[PULL 06/20] hw/misc/max78000_aes: Comment Internal Key Storage

Maintainers: Cameron Esfahani <dirty@apple.com>, Roman Bolshakov <rbolshakov@ddn.com>, Phil Dennis-Jordan <phil@philjordan.eu>, Mads Ynddal <mads@ynddal.dk>, "Cédric Le Goater" <clg@kaod.org>, Peter Maydell <peter.maydell@linaro.org>, Steven Lee <steven_lee@aspeedtech.com>, Troy Lee <leetroy@gmail.com>, Jamin Lin <jamin_lin@aspeedtech.com>, Andrew Jeffery <andrew@codeconstruct.com.au>, Joel Stanley <joel@jms.id.au>, Alexander Graf <agraf@csgraf.de>, Paolo Bonzini <pbonzini@redhat.com>
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[PULL 06/20] hw/misc/max78000_aes: Comment Internal Key Storage
Posted by Peter Maydell 3 months, 3 weeks ago
From: Jackson Donaldson <jackson88044@gmail.com>

Coverity Scan noted an unusual pattern in the
MAX78000 aes device, with duplicated calls to
set_decrypt. This commit adds a comment noting
why the implementation is correct.

Signed-off-by: Jackson Donaldson <jcksn@duck.com>
Message-id: 20250716002622.84685-1-jcksn@duck.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/misc/max78000_aes.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/misc/max78000_aes.c b/hw/misc/max78000_aes.c
index 0bfb2f02b5b..d883ddd2b61 100644
--- a/hw/misc/max78000_aes.c
+++ b/hw/misc/max78000_aes.c
@@ -79,6 +79,12 @@ static void max78000_aes_do_crypto(Max78000AesState *s)
         keydata += 8;
     }
 
+    /*
+     * The MAX78000 AES engine stores an internal key, which it uses only
+     * for decryption. This results in the slighly odd looking pairs of
+     * set_encrypt and set_decrypt calls below; s->internal_key is
+     * being stored for later use in both cases.
+     */
     AES_KEY key;
     if ((s->ctrl & TYPE) == 0) {
         AES_set_encrypt_key(keydata, keylen, &key);
-- 
2.43.0