Commit b14b8c5f authored by Rob Clark's avatar Rob Clark

drm/msm: Decouple vma tracking from obj lock

We need to use the inuse count to track that a BO is pinned until
we have the hw_fence.  But we want to remove the obj lock from the
job_run() path as this could deadlock against reclaim/shrinker
(because it is blocking the hw_fence from eventually being signaled).
So split that tracking out into a per-vma lock with narrower scope.
Signed-off-by: default avatarRob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/527839/
Link: https://lore.kernel.org/r/20230320144356.803762-5-robdclark@gmail.com
parent fc2f0756
......@@ -59,6 +59,7 @@ struct msm_fence_context;
struct msm_gem_vma {
struct drm_mm_node node;
spinlock_t lock;
uint64_t iova;
struct msm_gem_address_space *aspace;
struct list_head list; /* node in msm_gem_object::vmas */
......
......@@ -40,19 +40,28 @@ msm_gem_address_space_get(struct msm_gem_address_space *aspace)
bool msm_gem_vma_inuse(struct msm_gem_vma *vma)
{
bool ret = true;
spin_lock(&vma->lock);
if (vma->inuse > 0)
return true;
goto out;
while (vma->fence_mask) {
unsigned idx = ffs(vma->fence_mask) - 1;
if (!msm_fence_completed(vma->fctx[idx], vma->fence[idx]))
return true;
goto out;
vma->fence_mask &= ~BIT(idx);
}
return false;
ret = false;
out:
spin_unlock(&vma->lock);
return ret;
}
/* Actually unmap memory for the vma */
......@@ -73,8 +82,7 @@ void msm_gem_vma_purge(struct msm_gem_vma *vma)
vma->mapped = false;
}
/* Remove reference counts for the mapping */
void msm_gem_vma_unpin(struct msm_gem_vma *vma)
static void vma_unpin_locked(struct msm_gem_vma *vma)
{
if (GEM_WARN_ON(!vma->inuse))
return;
......@@ -82,13 +90,23 @@ void msm_gem_vma_unpin(struct msm_gem_vma *vma)
vma->inuse--;
}
/* Remove reference counts for the mapping */
void msm_gem_vma_unpin(struct msm_gem_vma *vma)
{
spin_lock(&vma->lock);
vma_unpin_locked(vma);
spin_unlock(&vma->lock);
}
/* Replace pin reference with fence: */
void msm_gem_vma_unpin_fenced(struct msm_gem_vma *vma, struct msm_fence_context *fctx)
{
spin_lock(&vma->lock);
vma->fctx[fctx->index] = fctx;
vma->fence[fctx->index] = fctx->last_fence;
vma->fence_mask |= BIT(fctx->index);
msm_gem_vma_unpin(vma);
vma_unpin_locked(vma);
spin_unlock(&vma->lock);
}
/* Map and pin vma: */
......@@ -103,7 +121,9 @@ msm_gem_vma_map(struct msm_gem_vma *vma, int prot,
return -EINVAL;
/* Increase the usage counter */
spin_lock(&vma->lock);
vma->inuse++;
spin_unlock(&vma->lock);
if (vma->mapped)
return 0;
......@@ -113,11 +133,22 @@ msm_gem_vma_map(struct msm_gem_vma *vma, int prot,
if (!aspace)
return 0;
/*
* NOTE: iommu/io-pgtable can allocate pages, so we cannot hold
* a lock across map/unmap which is also used in the job_run()
* path, as this can cause deadlock in job_run() vs shrinker/
* reclaim.
*
* Revisit this if we can come up with a scheme to pre-alloc pages
* for the pgtable in map/unmap ops.
*/
ret = aspace->mmu->funcs->map(aspace->mmu, vma->iova, sgt, size, prot);
if (ret) {
vma->mapped = false;
spin_lock(&vma->lock);
vma->inuse--;
spin_unlock(&vma->lock);
}
return ret;
......@@ -148,6 +179,7 @@ struct msm_gem_vma *msm_gem_vma_new(struct msm_gem_address_space *aspace)
if (!vma)
return NULL;
spin_lock_init(&vma->lock);
vma->aspace = aspace;
return vma;
......
......@@ -23,8 +23,8 @@ static struct dma_fence *msm_job_run(struct drm_sched_job *job)
for (i = 0; i < submit->nr_bos; i++) {
struct drm_gem_object *obj = &submit->bos[i].obj->base;
msm_gem_lock(obj);
msm_gem_vma_unpin_fenced(submit->bos[i].vma, fctx);
msm_gem_lock(obj);
msm_gem_unpin_locked(obj);
msm_gem_unlock(obj);
submit->bos[i].flags &= ~(BO_VMA_PINNED | BO_OBJ_PINNED);
......
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