linux-kernel - [PATCH v7 10/12] firmware: qcom: tzmem: enable SHM Bridge support

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Message-Id: <20240205182810.58382-11-brgl@bgdev.pl>
Date: Mon,  5 Feb 2024 19:28:08 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Andy Gross <agross@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	Elliot Berman <quic_eberman@...cinc.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
	Guru Das Srinagesh <quic_gurus@...cinc.com>,
	Andrew Halaney <ahalaney@...hat.com>,
	Maximilian Luz <luzmaximilian@...il.com>,
	Alex Elder <elder@...aro.org>,
	Srini Kandagatla <srinivas.kandagatla@...aro.org>,
	Arnd Bergmann <arnd@...db.de>
Cc: linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	kernel@...cinc.com,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
	Deepti Jaggi <quic_djaggi@...cinc.com>
Subject: [PATCH v7 10/12] firmware: qcom: tzmem: enable SHM Bridge support

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

Add a new Kconfig option for selecting the SHM Bridge mode of operation
for the TrustZone memory allocator.

If enabled at build-time, it will still be checked for availability at
run-time. If the architecture doesn't support SHM Bridge, the allocator
will work just like in the default mode.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Tested-by: Andrew Halaney <ahalaney@...hat.com> # sc8280xp-lenovo-thinkpad-x13s
Tested-by: Deepti Jaggi <quic_djaggi@...cinc.com> #sa8775p-ride
Reviewed-by: Elliot Berman <quic_eberman@...cinc.com>
---
 drivers/firmware/qcom/Kconfig      | 10 +++++
 drivers/firmware/qcom/qcom_tzmem.c | 65 +++++++++++++++++++++++++++++-
 2 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/qcom/Kconfig b/drivers/firmware/qcom/Kconfig
index d24d83223867..af6f895c5adf 100644
--- a/drivers/firmware/qcom/Kconfig
+++ b/drivers/firmware/qcom/Kconfig
@@ -28,6 +28,16 @@ config QCOM_TZMEM_MODE_DEFAULT
 	  Use the default allocator mode. The memory is page-aligned, non-cachable
 	  and contiguous.
 
+config QCOM_TZMEM_MODE_SHMBRIDGE
+	bool "SHM Bridge"
+	help
+	  Use Qualcomm Shared Memory Bridge. The memory has the same alignment as
+	  in the 'Default' allocator but is also explicitly marked as an SHM Bridge
+	  buffer.
+
+	  With this selected, all buffers passed to the TrustZone must be allocated
+	  using the TZMem allocator or else the TrustZone will refuse to use them.
+
 endchoice
 
 config QCOM_SCM_DOWNLOAD_MODE_DEFAULT
diff --git a/drivers/firmware/qcom/qcom_tzmem.c b/drivers/firmware/qcom/qcom_tzmem.c
index 44a062f2abd4..1ca3773263e5 100644
--- a/drivers/firmware/qcom/qcom_tzmem.c
+++ b/drivers/firmware/qcom/qcom_tzmem.c
@@ -55,7 +55,70 @@ static void qcom_tzmem_cleanup_pool(struct qcom_tzmem_pool *pool)
 
 }
 
-#endif /* CONFIG_QCOM_TZMEM_MODE_DEFAULT */
+#elif IS_ENABLED(CONFIG_QCOM_TZMEM_MODE_SHMBRIDGE)
+
+#include <linux/firmware/qcom/qcom_scm.h>
+
+#define QCOM_SHM_BRIDGE_NUM_VM_SHIFT 9
+
+static bool qcom_tzmem_using_shm_bridge;
+
+static int qcom_tzmem_init(void)
+{
+	int ret;
+
+	ret = qcom_scm_shm_bridge_enable();
+	if (ret == -EOPNOTSUPP) {
+		dev_info(qcom_tzmem_dev, "SHM Bridge not supported\n");
+		return 0;
+	}
+
+	if (!ret)
+		qcom_tzmem_using_shm_bridge = true;
+
+	return ret;
+}
+
+static int qcom_tzmem_init_pool(struct qcom_tzmem_pool *pool)
+{
+	u64 pfn_and_ns_perm, ipfn_and_s_perm, size_and_flags, ns_perms;
+	int ret;
+
+	if (!qcom_tzmem_using_shm_bridge)
+		return 0;
+
+	ns_perms = (QCOM_SCM_PERM_WRITE | QCOM_SCM_PERM_READ);
+	pfn_and_ns_perm = (u64)pool->pbase | ns_perms;
+	ipfn_and_s_perm = (u64)pool->pbase | ns_perms;
+	size_and_flags = pool->size | (1 << QCOM_SHM_BRIDGE_NUM_VM_SHIFT);
+
+	u64 *handle __free(kfree) = kzalloc(sizeof(*handle), GFP_KERNEL);
+	if (!handle)
+		return -ENOMEM;
+
+	ret = qcom_scm_shm_bridge_create(qcom_tzmem_dev, pfn_and_ns_perm,
+					 ipfn_and_s_perm, size_and_flags,
+					 QCOM_SCM_VMID_HLOS, handle);
+	if (ret)
+		return ret;
+
+	pool->priv = no_free_ptr(handle);
+
+	return 0;
+}
+
+static void qcom_tzmem_cleanup_pool(struct qcom_tzmem_pool *pool)
+{
+	u64 *handle = pool->priv;
+
+	if (!qcom_tzmem_using_shm_bridge)
+		return;
+
+	qcom_scm_shm_bridge_delete(qcom_tzmem_dev, *handle);
+	kfree(handle);
+}
+
+#endif /* CONFIG_QCOM_TZMEM_MODE_SHMBRIDGE */
 
 /**
  * qcom_tzmem_pool_new() - Create a new TZ memory pool.
-- 
2.40.1