drm/nouveau: retain device pointer in nvkm_gsp_mem object

Store the struct device pointer used to allocate the DMA buffer in
the nvkm_gsp_mem object.  This allows nvkm_gsp_mem_dtor() to release
the buffer without needing the nvkm_gsp.  This is needed so that
we can retain DMA buffers even after the nvkm_gsp object is deleted.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241030202952.694055-1-ttabi@nvidia.com

Author: ttabi

drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h

@@ -9,6 +9,7 @@
 #define GSP_PAGE_SIZE  BIT(GSP_PAGE_SHIFT)
 
 struct nvkm_gsp_mem {
+	struct device *dev;
 	size_t size;
 	void *data;
 	dma_addr_t addr;

drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c

@@ -1000,7 +1000,7 @@ r535_gsp_rpc_get_gsp_static_info(struct nvkm_gsp *gsp)
 }
 
 static void
-nvkm_gsp_mem_dtor(struct nvkm_gsp *gsp, struct nvkm_gsp_mem *mem)
+nvkm_gsp_mem_dtor(struct nvkm_gsp_mem *mem)
 {
 	if (mem->data) {
 		/*
@@ -1009,19 +1009,35 @@ nvkm_gsp_mem_dtor(struct nvkm_gsp *gsp, struct nvkm_gsp_mem *mem)
 		 */
 		memset(mem->data, 0xFF, mem->size);
 
-		dma_free_coherent(gsp->subdev.device->dev, mem->size, mem->data, mem->addr);
+		dma_free_coherent(mem->dev, mem->size, mem->data, mem->addr);
+		put_device(mem->dev);
+
 		memset(mem, 0, sizeof(*mem));
 	}
 }
 
+/**
+ * nvkm_gsp_mem_ctor - constructor for nvkm_gsp_mem objects
+ * @gsp: gsp pointer
+ * @size: number of bytes to allocate
+ * @mem: nvkm_gsp_mem object to initialize
+ *
+ * Allocates a block of memory for use with GSP.
+ *
+ * This memory block can potentially out-live the driver's remove() callback,
+ * so we take a device reference to ensure its lifetime. The reference is
+ * dropped in the destructor.
+ */
 static int
 nvkm_gsp_mem_ctor(struct nvkm_gsp *gsp, size_t size, struct nvkm_gsp_mem *mem)
 {
-	mem->size = size;
 	mem->data = dma_alloc_coherent(gsp->subdev.device->dev, size, &mem->addr, GFP_KERNEL);
 	if (WARN_ON(!mem->data))
 		return -ENOMEM;
 
+	mem->size = size;
+	mem->dev = get_device(gsp->subdev.device->dev);
+
 	return 0;
 }
 
@@ -1054,8 +1070,8 @@ r535_gsp_postinit(struct nvkm_gsp *gsp)
 	nvkm_wr32(device, 0x110004, 0x00000040);
 
 	/* Release the DMA buffers that were needed only for boot and init */
-	nvkm_gsp_mem_dtor(gsp, &gsp->boot.fw);
-	nvkm_gsp_mem_dtor(gsp, &gsp->libos);
+	nvkm_gsp_mem_dtor(&gsp->boot.fw);
+	nvkm_gsp_mem_dtor(&gsp->libos);
 
 	return ret;
 }
@@ -2234,8 +2250,8 @@ static void
 nvkm_gsp_radix3_dtor(struct nvkm_gsp *gsp, struct nvkm_gsp_radix3 *rx3)
 {
 	nvkm_gsp_sg_free(gsp->subdev.device, &rx3->lvl2);
-	nvkm_gsp_mem_dtor(gsp, &rx3->lvl1);
-	nvkm_gsp_mem_dtor(gsp, &rx3->lvl0);
+	nvkm_gsp_mem_dtor(&rx3->lvl1);
+	nvkm_gsp_mem_dtor(&rx3->lvl0);
 }
 
 /**
@@ -2323,9 +2339,9 @@ nvkm_gsp_radix3_sg(struct nvkm_gsp *gsp, struct sg_table *sgt, u64 size,
 
 	if (ret) {
 lvl2_fail:
-		nvkm_gsp_mem_dtor(gsp, &rx3->lvl1);
+		nvkm_gsp_mem_dtor(&rx3->lvl1);
 lvl1_fail:
-		nvkm_gsp_mem_dtor(gsp, &rx3->lvl0);
+		nvkm_gsp_mem_dtor(&rx3->lvl0);
 	}
 
 	return ret;
@@ -2417,7 +2433,7 @@ r535_gsp_init(struct nvkm_gsp *gsp)
 
 done:
 	if (gsp->sr.meta.data) {
-		nvkm_gsp_mem_dtor(gsp, &gsp->sr.meta);
+		nvkm_gsp_mem_dtor(&gsp->sr.meta);
 		nvkm_gsp_radix3_dtor(gsp, &gsp->sr.radix3);
 		nvkm_gsp_sg_free(gsp->subdev.device, &gsp->sr.sgt);
 		return ret;
@@ -2498,7 +2514,7 @@ r535_gsp_dtor(struct nvkm_gsp *gsp)
 	mutex_destroy(&gsp->client_id.mutex);
 
 	nvkm_gsp_radix3_dtor(gsp, &gsp->radix3);
-	nvkm_gsp_mem_dtor(gsp, &gsp->sig);
+	nvkm_gsp_mem_dtor(&gsp->sig);
 	nvkm_firmware_dtor(&gsp->fw);
 
 	nvkm_falcon_fw_dtor(&gsp->booter.unload);
@@ -2509,12 +2525,12 @@ r535_gsp_dtor(struct nvkm_gsp *gsp)
 
 	r535_gsp_dtor_fws(gsp);
 
-	nvkm_gsp_mem_dtor(gsp, &gsp->rmargs);
-	nvkm_gsp_mem_dtor(gsp, &gsp->wpr_meta);
-	nvkm_gsp_mem_dtor(gsp, &gsp->shm.mem);
-	nvkm_gsp_mem_dtor(gsp, &gsp->loginit);
-	nvkm_gsp_mem_dtor(gsp, &gsp->logintr);
-	nvkm_gsp_mem_dtor(gsp, &gsp->logrm);
+	nvkm_gsp_mem_dtor(&gsp->rmargs);
+	nvkm_gsp_mem_dtor(&gsp->wpr_meta);
+	nvkm_gsp_mem_dtor(&gsp->shm.mem);
+	nvkm_gsp_mem_dtor(&gsp->loginit);
+	nvkm_gsp_mem_dtor(&gsp->logintr);
+	nvkm_gsp_mem_dtor(&gsp->logrm);
 }
 
 int