remoteproc: qcom_q6v5_mss: map/unmap MBA region before/after use

The application processor accessing the MBA region after assigning it to
the remote Q6 would lead to an XPU violation. Fix this by un-mapping the
MBA region post firmware copy and MBA text log dumps.
Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
Link: https://lore.kernel.org/r/1604473422-29639-2-git-send-email-sibis@codeaurora.org
[bjorn: Renamed "ptr" to "mba_region"]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/qcom_q6v5_mss.c

@@ -189,7 +189,6 @@ struct q6v5 {
 	size_t total_dump_size;
 
 	phys_addr_t mba_phys;
-	void *mba_region;
 	size_t mba_size;
 	size_t dp_size;
 
@@ -408,7 +407,7 @@ static int q6v5_xfer_mem_ownership(struct q6v5 *qproc, int *current_perm,
 				   current_perm, next, perms);
 }
 
-static void q6v5_debug_policy_load(struct q6v5 *qproc)
+static void q6v5_debug_policy_load(struct q6v5 *qproc, void *mba_region)
 {
 	const struct firmware *dp_fw;
 
@@ -416,7 +415,7 @@ static void q6v5_debug_policy_load(struct q6v5 *qproc)
 		return;
 
 	if (SZ_1M + dp_fw->size <= qproc->mba_size) {
-		memcpy(qproc->mba_region + SZ_1M, dp_fw->data, dp_fw->size);
+		memcpy(mba_region + SZ_1M, dp_fw->data, dp_fw->size);
 		qproc->dp_size = dp_fw->size;
 	}
 
@@ -426,6 +425,7 @@ static void q6v5_debug_policy_load(struct q6v5 *qproc)
 static int q6v5_load(struct rproc *rproc, const struct firmware *fw)
 {
 	struct q6v5 *qproc = rproc->priv;
+	void *mba_region;
 
 	/* MBA is restricted to a maximum size of 1M */
 	if (fw->size > qproc->mba_size || fw->size > SZ_1M) {
@@ -433,8 +433,16 @@ static int q6v5_load(struct rproc *rproc, const struct firmware *fw)
 		return -EINVAL;
 	}
 
-	memcpy(qproc->mba_region, fw->data, fw->size);
-	q6v5_debug_policy_load(qproc);
+	mba_region = memremap(qproc->mba_phys, qproc->mba_size, MEMREMAP_WC);
+	if (!mba_region) {
+		dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n",
+			&qproc->mba_phys, qproc->mba_size);
+		return -EBUSY;
+	}
+
+	memcpy(mba_region, fw->data, fw->size);
+	q6v5_debug_policy_load(qproc, mba_region);
+	memunmap(mba_region);
 
 	return 0;
 }
@@ -541,6 +549,7 @@ static void q6v5_dump_mba_logs(struct q6v5 *qproc)
 {
 	struct rproc *rproc = qproc->rproc;
 	void *data;
+	void *mba_region;
 
 	if (!qproc->has_mba_logs)
 		return;
@@ -549,12 +558,16 @@ static void q6v5_dump_mba_logs(struct q6v5 *qproc)
 				    qproc->mba_size))
 		return;
 
-	data = vmalloc(MBA_LOG_SIZE);
-	if (!data)
+	mba_region = memremap(qproc->mba_phys, qproc->mba_size, MEMREMAP_WC);
+	if (!mba_region)
 		return;
 
-	memcpy(data, qproc->mba_region, MBA_LOG_SIZE);
-	dev_coredumpv(&rproc->dev, data, MBA_LOG_SIZE, GFP_KERNEL);
+	data = vmalloc(MBA_LOG_SIZE);
+	if (data) {
+		memcpy(data, mba_region, MBA_LOG_SIZE);
+		dev_coredumpv(&rproc->dev, data, MBA_LOG_SIZE, GFP_KERNEL);
+	}
+	memunmap(mba_region);
 }
 
 static int q6v5proc_reset(struct q6v5 *qproc)
@@ -1605,12 +1618,6 @@ static int q6v5_alloc_memory_region(struct q6v5 *qproc)
 
 	qproc->mba_phys = r.start;
 	qproc->mba_size = resource_size(&r);
-	qproc->mba_region = devm_ioremap_wc(qproc->dev, qproc->mba_phys, qproc->mba_size);
-	if (!qproc->mba_region) {
-		dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n",
-			&r.start, qproc->mba_size);
-		return -EBUSY;
-	}
 
 	if (!child) {
 		node = of_parse_phandle(qproc->dev->of_node,