[PATCH V3 05/10] remoteproc: qcom_q6v5_mss: Use a carveout to authenticate modem headers

Sibi Sankar
2023-01-11T11:46:37Z

Any access to the dynamically allocated metadata region by the application
processor after assigning it to the remote Q6 will result in a XPU
violation. Fix this by replacing the dynamically allocated memory region
with a no-map carveout and unmap the modem metadata memory region before
passing control to the remote Q6.

Reported-and-tested-by: Amit Pundir <amit.pundir@linaro.org>
Fixes: 6c5a9dc2481b ("remoteproc: qcom: Make secure world call for mem ownership switch")
Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
---

v3:
* Drop revert no_kernel_mapping since it's already on the list [Mani]
* kfree metadata from the branch for parity

drivers/remoteproc/qcom_q6v5_mss.c | 48 ++++++++++++++++++++++++++----
1 file changed, 42 insertions(+), 6 deletions(-)

diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
index e2f765f87ec9..e25d44e20ae7 100644
--- a/drivers/remoteproc/qcom_q6v5_mss.c
+++ b/drivers/remoteproc/qcom_q6v5_mss.c
@@ -215,6 +215,7 @@ struct q6v5 {
size_t mba_size;
size_t dp_size;

+ phys_addr_t mdata_phys;
phys_addr_t mpss_phys;
phys_addr_t mpss_reloc;
size_t mpss_size;
@@ -973,15 +974,29 @@ static int q6v5_mpss_init_image(struct q6v5 *qproc, const struct firmware *fw,
if (IS_ERR(metadata))
return PTR_ERR(metadata);

- ptr = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
- if (!ptr) {
- kfree(metadata);
- dev_err(qproc->dev, "failed to allocate mdt buffer\n");
- return -ENOMEM;
+ if (qproc->mdata_phys) {
+ phys = qproc->mdata_phys;
+ ptr = memremap(qproc->mdata_phys, size, MEMREMAP_WC);
+ if (!ptr) {
+ kfree(metadata);
+ dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n",
+ &qproc->mdata_phys, size);
+ return -EBUSY;
+ }
+ } else {
+ ptr = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
+ if (!ptr) {
+ kfree(metadata);
+ dev_err(qproc->dev, "failed to allocate mdt buffer\n");
+ return -ENOMEM;
+ }
}

memcpy(ptr, metadata, size);

+ if (qproc->mdata_phys)
+ memunmap(ptr);
+
/* Hypervisor mapping to access metadata by modem */
mdata_perm = BIT(QCOM_SCM_VMID_HLOS);
ret = q6v5_xfer_mem_ownership(qproc, &mdata_perm, false, true,
@@ -1010,7 +1025,8 @@ static int q6v5_mpss_init_image(struct q6v5 *qproc, const struct firmware *fw,
"mdt buffer not reclaimed system may become unstable\n");

free_dma_attrs:
- dma_free_attrs(qproc->dev, size, ptr, phys, dma_attrs);
+ if (!qproc->mdata_phys)
+ dma_free_attrs(qproc->dev, size, ptr, phys, dma_attrs);
kfree(metadata);

return ret < 0 ? ret : 0;
@@ -1893,6 +1909,26 @@ static int q6v5_alloc_memory_region(struct q6v5 *qproc)
qproc->mpss_phys = qproc->mpss_reloc = r.start;
qproc->mpss_size = resource_size(&r);

+ if (!child) {
+ node = of_parse_phandle(qproc->dev->of_node, "memory-region", 2);
+ } else {
+ child = of_get_child_by_name(qproc->dev->of_node, "metadata");
+ node = of_parse_phandle(child, "memory-region", 0);
+ of_node_put(child);
+ }
+
+ if (!node)
+ return 0;
+
+ ret = of_address_to_resource(node, 0, &r);
+ of_node_put(node);
+ if (ret) {
+ dev_err(qproc->dev, "unable to resolve metadata region\n");
+ return ret;
+ }
+
+ qproc->mdata_phys = r.start;
+
return 0;
}

--
2.17.1