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>

1 files changed, 32 insertions, 10 deletions

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
index 2f64eef773ed..82822e30bf30 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
@@ -290,6 +290,8 @@ static void etnaviv_iommu_context_free(struct kref *kref)
 	struct etnaviv_iommu_context *context =
 		container_of(kref, struct etnaviv_iommu_context, refcount);
 
+	etnaviv_cmdbuf_suballoc_unmap(context, &context->cmdbuf_mapping);
+
 	context->global->ops->free(context);
 }
 void etnaviv_iommu_context_put(struct etnaviv_iommu_context *context)
@@ -298,12 +300,28 @@ void etnaviv_iommu_context_put(struct etnaviv_iommu_context *context)
 }
 
 struct etnaviv_iommu_context *
-etnaviv_iommu_context_init(struct etnaviv_iommu_global *global)
+etnaviv_iommu_context_init(struct etnaviv_iommu_global *global,
+			   struct etnaviv_cmdbuf_suballoc *suballoc)
 {
+	struct etnaviv_iommu_context *ctx;
+	int ret;
+
 	if (global->version == ETNAVIV_IOMMU_V1)
-		return etnaviv_iommuv1_context_alloc(global);
+		ctx = etnaviv_iommuv1_context_alloc(global);
 	else
-		return etnaviv_iommuv2_context_alloc(global);
+		ctx = etnaviv_iommuv2_context_alloc(global);
+
+	if (!ctx)
+		return NULL;
+
+	ret = etnaviv_cmdbuf_suballoc_map(suballoc, ctx, &ctx->cmdbuf_mapping,
+					  global->memory_base);
+	if (ret) {
+		global->ops->free(ctx);
+		return NULL;
+	}
+
+	return ctx;
 }
 
 void etnaviv_iommu_restore(struct etnaviv_gpu *gpu,
@@ -319,6 +337,12 @@ int etnaviv_iommu_get_suballoc_va(struct etnaviv_iommu_context *context,
 {
 	mutex_lock(&context->lock);
 
+	if (mapping->use > 0) {
+		mapping->use++;
+		mutex_unlock(&context->lock);
+		return 0;
+	}
+
 	/*
 	 * For MMUv1 we don't add the suballoc region to the pagetables, as
 	 * those GPUs can only work with cmdbufs accessed through the linear
@@ -340,7 +364,6 @@ int etnaviv_iommu_get_suballoc_va(struct etnaviv_iommu_context *context,
 		mapping->iova = node->start;
 		ret = etnaviv_context_map(context, node->start, paddr, size,
 					  ETNAVIV_PROT_READ);
-
 		if (ret < 0) {
 			drm_mm_remove_node(node);
 			mutex_unlock(&context->lock);
@@ -363,15 +386,14 @@ void etnaviv_iommu_put_suballoc_va(struct etnaviv_iommu_context *context,
 {
 	struct drm_mm_node *node = &mapping->vram_node;
 
-	if (!mapping->use)
-		return;
-
-	mapping->use = 0;
+	mutex_lock(&context->lock);
+	mapping->use--;
 
-	if (context->global->version == ETNAVIV_IOMMU_V1)
+	if (mapping->use > 0 || context->global->version == ETNAVIV_IOMMU_V1) {
+		mutex_unlock(&context->lock);
 		return;
+	}
 
-	mutex_lock(&context->lock);
 	etnaviv_context_unmap(context, node->start, node->size);
 	drm_mm_remove_node(node);
 	mutex_unlock(&context->lock);