ANDROID: mmc: support hardware that takes key directly

Currently when an MMC host driver declares crypto support, the MMC core passes a keyslot and 32-bit DUN down to the driver in each request. This is enough for the "standard" eMMC v5.2 crypto (cqhci-crypto). However some SoCs don't follow this standard. They don't have keyslots but rather take keys directly, and they support longer DUNs. To allow such hardware to be supported, modify the MMC core to pass a pointer to the bio_crypt_ctx along with each request, replacing the crypto_enabled and data_unit_num fields. This way is more flexible. Also update cqhci-crypto accordingly to keep it working. (Not being sent upstream yet because this isn't really useful by itself; it would need support for hardware that needs it to be upstreamed too.) Bug: 180886435 Bug: 182283899 Change-Id: I8faf3135f570ca3f2798cf812b4245a5df5515ba Signed-off-by: Eric Biggers <[email protected]>
sourajitk · Mar 16, 2021 · 6c6fac8 · 6c6fac8
1 parent e4636b4
commit 6c6fac8
Show file tree

Hide file tree

Showing 3 changed files with 10 additions and 15 deletions.
diff --git a/drivers/mmc/core/crypto.c b/drivers/mmc/core/crypto.c
@@ -31,18 +31,11 @@ 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)
+	if (!req->crypt_ctx)
 		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];
+	mrq->crypto_ctx = req->crypt_ctx;
+	if (req->crypt_keyslot)
+		mrq->crypto_key_slot = blk_ksm_get_slot_idx(req->crypt_keyslot);
 }
 EXPORT_SYMBOL_GPL(mmc_crypto_prepare_req);
diff --git a/drivers/mmc/host/cqhci-crypto.h b/drivers/mmc/host/cqhci-crypto.h
@@ -22,12 +22,15 @@ int cqhci_crypto_init(struct cqhci_host *host);
  */
 static inline u64 cqhci_crypto_prep_task_desc(struct mmc_request *mrq)
 {
-	if (!mrq->crypto_enabled)
+	if (!mrq->crypto_ctx)
 		return 0;
 
+	/* We set max_dun_bytes_supported=4, so all DUNs should be 32-bit. */
+	WARN_ON_ONCE(mrq->crypto_ctx->bc_dun[0] > U32_MAX);
+
 	return CQHCI_CRYPTO_ENABLE_BIT |
 	       CQHCI_CRYPTO_KEYSLOT(mrq->crypto_key_slot) |
-	       mrq->data_unit_num;
+	       mrq->crypto_ctx->bc_dun[0];
 }
 
 #else /* CONFIG_MMC_CRYPTO */

diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
@@ -164,9 +164,8 @@ struct mmc_request {
 	int			tag;
 
 #ifdef CONFIG_MMC_CRYPTO
-	bool			crypto_enabled;
+	const struct bio_crypt_ctx *crypto_ctx;
 	int			crypto_key_slot;
-	u32			data_unit_num;
 #endif
 };