drm/etnaviv: implement softpin

With softpin we allow the userspace to take control over the GPU virtual
address space. The new capability is relected by a bump of the minor DRM
version. There are a few restrictions for userspace to take into
account:

1. The kernel reserves a bit of the address space to implement zero page
faulting and mapping of the kernel internal ring buffer. Userspace can
query the kernel for the first usable GPU VM address via
ETNAVIV_PARAM_SOFTPIN_START_ADDR.

2. We only allow softpin on GPUs, which implement proper process
separation via PPAS. If softpin is not available the softpin start
address will be set to ~0.

3. Softpin is all or nothing. A submit using softpin must not use any
address fixups via relocs.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Guido Günther <agx@sigxcpu.org>

7 files changed, 42 insertions, 4 deletions

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_cmdbuf.c b/drivers/gpu/drm/etnaviv/etnaviv_cmdbuf.c
index f39430ba3593..9dc20d892c15 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_cmdbuf.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_cmdbuf.c
@@ -44,6 +44,7 @@ etnaviv_cmdbuf_suballoc_new(struct device *dev)
 	mutex_init(&suballoc->lock);
 	init_waitqueue_head(&suballoc->free_event);
 
+	BUILD_BUG_ON(ETNAVIV_SOFTPIN_START_ADDRESS < SUBALLOC_SIZE);
 	suballoc->vaddr = dma_alloc_wc(dev, SUBALLOC_SIZE,
 				       &suballoc->paddr, GFP_KERNEL);
 	if (!suballoc->vaddr) {
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
index 80f1edcbbea0..45851d510f62 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
@@ -529,7 +529,7 @@ static struct drm_driver etnaviv_drm_driver = {
 	.desc               = "etnaviv DRM",
 	.date               = "20151214",
 	.major              = 1,
-	.minor              = 2,
+	.minor              = 3,
 };
 
 /*
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
index a488cfdb6bbf..32cfa5a48d42 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
@@ -24,6 +24,8 @@ struct etnaviv_gem_object;
 struct etnaviv_gem_submit;
 struct etnaviv_iommu_global;
 
+#define ETNAVIV_SOFTPIN_START_ADDRESS	SZ_4M /* must be >= SUBALLOC_SIZE */
+
 struct etnaviv_file_private {
 	struct etnaviv_iommu_context	*mmu;
 	struct drm_sched_entity		sched_entity[ETNA_MAX_PIPES];
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index 8c62c5e0a494..401ce4512b8d 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -248,7 +248,8 @@ void etnaviv_gem_mapping_unreference(struct etnaviv_vram_mapping *mapping)
 }
 
 struct etnaviv_vram_mapping *etnaviv_gem_mapping_get(
-	struct drm_gem_object *obj, struct etnaviv_iommu_context *mmu_context)
+	struct drm_gem_object *obj, struct etnaviv_iommu_context *mmu_context,
+	u64 va)
 {
 	struct etnaviv_gem_object *etnaviv_obj = to_etnaviv_bo(obj);
 	struct etnaviv_vram_mapping *mapping;
@@ -309,7 +310,7 @@ struct etnaviv_vram_mapping *etnaviv_gem_mapping_get(
 
 	ret = etnaviv_iommu_map_gem(mmu_context, etnaviv_obj,
 				    mmu_context->global->memory_base,
-				    mapping, 0);
+				    mapping, va);
 	if (ret < 0) {
 		etnaviv_iommu_context_put(mmu_context);
 		kfree(mapping);
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.h b/drivers/gpu/drm/etnaviv/etnaviv_gem.h
index 2d01ee1f65c1..f1164934ecdf 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.h
@@ -77,6 +77,7 @@ static inline bool is_active(struct etnaviv_gem_object *etnaviv_obj)
 
 struct etnaviv_gem_submit_bo {
 	u32 flags;
+	u64 va;
 	struct etnaviv_gem_object *obj;
 	struct etnaviv_vram_mapping *mapping;
 	struct dma_fence *excl;
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
index 63a1206492d2..75afce42921b 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
@@ -72,6 +72,14 @@ static int submit_lookup_objects(struct etnaviv_gem_submit *submit,
 		}
 
 		submit->bos[i].flags = bo->flags;
+		if (submit->flags & ETNA_SUBMIT_SOFTPIN) {
+			if (bo->presumed < ETNAVIV_SOFTPIN_START_ADDRESS) {
+				DRM_ERROR("invalid softpin address\n");
+				ret = -EINVAL;
+				goto out_unlock;
+			}
+			submit->bos[i].va = bo->presumed;
+		}
 
 		/* normally use drm_gem_object_lookup(), but for bulk lookup
 		 * all under single table_lock just hit object_idr directly:
@@ -224,11 +232,17 @@ static int submit_pin_objects(struct etnaviv_gem_submit *submit)
 		struct etnaviv_vram_mapping *mapping;
 
 		mapping = etnaviv_gem_mapping_get(&etnaviv_obj->base,
-						  submit->mmu_context);
+						  submit->mmu_context,
+						  submit->bos[i].va);
 		if (IS_ERR(mapping)) {
 			ret = PTR_ERR(mapping);
 			break;
 		}
+
+		if ((submit->flags & ETNA_SUBMIT_SOFTPIN) &&
+		     submit->bos[i].va != mapping->iova)
+			return -EINVAL;
+
 		atomic_inc(&etnaviv_obj->gpu_active);
 
 		submit->bos[i].flags |= BO_PINNED;
@@ -261,6 +275,10 @@ static int submit_reloc(struct etnaviv_gem_submit *submit, void *stream,
 	u32 *ptr = stream;
 	int ret;
 
+	/* Submits using softpin don't blend with relocs */
+	if ((submit->flags & ETNA_SUBMIT_SOFTPIN) && nr_relocs != 0)
+		return -EINVAL;
+
 	for (i = 0; i < nr_relocs; i++) {
 		const struct drm_etnaviv_gem_submit_reloc *r = relocs + i;
 		struct etnaviv_gem_submit_bo *bo;
@@ -445,6 +463,12 @@ int etnaviv_ioctl_gem_submit(struct drm_device *dev, void *data,
 		return -EINVAL;
 	}
 
+	if ((args->flags & ETNA_SUBMIT_SOFTPIN) &&
+	    priv->mmu_global->version != ETNAVIV_IOMMU_V2) {
+		DRM_ERROR("softpin requested on incompatible MMU\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * Copy the command submission and bo array to kernel space in
 	 * one go, and do this outside of any locks.
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
index d8a83ebfce47..d47d1a8e0219 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
@@ -42,6 +42,8 @@ static const struct platform_device_id gpu_ids[] = {
 
 int etnaviv_gpu_get_param(struct etnaviv_gpu *gpu, u32 param, u64 *value)
 {
+	struct etnaviv_drm_private *priv = gpu->drm->dev_private;
+
 	switch (param) {
 	case ETNAVIV_PARAM_GPU_MODEL:
 		*value = gpu->identity.model;
@@ -147,6 +149,13 @@ int etnaviv_gpu_get_param(struct etnaviv_gpu *gpu, u32 param, u64 *value)
 		*value = gpu->identity.varyings_count;
 		break;
 
+	case ETNAVIV_PARAM_SOFTPIN_START_ADDR:
+		if (priv->mmu_global->version == ETNAVIV_IOMMU_V2)
+			*value = ETNAVIV_SOFTPIN_START_ADDRESS;
+		else
+			*value = ~0ULL;
+		break;
+
 	default:
 		DBG("%s: invalid param: %u", dev_name(gpu->dev), param);
 		return -EINVAL;