drm/etnaviv: implement per-process address spaces on MMUv2

This builds on top of the MMU contexts introduced earlier. Instead of having
one context per GPU core, each GPU client receives its own context.

On MMUv1 this still means a single shared pagetable set is used by all
clients, but on MMUv2 there is now a distinct set of pagetables for each
client. As the command fetch is also translated via the MMU on MMUv2 the
kernel command ringbuffer is mapped into each of the client pagetables.

As the MMU context switch is a bit of a heavy operation, due to the needed
cache and TLB flushing, this patch implements a lazy way of switching the
MMU context. The kernel does not have its own MMU context, but reuses the
last client context for all of its operations. This has some visible impact,
as the GPU can now only be started once a client has submitted some work and
we got the client MMU context assigned. Also the MMU context has a different
lifetime than the general client context, as the GPU might still execute the
kernel command buffer in the context of a client even after the client has
completed all GPU work and has been terminated. Only when the GPU is runtime
suspended or switches to another clients MMU context is the old context
freed up.

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

drivers/gpu/drm/etnaviv/etnaviv_buffer.c

@@ -118,7 +118,8 @@ static void etnaviv_buffer_dump(struct etnaviv_gpu *gpu,
 	u32 *ptr = buf->vaddr + off;
 
 	dev_info(gpu->dev, "virt %p phys 0x%08x free 0x%08x\n",
-			ptr, etnaviv_cmdbuf_get_va(buf, &gpu->cmdbuf_mapping) +
+			ptr, etnaviv_cmdbuf_get_va(buf,
+			&gpu->mmu_context->cmdbuf_mapping) +
 			off, size - len * 4 - off);
 
 	print_hex_dump(KERN_INFO, "cmd ", DUMP_PREFIX_OFFSET, 16, 4,
@@ -152,7 +153,8 @@ static u32 etnaviv_buffer_reserve(struct etnaviv_gpu *gpu,
 	if (buffer->user_size + cmd_dwords * sizeof(u64) > buffer->size)
 		buffer->user_size = 0;
 
-	return etnaviv_cmdbuf_get_va(buffer, &gpu->cmdbuf_mapping) +
+	return etnaviv_cmdbuf_get_va(buffer,
+				     &gpu->mmu_context->cmdbuf_mapping) +
 	       buffer->user_size;
 }
 
@@ -166,7 +168,8 @@ u16 etnaviv_buffer_init(struct etnaviv_gpu *gpu)
 	buffer->user_size = 0;
 
 	CMD_WAIT(buffer);
-	CMD_LINK(buffer, 2, etnaviv_cmdbuf_get_va(buffer, &gpu->cmdbuf_mapping)
+	CMD_LINK(buffer, 2,
+		 etnaviv_cmdbuf_get_va(buffer, &gpu->mmu_context->cmdbuf_mapping)
 		 + buffer->user_size - 4);
 
 	return buffer->user_size / 8;
@@ -293,7 +296,8 @@ void etnaviv_sync_point_queue(struct etnaviv_gpu *gpu, unsigned int event)
 
 	/* Append waitlink */
 	CMD_WAIT(buffer);
-	CMD_LINK(buffer, 2, etnaviv_cmdbuf_get_va(buffer, &gpu->cmdbuf_mapping)
+	CMD_LINK(buffer, 2,
+		 etnaviv_cmdbuf_get_va(buffer, &gpu->mmu_context->cmdbuf_mapping)
 		 + buffer->user_size - 4);
 
 	/*
@@ -308,26 +312,29 @@ void etnaviv_sync_point_queue(struct etnaviv_gpu *gpu, unsigned int event)
 
 /* Append a command buffer to the ring buffer. */
 void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
-	unsigned int event, struct etnaviv_cmdbuf *cmdbuf)
+	struct etnaviv_iommu_context *mmu_context, unsigned int event,
+	struct etnaviv_cmdbuf *cmdbuf)
 {
 	struct etnaviv_cmdbuf *buffer = &gpu->buffer;
 	unsigned int waitlink_offset = buffer->user_size - 16;
 	u32 return_target, return_dwords;
 	u32 link_target, link_dwords;
 	bool switch_context = gpu->exec_state != exec_state;
+	bool switch_mmu_context = gpu->mmu_context != mmu_context;
 	unsigned int new_flush_seq = READ_ONCE(gpu->mmu_context->flush_seq);
-	bool need_flush = gpu->flush_seq != new_flush_seq;
+	bool need_flush = switch_mmu_context || gpu->flush_seq != new_flush_seq;
 
 	lockdep_assert_held(&gpu->lock);
 
 	if (drm_debug & DRM_UT_DRIVER)
 		etnaviv_buffer_dump(gpu, buffer, 0, 0x50);
 
-	link_target = etnaviv_cmdbuf_get_va(cmdbuf, &gpu->cmdbuf_mapping);
+	link_target = etnaviv_cmdbuf_get_va(cmdbuf,
+					    &gpu->mmu_context->cmdbuf_mapping);
 	link_dwords = cmdbuf->size / 8;
 
 	/*
-	 * If we need maintanence prior to submitting this buffer, we will
+	 * If we need maintenance prior to submitting this buffer, we will
 	 * need to append a mmu flush load state, followed by a new
 	 * link to this buffer - a total of four additional words.
 	 */
@@ -349,7 +356,24 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
 		if (switch_context)
 			extra_dwords += 4;
 
+		/* PTA load command */
+		if (switch_mmu_context && gpu->sec_mode == ETNA_SEC_KERNEL)
+			extra_dwords += 1;
+
 		target = etnaviv_buffer_reserve(gpu, buffer, extra_dwords);
+		/*
+		 * Switch MMU context if necessary. Must be done after the
+		 * link target has been calculated, as the jump forward in the
+		 * kernel ring still uses the last active MMU context before
+		 * the switch.
+		 */
+		if (switch_mmu_context) {
+			struct etnaviv_iommu_context *old_context = gpu->mmu_context;
+
+			etnaviv_iommu_context_get(mmu_context);
+			gpu->mmu_context = mmu_context;
+			etnaviv_iommu_context_put(old_context);
+		}
 
 		if (need_flush) {
 			/* Add the MMU flush */
@@ -361,10 +385,23 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
 					       VIVS_GL_FLUSH_MMU_FLUSH_PEMMU |
 					       VIVS_GL_FLUSH_MMU_FLUSH_UNK4);
 			} else {
+				u32 flush = VIVS_MMUv2_CONFIGURATION_MODE_MASK |
+					    VIVS_MMUv2_CONFIGURATION_FLUSH_FLUSH;
+
+				if (switch_mmu_context &&
+				    gpu->sec_mode == ETNA_SEC_KERNEL) {
+					unsigned short id =
+						etnaviv_iommuv2_get_pta_id(gpu->mmu_context);
+					CMD_LOAD_STATE(buffer,
+						VIVS_MMUv2_PTA_CONFIG,
+						VIVS_MMUv2_PTA_CONFIG_INDEX(id));
+				}
+
+				if (gpu->sec_mode == ETNA_SEC_NONE)
+					flush |= etnaviv_iommuv2_get_mtlb_addr(gpu->mmu_context);
+
 				CMD_LOAD_STATE(buffer, VIVS_MMUv2_CONFIGURATION,
-					VIVS_MMUv2_CONFIGURATION_MODE_MASK |
-					VIVS_MMUv2_CONFIGURATION_ADDRESS_MASK |
-					VIVS_MMUv2_CONFIGURATION_FLUSH_FLUSH);
+					       flush);
 				CMD_SEM(buffer, SYNC_RECIPIENT_FE,
 					SYNC_RECIPIENT_PE);
 				CMD_STALL(buffer, SYNC_RECIPIENT_FE,
@@ -380,6 +417,8 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
 		}
 
 		/* And the link to the submitted buffer */
+		link_target = etnaviv_cmdbuf_get_va(cmdbuf,
+					&gpu->mmu_context->cmdbuf_mapping);
 		CMD_LINK(buffer, link_dwords, link_target);
 
 		/* Update the link target to point to above instructions */
@@ -416,13 +455,14 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
 	CMD_LOAD_STATE(buffer, VIVS_GL_EVENT, VIVS_GL_EVENT_EVENT_ID(event) |
 		       VIVS_GL_EVENT_FROM_PE);
 	CMD_WAIT(buffer);
-	CMD_LINK(buffer, 2, etnaviv_cmdbuf_get_va(buffer, &gpu->cmdbuf_mapping)
+	CMD_LINK(buffer, 2,
+		 etnaviv_cmdbuf_get_va(buffer, &gpu->mmu_context->cmdbuf_mapping)
 		 + buffer->user_size - 4);
 
 	if (drm_debug & DRM_UT_DRIVER)
 		pr_info("stream link to 0x%08x @ 0x%08x %p\n",
 			return_target,
-			etnaviv_cmdbuf_get_va(cmdbuf, &gpu->cmdbuf_mapping),
+			etnaviv_cmdbuf_get_va(cmdbuf, &gpu->mmu_context->cmdbuf_mapping),
 			cmdbuf->vaddr);
 
 	if (drm_debug & DRM_UT_DRIVER) {

drivers/gpu/drm/etnaviv/etnaviv_drv.c

@@ -50,12 +50,19 @@ static int etnaviv_open(struct drm_device *dev, struct drm_file *file)
 {
 	struct etnaviv_drm_private *priv = dev->dev_private;
 	struct etnaviv_file_private *ctx;
-	int i;
+	int ret, i;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;
 
+	ctx->mmu = etnaviv_iommu_context_init(priv->mmu_global,
+					      priv->cmdbuf_suballoc);
+	if (!ctx->mmu) {
+		ret = -ENOMEM;
+		goto out_free;
+	}
+
 	for (i = 0; i < ETNA_MAX_PIPES; i++) {
 		struct etnaviv_gpu *gpu = priv->gpu[i];
 		struct drm_sched_rq *rq;
@@ -70,6 +77,10 @@ static int etnaviv_open(struct drm_device *dev, struct drm_file *file)
 	file->driver_priv = ctx;
 
 	return 0;
+
+out_free:
+	kfree(ctx);
+	return ret;
 }
 
 static void etnaviv_postclose(struct drm_device *dev, struct drm_file *file)
@@ -85,6 +96,8 @@ static void etnaviv_postclose(struct drm_device *dev, struct drm_file *file)
 			drm_sched_entity_destroy(&ctx->sched_entity[i]);
 	}
 
+	etnaviv_iommu_context_put(ctx->mmu);
+
 	kfree(ctx);
 }
 
@@ -116,12 +129,29 @@ static int etnaviv_mm_show(struct drm_device *dev, struct seq_file *m)
 static int etnaviv_mmu_show(struct etnaviv_gpu *gpu, struct seq_file *m)
 {
 	struct drm_printer p = drm_seq_file_printer(m);
+	struct etnaviv_iommu_context *mmu_context;
 
 	seq_printf(m, "Active Objects (%s):\n", dev_name(gpu->dev));
 
-	mutex_lock(&gpu->mmu_context->lock);
-	drm_mm_print(&gpu->mmu_context->mm, &p);
-	mutex_unlock(&gpu->mmu_context->lock);
+	/*
+	 * Lock the GPU to avoid a MMU context switch just now and elevate
+	 * the refcount of the current context to avoid it disappearing from
+	 * under our feet.
+	 */
+	mutex_lock(&gpu->lock);
+	mmu_context = gpu->mmu_context;
+	if (mmu_context)
+		etnaviv_iommu_context_get(mmu_context);
+	mutex_unlock(&gpu->lock);
+
+	if (!mmu_context)
+		return 0;
+
+	mutex_lock(&mmu_context->lock);
+	drm_mm_print(&mmu_context->mm, &p);
+	mutex_unlock(&mmu_context->lock);
+
+	etnaviv_iommu_context_put(mmu_context);
 
 	return 0;
 }

drivers/gpu/drm/etnaviv/etnaviv_drv.h

@@ -25,10 +25,7 @@ struct etnaviv_gem_submit;
 struct etnaviv_iommu_global;
 
 struct etnaviv_file_private {
-	/*
-	 * When per-context address spaces are supported we'd keep track of
-	 * the context's page-tables here.
-	 */
+	struct etnaviv_iommu_context	*mmu;
 	struct drm_sched_entity		sched_entity[ETNA_MAX_PIPES];
 };
 
@@ -75,6 +72,7 @@ u16 etnaviv_buffer_config_pta(struct etnaviv_gpu *gpu, unsigned short id);
 void etnaviv_buffer_end(struct etnaviv_gpu *gpu);
 void etnaviv_sync_point_queue(struct etnaviv_gpu *gpu, unsigned int event);
 void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
+	struct etnaviv_iommu_context *mmu,
 	unsigned int event, struct etnaviv_cmdbuf *cmdbuf);
 void etnaviv_validate_init(void);
 bool etnaviv_cmd_validate_one(struct etnaviv_gpu *gpu,

drivers/gpu/drm/etnaviv/etnaviv_dump.c

@@ -173,12 +173,12 @@ void etnaviv_core_dump(struct etnaviv_gem_submit *submit)
 	etnaviv_core_dump_mem(&iter, ETDUMP_BUF_RING, gpu->buffer.vaddr,
 			      gpu->buffer.size,
 			      etnaviv_cmdbuf_get_va(&gpu->buffer,
-						    &gpu->cmdbuf_mapping));
+					&gpu->mmu_context->cmdbuf_mapping));
 
 	etnaviv_core_dump_mem(&iter, ETDUMP_BUF_CMD,
 			      submit->cmdbuf.vaddr, submit->cmdbuf.size,
 			      etnaviv_cmdbuf_get_va(&submit->cmdbuf,
-						    &gpu->cmdbuf_mapping));
+					&gpu->mmu_context->cmdbuf_mapping));
 
 	/* Reserve space for the bomap */
 	if (n_bomap_pages) {

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -248,8 +248,7 @@ 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_gpu *gpu,
-	struct etnaviv_iommu_context *mmu_context)
+	struct drm_gem_object *obj, struct etnaviv_iommu_context *mmu_context)
 {
 	struct etnaviv_gem_object *etnaviv_obj = to_etnaviv_bo(obj);
 	struct etnaviv_vram_mapping *mapping;
@@ -308,8 +307,8 @@ struct etnaviv_vram_mapping *etnaviv_gem_mapping_get(
 	mapping->context = mmu_context;
 	mapping->use = 1;
 
-	ret = etnaviv_iommu_map_gem(mmu_context, etnaviv_obj, gpu->memory_base,
-				    mapping);
+	ret = etnaviv_iommu_map_gem(mmu_context, etnaviv_obj,
+				    mmu_context->global->memory_base, mapping);
 	if (ret < 0) {
 		etnaviv_iommu_context_put(mmu_context);
 		kfree(mapping);

drivers/gpu/drm/etnaviv/etnaviv_gem.h

@@ -93,6 +93,7 @@ struct etnaviv_gem_submit {
 	struct kref refcount;
 	struct etnaviv_file_private *ctx;
 	struct etnaviv_gpu *gpu;
+	struct etnaviv_iommu_context *mmu_context, *prev_mmu_context;
 	struct dma_fence *out_fence, *in_fence;
 	int out_fence_id;
 	struct list_head node; /* GPU active submit list */
@@ -119,8 +120,7 @@ struct page **etnaviv_gem_get_pages(struct etnaviv_gem_object *obj);
 void etnaviv_gem_put_pages(struct etnaviv_gem_object *obj);
 
 struct etnaviv_vram_mapping *etnaviv_gem_mapping_get(
-	struct drm_gem_object *obj, struct etnaviv_gpu *gpu,
-	struct etnaviv_iommu_context *mmu_context);
+	struct drm_gem_object *obj, struct etnaviv_iommu_context *mmu_context);
 void etnaviv_gem_mapping_unreference(struct etnaviv_vram_mapping *mapping);
 
 #endif /* __ETNAVIV_GEM_H__ */

drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c

@@ -224,8 +224,7 @@ static int submit_pin_objects(struct etnaviv_gem_submit *submit)
 		struct etnaviv_vram_mapping *mapping;
 
 		mapping = etnaviv_gem_mapping_get(&etnaviv_obj->base,
-						  submit->gpu,
-						  submit->gpu->mmu_context);
+						  submit->mmu_context);
 		if (IS_ERR(mapping)) {
 			ret = PTR_ERR(mapping);
 			break;
@@ -362,6 +361,12 @@ static void submit_cleanup(struct kref *kref)
 	if (submit->cmdbuf.suballoc)
 		etnaviv_cmdbuf_free(&submit->cmdbuf);
 
+	if (submit->mmu_context)
+		etnaviv_iommu_context_put(submit->mmu_context);
+
+	if (submit->prev_mmu_context)
+		etnaviv_iommu_context_put(submit->prev_mmu_context);
+
 	for (i = 0; i < submit->nr_bos; i++) {
 		struct etnaviv_gem_object *etnaviv_obj = submit->bos[i].obj;
 
@@ -503,6 +508,8 @@ int etnaviv_ioctl_gem_submit(struct drm_device *dev, void *data,
 		goto err_submit_objects;
 
 	submit->ctx = file->driver_priv;
+	etnaviv_iommu_context_get(submit->ctx->mmu);
+	submit->mmu_context = submit->ctx->mmu;
 	submit->exec_state = args->exec_state;
 	submit->flags = args->flags;