remoteproc: qcom: pas: Map/unmap subsystem region before auth_and_reset

Qualcomm remoteproc drivers such as qcom_q6v5_mss, which do not use the
Peripheral Authentication Service (PAS), always map the MBA region before
use and unmap it once the usage is complete. This behavior was introduced
to avoid issues seen in the past where speculative accesses from the
application processor to the MBA region after it was assigned to the remote
Q6 led to an XPU violation. The issue was mitigated by unmapping the region
before handing control to the remote Q6.

Currently, most Qualcomm SoCs using the PAS driver run either with a
standalone QHEE or the Gunyah hypervisor. In these environments, the
hypervisor unmaps the Q6 memory from HLOS Stage-2 and remaps it into the
Q6 Stage-2 page table. As a result, speculative accesses from HLOS cannot
reach the region even if it remains mapped in HLOS Stage-1; therefore, XPU
violations cannot occur.

However, when the same SoC runs Linux at EL2, Linux itself must perform the
unmapping to avoid such issues. It is still correct to apply this mapping/
unmapping sequence even for SoCs that run under Gunyah, so this behavior
should not be conditional.

Introduce qcom_pas_ctx_map() in qcom_pas.h to centralise the ioremap_wc
pattern used by both qcom_q6v5_pas and qcom_mdt_pas_load, and use it in
both places.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260724182858.1868271-5-mukesh.ojha@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/soc/qcom/mdt_loader.h b/include/linux/soc/qcom/mdt_loader.h
index 142409555425..74886f772d46 100644
--- a/include/linux/soc/qcom/mdt_loader.h
+++ b/include/linux/soc/qcom/mdt_loader.h
@@ -21,7 +21,7 @@ int qcom_mdt_load(struct device *dev, const struct firmware *fw,
 		  phys_addr_t *reloc_base);
 
 int qcom_mdt_pas_load(struct qcom_pas_context *ctx, const struct firmware *fw,
-		      const char *firmware, void *mem_region, phys_addr_t *reloc_base);
+		      const char *firmware, phys_addr_t *reloc_base);
 
 int qcom_mdt_load_no_init(struct device *dev, const struct firmware *fw,
 			  const char *fw_name, void *mem_region,
@@ -47,7 +47,7 @@ static inline int qcom_mdt_load(struct device *dev, const struct firmware *fw,
 
 static inline int qcom_mdt_pas_load(struct qcom_pas_context *ctx,
 				    const struct firmware *fw, const char *firmware,
-				    void *mem_region, phys_addr_t *reloc_base)
+				    phys_addr_t *reloc_base)
 {
 	return -ENODEV;
 }