[PATCH v1 02/11] soc: qcom: add crypto_virt backend for virtio-blk inline crypto

[Linlin Zhang <linlin.zhang@oss.qualcomm.com>]

From: linlzhan <linlin.zhang@oss.qualcomm.com>

In a Qualcomm GVM environment the ICE hardware is controlled by the
host, GVM has no direct access to it. So, key operation in GVM is
done through SCM calls rather than direct register access. In this
way the access to ICE registers are offloaded to Trust Zone.

Add QCOM_CRYPTO_VIRT, which implements struct virtblk_crypto_variant_ops
for the virtio_blk_crypto_ext dispatch layer. It maps keyslot
program/evict to qcom_scm_ice_set_key() and
qcom_scm_ice_invalidate_key(), and software-secret derivation to
qcom_scm_derive_sw_secret().

Signed-off-by: linlzhan <linlin.zhang@oss.qualcomm.com>
---
 drivers/soc/qcom/Kconfig       | 12 +++++
 drivers/soc/qcom/Makefile      |  1 +
 drivers/soc/qcom/crypto_virt.c | 89 ++++++++++++++++++++++++++++++++++
 3 files changed, 102 insertions(+)
 create mode 100644 drivers/soc/qcom/crypto_virt.c

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 2b524154d9fb..6c632d114d45 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -298,6 +298,18 @@ config QCOM_INLINE_CRYPTO_ENGINE
 	tristate
 	select QCOM_SCM
 
+config QCOM_CRYPTO_VIRT
+	tristate "Qualcomm Technologies, Inc. Crypto Virt driver"
+	depends on VIRTBLK_CRYPTO_VIRTUALIZATION
+	depends on QCOM_SCM
+	default VIRTBLK_CRYPTO_VIRTUALIZATION if ARCH_QCOM
+	help
+	  GVM-side hardware-wrapped-key SCM operations exposed to
+	  virtio_blk's inline crypto layer: per-slot key programming and
+	  eviction, and key derive/generate/prepare/import.
+	  Say Y here to compile the driver as a part of kernel or M to compile
+	  as a module.
+
 config QCOM_KRYO_L2_ACCESSORS
 	bool
 	depends on ARM64
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index 798643be3590..6d4b7546d1fb 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -39,5 +39,6 @@ obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=	kryo-l2-accessors.o
 obj-$(CONFIG_QCOM_ICC_BWMON)	+= icc-bwmon.o
 qcom_ice-objs			+= ice.o
 obj-$(CONFIG_QCOM_INLINE_CRYPTO_ENGINE)	+= qcom_ice.o
+obj-$(CONFIG_QCOM_CRYPTO_VIRT)	+= crypto_virt.o
 obj-$(CONFIG_QCOM_PBS) +=	qcom-pbs.o
 obj-$(CONFIG_QCOM_UBWC_CONFIG) += ubwc_config.o
diff --git a/drivers/soc/qcom/crypto_virt.c b/drivers/soc/qcom/crypto_virt.c
new file mode 100644
index 000000000000..4ee2a36af6c1
--- /dev/null
+++ b/drivers/soc/qcom/crypto_virt.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/blk-crypto.h>
+#include <linux/virtio_blk_crypto_ext.h>
+#include <linux/firmware/qcom/qcom_scm.h>
+
+static int crypto_virt_program_key(const struct blk_crypto_key *key,
+				   unsigned int slot)
+{
+	u32 dus_512_units;
+	int ret;
+
+	if (!key || !key->size) {
+		pr_err("%s: invalid key\n", __func__);
+		return -EINVAL;
+	}
+
+	/* Only AES-256-XTS has been tested so far. */
+	if (key->crypto_cfg.crypto_mode !=
+	    BLK_ENCRYPTION_MODE_AES_256_XTS) {
+		pr_err_ratelimited("Unsupported crypto mode: %d\n",
+				    key->crypto_cfg.crypto_mode);
+		return -EINVAL;
+	}
+
+	/* qcom_scm_ice_set_key()'s data_unit_size is expressed in 512-byte units */
+	dus_512_units = key->crypto_cfg.data_unit_size / 512;
+
+	ret = qcom_scm_ice_set_key(slot, key->bytes, key->size,
+		QCOM_SCM_ICE_CIPHER_AES_256_XTS, dus_512_units);
+	if (ret)
+		pr_err("%s: slot=%u ret=%d\n", __func__, slot, ret);
+
+	return ret;
+}
+
+static int crypto_virt_invalidate_key(unsigned int slot)
+{
+	int ret;
+
+	ret = qcom_scm_ice_invalidate_key(slot);
+	if (ret)
+		pr_err("%s: slot=%u ret=%d\n", __func__, slot, ret);
+
+	return ret;
+}
+
+static int crypto_virt_derive_sw_secret_key(const u8 *eph_key, size_t eph_key_size,
+					    u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE])
+{
+	int ret;
+
+	ret = qcom_scm_derive_sw_secret(eph_key, eph_key_size,
+					sw_secret, BLK_CRYPTO_SW_SECRET_SIZE);
+	if (ret == -EIO || ret == -EINVAL)
+		ret = -EBADMSG; /* probably invalid key */
+
+	if (ret)
+		pr_err("%s: ret=%d\n", __func__, ret);
+
+	return ret;
+}
+
+static struct virtblk_crypto_variant_ops virtblk_crypto_qcom_vops = {
+	.owner = THIS_MODULE,
+	.program_key = crypto_virt_program_key,
+	.evict_key = crypto_virt_invalidate_key,
+	.derive_sw_secret_key = crypto_virt_derive_sw_secret_key,
+};
+
+static int __init crypto_virt_init(void)
+{
+	virtblk_set_crypto_ops(&virtblk_crypto_qcom_vops);
+	return 0;
+}
+module_init(crypto_virt_init);
+
+#if IS_MODULE(CONFIG_QCOM_CRYPTO_VIRT)
+static void __exit crypto_virt_exit(void)
+{
+	virtblk_set_crypto_ops(NULL);
+}
+module_exit(crypto_virt_exit);
+#endif
+
+MODULE_DESCRIPTION("Qualcomm Technologies, Inc. Crypto Virt Driver");
+MODULE_LICENSE("GPL");
-- 
2.34.1