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 <satyat@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Satya Tangirala <satyat@google.com>
Reviewed-and-tested-by: Peng Zhou <peng.zhou@mediatek.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20210126001456.382989-2-ebiggers@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/drivers/mmc/core/crypto.c b/drivers/mmc/core/crypto.c
new file mode 100644
index 000000000000..419a368f8402
--- /dev/null
+++ b/drivers/mmc/core/crypto.c
@@ -0,0 +1,48 @@
+// 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);