firmware: qcom: uefisecapp: Fix memory related IO errors and crashes

It turns out that while the QSEECOM APP_SEND command has specific fields
for request and response buffers, uefisecapp expects them both to be in
a single memory region. Failure to adhere to this has (so far) resulted
in either no response being written to the response buffer (causing an
EIO to be emitted down the line), the SCM call to fail with EINVAL
(i.e., directly from TZ/firmware), or the device to be hard-reset.

While this issue can be triggered deterministically, in the current form
it seems to happen rather sporadically (which is why it has gone
unnoticed during earlier testing). This is likely due to the two
kzalloc() calls (for request and response) being directly after each
other. Which means that those likely return consecutive regions most of
the time, especially when not much else is going on in the system.

Fix this by allocating a single memory region for both request and
response buffers, properly aligning both structs inside it. This
unfortunately also means that the qcom_scm_qseecom_app_send() interface
needs to be restructured, as it should no longer map the DMA regions
separately. Therefore, move the responsibility of DMA allocation (or
mapping) to the caller.

Fixes: 759e7a2b62eb ("firmware: Add support for Qualcomm UEFI Secure Application")
Cc: stable@vger.kernel.org  # 6.7
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Tested-by: Konrad Dybcio <konrad.dybcio@linaro.org> # X13s
Link: https://lore.kernel.org/r/20240406130125.1047436-1-luzmaximilian@gmail.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

1 files changed, 6 insertions, 31 deletions

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index 520de9b5633a..90283f160a22 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -1576,9 +1576,9 @@ EXPORT_SYMBOL_GPL(qcom_scm_qseecom_app_get_id);
 /**
  * qcom_scm_qseecom_app_send() - Send to and receive data from a given QSEE app.
  * @app_id:   The ID of the target app.
- * @req:      Request buffer sent to the app (must be DMA-mappable).
+ * @req:      DMA address of the request buffer sent to the app.
  * @req_size: Size of the request buffer.
- * @rsp:      Response buffer, written to by the app (must be DMA-mappable).
+ * @rsp:      DMA address of the response buffer, written to by the app.
  * @rsp_size: Size of the response buffer.
  *
  * Sends a request to the QSEE app associated with the given ID and read back
@@ -1589,33 +1589,13 @@ EXPORT_SYMBOL_GPL(qcom_scm_qseecom_app_get_id);
  *
  * Return: Zero on success, nonzero on failure.
  */
-int qcom_scm_qseecom_app_send(u32 app_id, void *req, size_t req_size, void *rsp,
-			      size_t rsp_size)
+int qcom_scm_qseecom_app_send(u32 app_id, dma_addr_t req, size_t req_size,
+			      dma_addr_t rsp, size_t rsp_size)
 {
 	struct qcom_scm_qseecom_resp res = {};
 	struct qcom_scm_desc desc = {};
-	dma_addr_t req_phys;
-	dma_addr_t rsp_phys;
 	int status;
 
-	/* Map request buffer */
-	req_phys = dma_map_single(__scm->dev, req, req_size, DMA_TO_DEVICE);
-	status = dma_mapping_error(__scm->dev, req_phys);
-	if (status) {
-		dev_err(__scm->dev, "qseecom: failed to map request buffer\n");
-		return status;
-	}
-
-	/* Map response buffer */
-	rsp_phys = dma_map_single(__scm->dev, rsp, rsp_size, DMA_FROM_DEVICE);
-	status = dma_mapping_error(__scm->dev, rsp_phys);
-	if (status) {
-		dma_unmap_single(__scm->dev, req_phys, req_size, DMA_TO_DEVICE);
-		dev_err(__scm->dev, "qseecom: failed to map response buffer\n");
-		return status;
-	}
-
-	/* Set up SCM call data */
 	desc.owner = QSEECOM_TZ_OWNER_TZ_APPS;
 	desc.svc = QSEECOM_TZ_SVC_APP_ID_PLACEHOLDER;
 	desc.cmd = QSEECOM_TZ_CMD_APP_SEND;
@@ -1623,18 +1603,13 @@ int qcom_scm_qseecom_app_send(u32 app_id, void *req, size_t req_size, void *rsp,
 				     QCOM_SCM_RW, QCOM_SCM_VAL,
 				     QCOM_SCM_RW, QCOM_SCM_VAL);
 	desc.args[0] = app_id;
-	desc.args[1] = req_phys;
+	desc.args[1] = req;
 	desc.args[2] = req_size;
-	desc.args[3] = rsp_phys;
+	desc.args[3] = rsp;
 	desc.args[4] = rsp_size;
 
-	/* Perform call */
 	status = qcom_scm_qseecom_call(&desc, &res);
 
-	/* Unmap buffers */
-	dma_unmap_single(__scm->dev, rsp_phys, rsp_size, DMA_FROM_DEVICE);
-	dma_unmap_single(__scm->dev, req_phys, req_size, DMA_TO_DEVICE);
-
 	if (status)
 		return status;