[Copybara Auto Merge]

gxp: Protect telemetry status in vd start/stop
Bug: 234674375

GitOrigin-RevId: 5240c24d481643bb6836a6ee05c28d03d12dc152
Change-Id: I851bff5b6446ee684b2d9776a6f74bdbf99b2598

2 files changed, 30 insertions, 7 deletions

diff --git a/gxp-telemetry.c b/gxp-telemetry.c
index 93b301b..7eb18cb 100644
--- a/gxp-telemetry.c
+++ b/gxp-telemetry.c
@@ -390,6 +390,11 @@ int gxp_telemetry_enable(struct gxp_dev *gxp, u8 type)
 	uint core, virt_core;
 	struct gxp_virtual_device *vd;
 
+	/*
+	 * `vd_semaphore` cannot be acquired while holding the telemetry lock,
+	 * so acquire it here before locking the telemetry lock.
+	 */
+	down_read(&gxp->vd_semaphore);
 	mutex_lock(&gxp->telemetry_mgr->lock);
 
 	switch (type) {
@@ -410,7 +415,6 @@ int gxp_telemetry_enable(struct gxp_dev *gxp, u8 type)
 	}
 
 	/* Map the buffers for any cores already running */
-	down_read(&gxp->vd_semaphore);
 	for (core = 0; core < GXP_NUM_CORES; core++) {
 		vd = gxp->core_to_vd[core];
 		if (vd != NULL) {
@@ -438,7 +442,7 @@ int gxp_telemetry_enable(struct gxp_dev *gxp, u8 type)
 	refcount_inc(&data->ref_count);
 	data->is_enabled = true;
 
-	goto up_sem;
+	goto out;
 err:
 	while (core--) {
 		vd = gxp->core_to_vd[core];
@@ -450,10 +454,9 @@ err:
 		}
 	}
 
-up_sem:
-	up_read(&gxp->vd_semaphore);
 out:
 	mutex_unlock(&gxp->telemetry_mgr->lock);
+	up_read(&gxp->vd_semaphore);
 
 	return ret;
 }
@@ -499,7 +502,14 @@ static int notify_core_and_wait_for_disable(struct gxp_dev *gxp, uint core,
 				   msecs_to_jiffies(10));
 		retries_left--;
 
+		/*
+		 * No function may attempt to acquire the `vd_semaphore` while
+		 * holding the telemetry lock, so it must be released, then
+		 * re-acquired once the `vd_semaphore` is held.
+		 */
+		mutex_unlock(&gxp->telemetry_mgr->lock);
 		down_read(&gxp->vd_semaphore);
+		mutex_lock(&gxp->telemetry_mgr->lock);
 	}
 
 	/*
@@ -604,13 +614,17 @@ int gxp_telemetry_disable(struct gxp_dev *gxp, u8 type)
 {
 	int ret;
 
-	mutex_lock(&gxp->telemetry_mgr->lock);
+	/*
+	 * `vd_semaphore` cannot be acquired while holding the telemetry lock,
+	 * so acquire it here before locking the telemetry lock.
+	 */
 	down_read(&gxp->vd_semaphore);
+	mutex_lock(&gxp->telemetry_mgr->lock);
 
 	ret = telemetry_disable_locked(gxp, type);
 
-	up_read(&gxp->vd_semaphore);
 	mutex_unlock(&gxp->telemetry_mgr->lock);
+	up_read(&gxp->vd_semaphore);
 
 	return ret;
 }
diff --git a/gxp-vd.c b/gxp-vd.c
index 70a4f18..ae07455 100644
--- a/gxp-vd.c
+++ b/gxp-vd.c
@@ -166,6 +166,8 @@ static int map_telemetry_buffers(struct gxp_dev *gxp,
 	int ret = 0;
 	struct buffer_data *buff_data;
 
+	mutex_lock(&gxp->telemetry_mgr->lock);
+
 	/* Map logging buffers if logging is enabled */
 	buff_data = gxp->telemetry_mgr->logging_buff_data;
 	if (buff_data && buff_data->is_enabled) {
@@ -174,7 +176,7 @@ static int map_telemetry_buffers(struct gxp_dev *gxp,
 			buff_data->size, buff_data->buffer_daddrs[core], 0);
 		/* Don't bother checking tracing if logging fails */
 		if (ret)
-			return ret;
+			goto out;
 	}
 
 	/* Map tracing buffers if tracing is enabled */
@@ -194,6 +196,9 @@ static int map_telemetry_buffers(struct gxp_dev *gxp,
 		}
 	}
 
+out:
+	mutex_unlock(&gxp->telemetry_mgr->lock);
+
 	return ret;
 }
 
@@ -203,6 +208,8 @@ static void unmap_telemetry_buffers(struct gxp_dev *gxp,
 {
 	struct buffer_data *buff_data;
 
+	mutex_lock(&gxp->telemetry_mgr->lock);
+
 	buff_data = gxp->telemetry_mgr->logging_buff_data;
 	if (buff_data && buff_data->is_enabled)
 		gxp_dma_unmap_allocated_coherent_buffer(
@@ -214,6 +221,8 @@ static void unmap_telemetry_buffers(struct gxp_dev *gxp,
 		gxp_dma_unmap_allocated_coherent_buffer(
 			gxp, vd, BIT(virt_core), buff_data->size,
 			buff_data->buffer_daddrs[core]);
+
+	mutex_unlock(&gxp->telemetry_mgr->lock);
 }
 
 static int map_debug_dump_buffer(struct gxp_dev *gxp,