mmc: core: Add basic support for inline encryption

In preparation for adding CQHCI crypto engine (inline encryption)
support, add the code required to make mmc_core and mmc_block aware of
inline encryption. Specifically:

- Add a capability flag MMC_CAP2_CRYPTO to struct mmc_host. Drivers
will set this if the host and driver support inline encryption.

- Embed a blk_keyslot_manager in struct mmc_host. Drivers will
initialize this (as a device-managed resource) if the host and driver
support inline encryption. mmc_block registers this keyslot manager
with the request_queue of any MMC card attached to the host.

- Make mmc_block copy the crypto keyslot and crypto data unit number
from struct request to struct mmc_request, so that drivers will have
access to them.

- If the MMC host is reset, reprogram all the keyslots to ensure that
the software state stays in sync with the hardware state.

Co-developed-by: Satya Tangirala <[e-mail]>
Signed-off-by: Satya Tangirala <[e-mail]>
Acked-by: Adrian Hunter <[e-mail]>
Reviewed-by: Satya Tangirala <[e-mail]>
Reviewed-and-tested-by: Peng Zhou <[e-mail]>
Signed-off-by: Eric Biggers <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/mmc/core/Kconfig

···
 	  This driver is only of interest to those developing or
 	  testing a host driver. Most people should say N here.
 
+config MMC_CRYPTO
+	bool "MMC Crypto Engine Support"
+	depends on BLK_INLINE_ENCRYPTION
+	help
+	  Enable Crypto Engine Support in MMC.
+	  Enabling this makes it possible for the kernel to use the crypto
+	  capabilities of the MMC device (if present) to perform crypto
+	  operations on data being transferred to/from the device.

drivers/mmc/core/Makefile

···
 mmc_block-objs			:= block.o queue.o
 obj-$(CONFIG_MMC_TEST)		+= mmc_test.o
 obj-$(CONFIG_SDIO_UART)		+= sdio_uart.o
+mmc_core-$(CONFIG_MMC_CRYPTO)	+= crypto.o

drivers/mmc/core/block.c

···
 #include "block.h"
 #include "core.h"
 #include "card.h"
+#include "crypto.h"
 #include "host.h"
 #include "bus.h"
 #include "mmc_ops.h"
···
 		    (md->flags & MMC_BLK_REL_WR);
 
 	memset(brq, 0, sizeof(struct mmc_blk_request));
+
+	mmc_crypto_prepare_req(mqrq);
 
 	brq->mrq.data = &brq->data;
 	brq->mrq.tag = req->tag;

drivers/mmc/core/core.c

···
 
 #include "core.h"
 #include "card.h"
+#include "crypto.h"
 #include "bus.h"
 #include "host.h"
 #include "sdio_bus.h"
···
 		host->ops->hs400_enhanced_strobe(host, &host->ios);
 
 	mmc_set_ios(host);
+
+	mmc_crypto_set_initial_state(host);
 }
 
 /**

drivers/mmc/core/crypto.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MMC crypto engine (inline encryption) support
+ *
+ * Copyright 2020 Google LLC
+ */
+
+#include <linux/blk-crypto.h>
+#include <linux/mmc/host.h>
+
+#include "core.h"
+#include "crypto.h"
+#include "queue.h"
+
+void mmc_crypto_set_initial_state(struct mmc_host *host)
+{
+	/* Reset might clear all keys, so reprogram all the keys. */
+	if (host->caps2 & MMC_CAP2_CRYPTO)
+		blk_ksm_reprogram_all_keys(&host->ksm);
+}
+
+void mmc_crypto_setup_queue(struct request_queue *q, struct mmc_host *host)
+{
+	if (host->caps2 & MMC_CAP2_CRYPTO)
+		blk_ksm_register(&host->ksm, q);
+}
+EXPORT_SYMBOL_GPL(mmc_crypto_setup_queue);
+
+void mmc_crypto_prepare_req(struct mmc_queue_req *mqrq)
+{
+	struct request *req = mmc_queue_req_to_req(mqrq);
+	struct mmc_request *mrq = &mqrq->brq.mrq;
+
+	if (!req->crypt_keyslot)
+		return;
+
+	mrq->crypto_enabled = true;
+	mrq->crypto_key_slot = blk_ksm_get_slot_idx(req->crypt_keyslot);
+
+	/*
+	 * For now we assume that all MMC drivers set max_dun_bytes_supported=4,
+	 * which is the limit for CQHCI crypto.  So all DUNs should be 32-bit.
+	 */
+	WARN_ON_ONCE(req->crypt_ctx->bc_dun[0] > U32_MAX);
+
+	mrq->data_unit_num = req->crypt_ctx->bc_dun[0];
+}
+EXPORT_SYMBOL_GPL(mmc_crypto_prepare_req);

drivers/mmc/core/crypto.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * MMC crypto engine (inline encryption) support
+ *
+ * Copyright 2020 Google LLC
+ */
+
+#ifndef _MMC_CORE_CRYPTO_H
+#define _MMC_CORE_CRYPTO_H
+
+struct mmc_host;
+struct mmc_queue_req;
+struct request_queue;
+
+#ifdef CONFIG_MMC_CRYPTO
+
+void mmc_crypto_set_initial_state(struct mmc_host *host);
+
+void mmc_crypto_setup_queue(struct request_queue *q, struct mmc_host *host);
+
+void mmc_crypto_prepare_req(struct mmc_queue_req *mqrq);
+
+#else /* CONFIG_MMC_CRYPTO */
+
+static inline void mmc_crypto_set_initial_state(struct mmc_host *host)
+{
+}
+
+static inline void mmc_crypto_setup_queue(struct request_queue *q,
+					  struct mmc_host *host)
+{
+}
+
+static inline void mmc_crypto_prepare_req(struct mmc_queue_req *mqrq)
+{
+}
+
+#endif /* !CONFIG_MMC_CRYPTO */
+
+#endif /* _MMC_CORE_CRYPTO_H */

drivers/mmc/core/host.c

···
 #include <linux/mmc/slot-gpio.h>
 
 #include "core.h"
+#include "crypto.h"
 #include "host.h"
 #include "slot-gpio.h"
 #include "pwrseq.h"

drivers/mmc/core/queue.c

···
 #include "block.h"
 #include "core.h"
 #include "card.h"
+#include "crypto.h"
 #include "host.h"
 
 #define MMC_DMA_MAP_MERGE_SEGMENTS	512
···
 	mutex_init(&mq->complete_lock);
 
 	init_waitqueue_head(&mq->wait);
+
+	mmc_crypto_setup_queue(mq->queue, host);
 }
 
 static inline bool mmc_merge_capable(struct mmc_host *host)

include/linux/mmc/core.h

···
 	bool			cap_cmd_during_tfr;
 
 	int			tag;
+
+#ifdef CONFIG_MMC_CRYPTO
+	bool			crypto_enabled;
+	int			crypto_key_slot;
+	u32			data_unit_num;
+#endif
 };
 
 struct mmc_card;

include/linux/mmc/host.h

···
 #include <linux/mmc/card.h>
 #include <linux/mmc/pm.h>
 #include <linux/dma-direction.h>
+#include <linux/keyslot-manager.h>
 
 struct mmc_ios {
 	unsigned int	clock;			/* clock rate */
···
 #define MMC_CAP2_CQE_DCMD	(1 << 24)	/* CQE can issue a direct command */
 #define MMC_CAP2_AVOID_3_3V	(1 << 25)	/* Host must negotiate down from 3.3V */
 #define MMC_CAP2_MERGE_CAPABLE	(1 << 26)	/* Host can merge a segment over the segment size */
+#ifdef CONFIG_MMC_CRYPTO
+#define MMC_CAP2_CRYPTO		(1 << 27)	/* Host supports inline encryption */
+#else
+#define MMC_CAP2_CRYPTO		0
+#endif
 
 	int			fixed_drv_type;	/* fixed driver type for non-removable media */
 
···
 	int			cqe_qdepth;
 	bool			cqe_enabled;
 	bool			cqe_on;
+
+	/* Inline encryption support */
+#ifdef CONFIG_MMC_CRYPTO
+	struct blk_keyslot_manager ksm;
+#endif
 
 	/* Host Software Queue support */
 	bool			hsq_enabled;