invalidate_range_end,

};



/**
@@ -261,6 +310,8 @@ struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev) 
	rmn->mn.ops = &amdgpu_mn_ops;

	init_rwsem(&rmn->lock);

	rmn->objects = RB_ROOT;

	mutex_init(&rmn->read_lock);

	atomic_set(&rmn->recursion, 0);



	r = __mmu_notifier_register(&rmn->mn, mm);

	if (r)

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