crypto: tegra - Reserve keyslots to allocate dynamically

The HW supports only storing 15 keys at a time. This limits the number
of tfms that can work without failutes. Reserve keyslots to solve this
and use the reserved ones during the encryption/decryption operation.
This allow users to have the capability of hardware protected keys
and faster operations if there are limited number of tfms while not
halting the operation if there are more tfms.

Fixes: 0880bb3b00c8 ("crypto: tegra - Add Tegra Security Engine driver")
Signed-off-by: Akhil R <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/tegra/tegra-se-aes.c

···
 	u32 ivsize;
 	u32 key1_id;
 	u32 key2_id;
+	u32 keylen;
+	u8 key1[AES_MAX_KEY_SIZE];
+	u8 key2[AES_MAX_KEY_SIZE];
 };
 
 struct tegra_aes_reqctx {
···
 	struct tegra_se *se;
 	unsigned int authsize;
 	u32 alg;
-	u32 keylen;
 	u32 key_id;
+	u32 keylen;
+	u8 key[AES_MAX_KEY_SIZE];
 };
 
 struct tegra_aead_reqctx {
···
 	unsigned int cryptlen;
 	unsigned int authsize;
 	bool encrypt;
-	u32 config;
 	u32 crypto_config;
+	u32 config;
 	u32 key_id;
 	u32 iv[4];
 	u8 authdata[16];
···
 	struct tegra_se *se;
 	unsigned int alg;
 	u32 key_id;
+	u32 keylen;
+	u8 key[AES_MAX_KEY_SIZE];
 	struct crypto_shash *fallback_tfm;
 };
 
···
 	struct tegra_aes_ctx *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
 	struct tegra_aes_reqctx *rctx = skcipher_request_ctx(req);
 	struct tegra_se *se = ctx->se;
-	unsigned int cmdlen;
+	unsigned int cmdlen, key1_id, key2_id;
 	int ret;
 
 	rctx->iv = (u32 *)req->iv;
 	rctx->len = req->cryptlen;
+	key1_id = ctx->key1_id;
+	key2_id = ctx->key2_id;
 
 	/* Pad input to AES Block size */
 	if (ctx->alg != SE_ALG_XTS) {
···
 
 	scatterwalk_map_and_copy(rctx->datbuf.buf, req->src, 0, req->cryptlen, 0);
 
+	rctx->config = tegra234_aes_cfg(ctx->alg, rctx->encrypt);
+	rctx->crypto_config = tegra234_aes_crypto_cfg(ctx->alg, rctx->encrypt);
+
+	if (!key1_id) {
+		ret = tegra_key_submit_reserved_aes(ctx->se, ctx->key1,
+						    ctx->keylen, ctx->alg, &key1_id);
+		if (ret)
+			goto out;
+	}
+
+	rctx->crypto_config |= SE_AES_KEY_INDEX(key1_id);
+
+	if (ctx->alg == SE_ALG_XTS) {
+		if (!key2_id) {
+			ret = tegra_key_submit_reserved_xts(ctx->se, ctx->key2,
+							    ctx->keylen, ctx->alg, &key2_id);
+			if (ret)
+				goto out;
+		}
+
+		rctx->crypto_config |= SE_AES_KEY2_INDEX(key2_id);
+	}
+
 	/* Prepare the command and submit for execution */
 	cmdlen = tegra_aes_prep_cmd(ctx, rctx);
 	ret = tegra_se_host1x_submit(se, se->cmdbuf, cmdlen);
···
 	tegra_aes_update_iv(req, ctx);
 	scatterwalk_map_and_copy(rctx->datbuf.buf, req->dst, 0, req->cryptlen, 1);
 
+out:
 	/* Free the buffer */
 	dma_free_coherent(ctx->se->dev, rctx->datbuf.size,
 			  rctx->datbuf.buf, rctx->datbuf.addr);
+
+	if (tegra_key_is_reserved(key1_id))
+		tegra_key_invalidate_reserved(ctx->se, key1_id, ctx->alg);
+
+	if (tegra_key_is_reserved(key2_id))
+		tegra_key_invalidate_reserved(ctx->se, key2_id, ctx->alg);
 
 out_finalize:
 	crypto_finalize_skcipher_request(se->engine, req, ret);
···
 	ctx->se = se_alg->se_dev;
 	ctx->key1_id = 0;
 	ctx->key2_id = 0;
+	ctx->keylen = 0;
 
 	algname = crypto_tfm_alg_name(&tfm->base);
 	ret = se_algname_to_algid(algname);
···
 			    const u8 *key, u32 keylen)
 {
 	struct tegra_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
+	int ret;
 
 	if (aes_check_keylen(keylen)) {
 		dev_dbg(ctx->se->dev, "invalid key length (%d)\n", keylen);
 		return -EINVAL;
 	}
 
-	return tegra_key_submit(ctx->se, key, keylen, ctx->alg, &ctx->key1_id);
+	ret = tegra_key_submit(ctx->se, key, keylen, ctx->alg, &ctx->key1_id);
+	if (ret) {
+		ctx->keylen = keylen;
+		memcpy(ctx->key1, key, keylen);
+	}
+
+	return 0;
 }
 
 static int tegra_xts_setkey(struct crypto_skcipher *tfm,
···
 
 	ret = tegra_key_submit(ctx->se, key, len,
 			       ctx->alg, &ctx->key1_id);
-	if (ret)
-		return ret;
+	if (ret) {
+		ctx->keylen = len;
+		memcpy(ctx->key1, key, len);
+	}
 
-	return tegra_key_submit(ctx->se, key + len, len,
+	ret = tegra_key_submit(ctx->se, key + len, len,
 			       ctx->alg, &ctx->key2_id);
+	if (ret) {
+		ctx->keylen = len;
+		memcpy(ctx->key2, key + len, len);
+	}
 
 	return 0;
 }
···
 		req->iv = NULL;
 
 	rctx->encrypt = encrypt;
-	rctx->config = tegra234_aes_cfg(ctx->alg, encrypt);
-	rctx->crypto_config = tegra234_aes_crypto_cfg(ctx->alg, encrypt);
-	rctx->crypto_config |= SE_AES_KEY_INDEX(ctx->key1_id);
-
-	if (ctx->key2_id)
-		rctx->crypto_config |= SE_AES_KEY2_INDEX(ctx->key2_id);
 
 	return crypto_transfer_skcipher_request_to_engine(ctx->se->engine, req);
 }
···
 
 	rctx->config = tegra234_aes_cfg(SE_ALG_GMAC, rctx->encrypt);
 	rctx->crypto_config = tegra234_aes_crypto_cfg(SE_ALG_GMAC, rctx->encrypt) |
-			      SE_AES_KEY_INDEX(ctx->key_id);
+			      SE_AES_KEY_INDEX(rctx->key_id);
 
 	cmdlen = tegra_gmac_prep_cmd(ctx, rctx);
 
···
 
 	rctx->config = tegra234_aes_cfg(SE_ALG_GCM, rctx->encrypt);
 	rctx->crypto_config = tegra234_aes_crypto_cfg(SE_ALG_GCM, rctx->encrypt) |
-			      SE_AES_KEY_INDEX(ctx->key_id);
+			      SE_AES_KEY_INDEX(rctx->key_id);
 
 	/* Prepare command and submit */
 	cmdlen = tegra_gcm_crypt_prep_cmd(ctx, rctx);
···
 
 	rctx->config = tegra234_aes_cfg(SE_ALG_GCM_FINAL, rctx->encrypt);
 	rctx->crypto_config = tegra234_aes_crypto_cfg(SE_ALG_GCM_FINAL, rctx->encrypt) |
-			      SE_AES_KEY_INDEX(ctx->key_id);
+			      SE_AES_KEY_INDEX(rctx->key_id);
 
 	/* Prepare command and submit */
 	cmdlen = tegra_gcm_prep_final_cmd(se, cpuvaddr, rctx);
···
 	rctx->config = tegra234_aes_cfg(SE_ALG_CBC_MAC, rctx->encrypt);
 	rctx->crypto_config = tegra234_aes_crypto_cfg(SE_ALG_CBC_MAC,
 						      rctx->encrypt) |
-						      SE_AES_KEY_INDEX(ctx->key_id);
+						      SE_AES_KEY_INDEX(rctx->key_id);
 
 	/* Prepare command and submit */
 	cmdlen = tegra_cbcmac_prep_cmd(ctx, rctx);
···
 
 	rctx->config = tegra234_aes_cfg(SE_ALG_CTR, rctx->encrypt);
 	rctx->crypto_config = tegra234_aes_crypto_cfg(SE_ALG_CTR, rctx->encrypt) |
-			      SE_AES_KEY_INDEX(ctx->key_id);
+			      SE_AES_KEY_INDEX(rctx->key_id);
 
 	/* Copy authdata in the top of buffer for encryption/decryption */
 	if (rctx->encrypt)
···
 	if (ret)
 		goto out_finalize;
 
+	rctx->key_id = ctx->key_id;
+
 	/* Allocate buffers required */
 	rctx->inbuf.size = rctx->assoclen + rctx->authsize + rctx->cryptlen + 100;
 	rctx->inbuf.buf = dma_alloc_coherent(ctx->se->dev, rctx->inbuf.size,
···
 	if (!rctx->outbuf.buf) {
 		ret = -ENOMEM;
 		goto out_free_inbuf;
+	}
+
+	if (!ctx->key_id) {
+		ret = tegra_key_submit_reserved_aes(ctx->se, ctx->key,
+						    ctx->keylen, ctx->alg, &rctx->key_id);
+		if (ret)
+			goto out;
 	}
 
 	if (rctx->encrypt) {
···
 	dma_free_coherent(ctx->se->dev, rctx->outbuf.size,
 			  rctx->inbuf.buf, rctx->inbuf.addr);
 
+	if (tegra_key_is_reserved(rctx->key_id))
+		tegra_key_invalidate_reserved(ctx->se, rctx->key_id, ctx->alg);
+
 out_finalize:
 	crypto_finalize_aead_request(ctx->se->engine, req, ret);
 
···
 	memcpy(rctx->iv, req->iv, GCM_AES_IV_SIZE);
 	rctx->iv[3] = (1 << 24);
 
+	rctx->key_id = ctx->key_id;
+
 	/* Allocate buffers required */
 	rctx->inbuf.size = rctx->assoclen + rctx->authsize + rctx->cryptlen;
 	rctx->inbuf.buf = dma_alloc_coherent(ctx->se->dev, rctx->inbuf.size,
···
 	if (!rctx->outbuf.buf) {
 		ret = -ENOMEM;
 		goto out_free_inbuf;
+	}
+
+	if (!ctx->key_id) {
+		ret = tegra_key_submit_reserved_aes(ctx->se, ctx->key,
+						    ctx->keylen, ctx->alg, &rctx->key_id);
+		if (ret)
+			goto out;
 	}
 
 	/* If there is associated data perform GMAC operation */
···
 	dma_free_coherent(ctx->se->dev, rctx->inbuf.size,
 			  rctx->inbuf.buf, rctx->inbuf.addr);
 
+	if (tegra_key_is_reserved(rctx->key_id))
+		tegra_key_invalidate_reserved(ctx->se, rctx->key_id, ctx->alg);
+
 out_finalize:
 	crypto_finalize_aead_request(ctx->se->engine, req, ret);
 
···
 
 	ctx->se = se_alg->se_dev;
 	ctx->key_id = 0;
+	ctx->keylen = 0;
 
 	ret = se_algname_to_algid(algname);
 	if (ret < 0) {
···
 			     const u8 *key, u32 keylen)
 {
 	struct tegra_aead_ctx *ctx = crypto_aead_ctx(tfm);
+	int ret;
 
 	if (aes_check_keylen(keylen)) {
 		dev_dbg(ctx->se->dev, "invalid key length (%d)\n", keylen);
 		return -EINVAL;
 	}
 
-	return tegra_key_submit(ctx->se, key, keylen, ctx->alg, &ctx->key_id);
+	ret = tegra_key_submit(ctx->se, key, keylen, ctx->alg, &ctx->key_id);
+	if (ret) {
+		ctx->keylen = keylen;
+		memcpy(ctx->key, key, keylen);
+	}
+
+	return 0;
 }
 
 static unsigned int tegra_cmac_prep_cmd(struct tegra_cmac_ctx *ctx,
···
 	rctx->total_len = 0;
 	rctx->datbuf.size = 0;
 	rctx->residue.size = 0;
+	rctx->key_id = ctx->key_id;
 	rctx->task |= SHA_FIRST;
 	rctx->blk_size = crypto_ahash_blocksize(tfm);
 
···
 	rctx->datbuf.size = (req->nbytes + rctx->residue.size) - nresidue;
 	rctx->total_len += rctx->datbuf.size;
 	rctx->config = tegra234_aes_cfg(SE_ALG_CMAC, 0);
-	rctx->crypto_config = SE_AES_KEY_INDEX(ctx->key_id);
+	rctx->crypto_config = SE_AES_KEY_INDEX(rctx->key_id);
 
 	/*
 	 * Keep one block and residue bytes in residue and
···
 		rctx->task &= ~SHA_INIT;
 	}
 
+	if (!ctx->key_id) {
+		ret = tegra_key_submit_reserved_aes(ctx->se, ctx->key,
+						    ctx->keylen, ctx->alg, &rctx->key_id);
+		if (ret)
+			goto out;
+	}
+
 	if (rctx->task & SHA_UPDATE) {
 		ret = tegra_cmac_do_update(req);
 		if (ret)
···
 		rctx->task &= ~SHA_FINAL;
 	}
 out:
+	if (tegra_key_is_reserved(rctx->key_id))
+		tegra_key_invalidate_reserved(ctx->se, rctx->key_id, ctx->alg);
+
 	crypto_finalize_hash_request(se->engine, req, ret);
 
 	return 0;
···
 
 	ctx->se = se_alg->se_dev;
 	ctx->key_id = 0;
+	ctx->keylen = 0;
 
 	ret = se_algname_to_algid(algname);
 	if (ret < 0) {
···
 			     unsigned int keylen)
 {
 	struct tegra_cmac_ctx *ctx = crypto_ahash_ctx(tfm);
+	int ret;
 
 	if (aes_check_keylen(keylen)) {
 		dev_dbg(ctx->se->dev, "invalid key length (%d)\n", keylen);
···
 	if (ctx->fallback_tfm)
 		crypto_shash_setkey(ctx->fallback_tfm, key, keylen);
 
-	return tegra_key_submit(ctx->se, key, keylen, ctx->alg, &ctx->key_id);
+	ret = tegra_key_submit(ctx->se, key, keylen, ctx->alg, &ctx->key_id);
+	if (ret) {
+		ctx->keylen = keylen;
+		memcpy(ctx->key, key, keylen);
+	}
+
+	return 0;
 }
 
 static int tegra_cmac_init(struct ahash_request *req)

drivers/crypto/tegra/tegra-se-key.c

···
 	tegra_keyslot_free(keyid);
 }
 
+void tegra_key_invalidate_reserved(struct tegra_se *se, u32 keyid, u32 alg)
+{
+	u8 zkey[AES_MAX_KEY_SIZE] = {0};
+
+	if (!keyid)
+		return;
+
+	/* Overwrite the key with 0s */
+	tegra_key_insert(se, zkey, AES_MAX_KEY_SIZE, keyid, alg);
+}
+
+inline int tegra_key_submit_reserved(struct tegra_se *se, const u8 *key,
+				     u32 keylen, u32 alg, u32 *keyid)
+{
+	return tegra_key_insert(se, key, keylen, *keyid, alg);
+}
+
 int tegra_key_submit(struct tegra_se *se, const u8 *key, u32 keylen, u32 alg, u32 *keyid)
 {
 	int ret;
···
 	if (!tegra_key_in_kslt(*keyid)) {
 		*keyid = tegra_keyslot_alloc();
 		if (!(*keyid)) {
-			dev_err(se->dev, "failed to allocate key slot\n");
+			dev_dbg(se->dev, "failed to allocate key slot\n");
 			return -ENOMEM;
 		}
 	}

drivers/crypto/tegra/tegra-se.h

···
 #define SE_MAX_KEYSLOT				15
 #define SE_MAX_MEM_ALLOC			SZ_4M
 
+#define TEGRA_AES_RESERVED_KSLT			14
+#define TEGRA_XTS_RESERVED_KSLT			15
+
 #define SHA_FIRST	BIT(0)
 #define SHA_INIT	BIT(1)
 #define SHA_UPDATE	BIT(2)
···
 void tegra_deinit_hash(struct tegra_se *se);
 int tegra_key_submit(struct tegra_se *se, const u8 *key,
 		     u32 keylen, u32 alg, u32 *keyid);
+
+int tegra_key_submit_reserved(struct tegra_se *se, const u8 *key,
+			      u32 keylen, u32 alg, u32 *keyid);
+
 void tegra_key_invalidate(struct tegra_se *se, u32 keyid, u32 alg);
+void tegra_key_invalidate_reserved(struct tegra_se *se, u32 keyid, u32 alg);
 int tegra_se_host1x_submit(struct tegra_se *se, struct tegra_se_cmdbuf *cmdbuf, u32 size);
+
+static inline int tegra_key_submit_reserved_aes(struct tegra_se *se, const u8 *key,
+						u32 keylen, u32 alg, u32 *keyid)
+{
+	*keyid = TEGRA_AES_RESERVED_KSLT;
+	return tegra_key_submit_reserved(se, key, keylen, alg, keyid);
+}
+
+static inline int tegra_key_submit_reserved_xts(struct tegra_se *se, const u8 *key,
+						u32 keylen, u32 alg, u32 *keyid)
+{
+	*keyid = TEGRA_XTS_RESERVED_KSLT;
+	return tegra_key_submit_reserved(se, key, keylen, alg, keyid);
+}
+
+static inline bool tegra_key_is_reserved(u32 keyid)
+{
+	return ((keyid == TEGRA_AES_RESERVED_KSLT) ||
+		(keyid == TEGRA_XTS_RESERVED_KSLT));
+}
 
 /* HOST1x OPCODES */
 static inline u32 host1x_opcode_setpayload(unsigned int payload)