[RFC 13/24] drm/msm: Lazily create context VM

[Rob Clark <robdclark@gmail.com>]

From: Rob Clark <robdclark@chromium.org>

In the next commit, a way for userspace to opt-in to userspace managed
VM is added.  For this to work, we need to defer creation of the VM
until it is needed.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c   |  3 ++-
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 13 ++++++-----
 drivers/gpu/drm/msm/msm_drv.c           | 29 ++++++++++++++++++++-----
 drivers/gpu/drm/msm/msm_gem_submit.c    |  2 +-
 drivers/gpu/drm/msm/msm_gpu.h           |  9 +++++++-
 5 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 79a692288d18..97ec1dedeb98 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -112,6 +112,7 @@ static void a6xx_set_pagetable(struct a6xx_gpu *a6xx_gpu,
 {
 	bool sysprof = refcount_read(&a6xx_gpu->base.base.sysprof_active) > 1;
 	struct msm_context *ctx = submit->queue->ctx;
+	struct drm_gpuvm *vm = msm_context_vm(submit->dev, ctx);
 	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
 	phys_addr_t ttbr;
 	u32 asid;
@@ -120,7 +121,7 @@ static void a6xx_set_pagetable(struct a6xx_gpu *a6xx_gpu,
 	if (ctx->seqno == ring->cur_ctx_seqno)
 		return;
 
-	if (msm_iommu_pagetable_params(to_msm_vm(ctx->vm)->mmu, &ttbr, &asid))
+	if (msm_iommu_pagetable_params(to_msm_vm(vm)->mmu, &ttbr, &asid))
 		return;
 
 	if (adreno_gpu->info->family >= ADRENO_7XX_GEN1) {
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index 3104ad878cf1..033c1c9c457e 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -313,6 +313,7 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_context *ctx,
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	struct drm_device *drm = gpu->dev;
+	struct drm_gpuvm *vm = msm_context_vm(drm, ctx);
 
 	/* No pointer params yet */
 	if (*len != 0)
@@ -358,8 +359,8 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_context *ctx,
 		*value = 0;
 		return 0;
 	case MSM_PARAM_FAULTS:
-		if (ctx->vm)
-			*value = gpu->global_faults + to_msm_vm(ctx->vm)->faults;
+		if (vm)
+			*value = gpu->global_faults + to_msm_vm(vm)->faults;
 		else
 			*value = gpu->global_faults;
 		return 0;
@@ -367,14 +368,14 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_context *ctx,
 		*value = gpu->suspend_count;
 		return 0;
 	case MSM_PARAM_VA_START:
-		if (ctx->vm == gpu->vm)
+		if (vm == gpu->vm)
 			return UERR(EINVAL, drm, "requires per-process pgtables");
-		*value = ctx->vm->mm_start;
+		*value = vm->mm_start;
 		return 0;
 	case MSM_PARAM_VA_SIZE:
-		if (ctx->vm == gpu->vm)
+		if (vm == gpu->vm)
 			return UERR(EINVAL, drm, "requires per-process pgtables");
-		*value = ctx->vm->mm_range;
+		*value = vm->mm_range;
 		return 0;
 	case MSM_PARAM_HIGHEST_BANK_BIT:
 		*value = adreno_gpu->ubwc_config.highest_bank_bit;
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index ab0998c2e846..7a23549db97d 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -214,10 +214,29 @@ static void load_gpu(struct drm_device *dev)
 	mutex_unlock(&init_lock);
 }
 
+/**
+ * msm_context_vm - lazily create the context's VM
+ *
+ * @dev: the drm device
+ * @ctx: the context
+ *
+ * The VM is lazily created, so that userspace has a chance to opt-in to having
+ * a userspace managed VM before the VM is created.
+ *
+ * Note that this does not return a reference to the VM.  Once the VM is created,
+ * it exists for the lifetime of the context.
+ */
+struct drm_gpuvm *msm_context_vm(struct drm_device *dev, struct msm_context *ctx)
+{
+	struct msm_drm_private *priv = dev->dev_private;
+	if (!ctx->vm)
+		ctx->vm = msm_gpu_create_private_vm(priv->gpu, current);
+	return ctx->vm;
+}
+
 static int context_init(struct drm_device *dev, struct drm_file *file)
 {
 	static atomic_t ident = ATOMIC_INIT(0);
-	struct msm_drm_private *priv = dev->dev_private;
 	struct msm_context *ctx;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
@@ -230,7 +249,6 @@ static int context_init(struct drm_device *dev, struct drm_file *file)
 	kref_init(&ctx->ref);
 	msm_submitqueue_init(dev, ctx);
 
-	ctx->vm = msm_gpu_create_private_vm(priv->gpu, current);
 	file->driver_priv = ctx;
 
 	ctx->seqno = atomic_inc_return(&ident);
@@ -408,7 +426,7 @@ static int msm_ioctl_gem_info_iova(struct drm_device *dev,
 	 * Don't pin the memory here - just get an address so that userspace can
 	 * be productive
 	 */
-	return msm_gem_get_iova(obj, ctx->vm, iova);
+	return msm_gem_get_iova(obj, msm_context_vm(dev, ctx), iova);
 }
 
 static int msm_ioctl_gem_info_set_iova(struct drm_device *dev,
@@ -417,18 +435,19 @@ static int msm_ioctl_gem_info_set_iova(struct drm_device *dev,
 {
 	struct msm_drm_private *priv = dev->dev_private;
 	struct msm_context *ctx = file->driver_priv;
+	struct drm_gpuvm *vm = msm_context_vm(dev, ctx);
 
 	if (!priv->gpu)
 		return -EINVAL;
 
 	/* Only supported if per-process address space is supported: */
-	if (priv->gpu->vm == ctx->vm)
+	if (priv->gpu->vm == vm)
 		return UERR(EOPNOTSUPP, dev, "requires per-process pgtables");
 
 	if (should_fail(&fail_gem_iova, obj->size))
 		return -ENOMEM;
 
-	return msm_gem_set_iova(obj, ctx->vm, iova);
+	return msm_gem_set_iova(obj, vm, iova);
 }
 
 static int msm_ioctl_gem_info_set_metadata(struct drm_gem_object *obj,
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index 51c92fe1146f..5e37e1dad5bb 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -63,7 +63,7 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev,
 
 	kref_init(&submit->ref);
 	submit->dev = dev;
-	submit->vm = queue->ctx->vm;
+	submit->vm = msm_context_vm(dev, queue->ctx);
 	submit->gpu = gpu;
 	submit->cmd = (void *)&submit->bos[nr_bos];
 	submit->queue = queue;
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index ad6f14891205..5efbca0b9fb1 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -354,7 +354,12 @@ struct msm_context {
 	 */
 	int queueid;
 
-	/** @vm: the per-process GPU address-space */
+	/**
+	 * @vm:
+	 *
+	 * The per-process GPU address-space.  Do not access directly, use
+	 * msm_context_vm().
+	 */
 	struct drm_gpuvm *vm;
 
 	/** @kref: the reference count */
@@ -439,6 +444,8 @@ struct msm_context {
 	atomic64_t ctx_mem;
 };
 
+struct drm_gpuvm *msm_context_vm(struct drm_device *dev, struct msm_context *ctx);
+
 /**
  * msm_gpu_convert_priority - Map userspace priority to ring # and sched priority
  *
-- 
2.47.1