linux-kernel - [PATCH v4 13/15] firmware: qcom: tzmem: enable SHM Bridge support

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Message-Id: <20231013114843.63205-14-brgl@bgdev.pl>
Date:   Fri, 13 Oct 2023 13:48:41 +0200
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>
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>
Subject: [PATCH v4 13/15] 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>
---
 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 237da40de832..e01407e31ae4 100644
--- a/drivers/firmware/qcom/Kconfig
+++ b/drivers/firmware/qcom/Kconfig
@@ -27,6 +27,16 @@ 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 68ca59c5598e..6c4f29a00f26 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");
+		ret = 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.
-- 
2.39.2