[PATCH v2 2/2] hw/misc/aspeed_hace: Fix SG Accumulative hashing

[Alejandro Zeise]

Make the Aspeed HACE module use the new qcrypto accumulative hashing functions
when in scatter-gather accumulative mode. A hash context will maintain a
"running-hash" as each scatter-gather chunk is received.

Previously each scatter-gather "chunk" was cached
so the hash could be computed once the final chunk was received.
However, the cache was a shallow copy, so once the guest overwrote the
memory provided to HACE the final hash would not be correct.

Possibly related to: https://gitlab.com/qemu-project/qemu/-/issues/1121
Buglink: https://github.com/openbmc/qemu/issues/36

Signed-off-by: Alejandro Zeise <alejandro.zeise@seagate.com>
---
 hw/misc/aspeed_hace.c         | 91 ++++++++++++++++++-----------------
 include/hw/misc/aspeed_hace.h |  4 ++
 2 files changed, 51 insertions(+), 44 deletions(-)

diff --git a/hw/misc/aspeed_hace.c b/hw/misc/aspeed_hace.c
index c06c04ddc6..8306d8986a 100644
--- a/hw/misc/aspeed_hace.c
+++ b/hw/misc/aspeed_hace.c
@@ -1,6 +1,7 @@
 /*
  * ASPEED Hash and Crypto Engine
  *
+ * Copyright (c) 2024 Seagate Technology LLC and/or its Affiliates
  * Copyright (C) 2021 IBM Corp.
  *
  * Joel Stanley <joel@jms.id.au>
@@ -151,47 +152,15 @@ static int reconstruct_iov(AspeedHACEState *s, struct 
iovec *iov, int id,
     return iov_count;
 }
 
-/**
- * Generate iov for accumulative mode.
- *
- * @param s             aspeed hace state object
- * @param iov           iov of the current request
- * @param id            index of the current iov
- * @param req_len       length of the current request
- *
- * @return count of iov
- */
-static int gen_acc_mode_iov(AspeedHACEState *s, struct iovec *iov, int id,
-                            hwaddr *req_len)
-{
-    uint32_t pad_offset;
-    uint32_t total_msg_len;
-    s->total_req_len += *req_len;
-
-    if (has_padding(s, &iov[id], *req_len, &total_msg_len, &pad_offset)) {
-        if (s->iov_count) {
-            return reconstruct_iov(s, iov, id, &pad_offset);
-        }
-
-        *req_len -= s->total_req_len - total_msg_len;
-        s->total_req_len = 0;
-        iov[id].iov_len = *req_len;
-    } else {
-        s->iov_cache[s->iov_count].iov_base = iov->iov_base;
-        s->iov_cache[s->iov_count].iov_len = *req_len;
-        ++s->iov_count;
-    }
-
-    return id + 1;
-}
-
 static void do_hash_operation(AspeedHACEState *s, int algo, bool sg_mode,
                               bool acc_mode)
 {
     struct iovec iov[ASPEED_HACE_MAX_SG];
+    uint32_t total_msg_len;
+    uint32_t pad_offset;
     g_autofree uint8_t *digest_buf = NULL;
     size_t digest_len = 0;
-    int niov = 0;
+    bool sg_acc_mode_final_request = false;
     int i;
     void *haddr;
 
@@ -226,8 +195,15 @@ static void do_hash_operation(AspeedHACEState *s, int 
algo, bool sg_mode,
             }
             iov[i].iov_base = haddr;
             if (acc_mode) {
-                niov = gen_acc_mode_iov(s, iov, i, &plen);
-
+                s->total_req_len += plen;
+
+                if (has_padding(s, &iov[i], plen, &total_msg_len, 
&pad_offset)) {
+                    /* Padding being present indicates the final request */
+                    sg_acc_mode_final_request = true;
+                    iov[i].iov_len = pad_offset;
+                } else {
+                    iov[i].iov_len = plen;
+                }
             } else {
                 iov[i].iov_len = plen;
             }
@@ -252,20 +228,42 @@ static void do_hash_operation(AspeedHACEState *s, int 
algo, bool sg_mode,
              * required to check whether cache is empty. If no, we should
              * combine cached iov and the current iov.
              */
-            uint32_t total_msg_len;
-            uint32_t pad_offset;
             s->total_req_len += len;
             if (has_padding(s, iov, len, &total_msg_len, &pad_offset)) {
-                niov = reconstruct_iov(s, iov, 0, &pad_offset);
+                i = reconstruct_iov(s, iov, 0, &pad_offset);
             }
         }
     }
 
-    if (niov) {
-        i = niov;
-    }
+    if (acc_mode) {
+        if (s->qcrypto_hash_context == NULL &&
+            qcrypto_hash_accumulate_new_ctx(algo, &s->qcrypto_hash_context, 
NULL)) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: qcrypto failed to create hash context\n",
+                          __func__);
+            return;
+        }
+
+        if (qcrypto_hash_accumulate_bytesv(algo,
+                                           s->qcrypto_hash_context, iov, i,
+                                           &digest_buf,
+                                           &digest_len, NULL) < 0) {
+
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: qcrypto failed\n", __func__);
+            return;
+        }
 
-    if (qcrypto_hash_bytesv(algo, iov, i, &digest_buf, &digest_len, NULL) < 0) 
{
+        if (sg_acc_mode_final_request) {
+            if (qcrypto_hash_accumulate_free_ctx(s->qcrypto_hash_context, 
NULL) < 0) {
+                qemu_log_mask(LOG_GUEST_ERROR,
+                              "%s: qcrypto failed to free context\n", 
__func__);
+            }
+
+            s->qcrypto_hash_context = NULL;
+            s->iov_count = 0;
+            s->total_req_len = 0;
+        }
+    } else if (qcrypto_hash_bytesv(algo, iov, i, &digest_buf, &digest_len, 
NULL) < 0) {
         qemu_log_mask(LOG_GUEST_ERROR, "%s: qcrypto failed\n", __func__);
         return;
     }
@@ -397,6 +395,11 @@ static void aspeed_hace_reset(DeviceState *dev)
 {
     struct AspeedHACEState *s = ASPEED_HACE(dev);
 
+    if (s->qcrypto_hash_context != NULL) {
+        qcrypto_hash_accumulate_free_ctx(s->qcrypto_hash_context, NULL);
+        s->qcrypto_hash_context = NULL;
+    }
+
     memset(s->regs, 0, sizeof(s->regs));
     s->iov_count = 0;
     s->total_req_len = 0;
diff --git a/include/hw/misc/aspeed_hace.h b/include/hw/misc/aspeed_hace.h
index ecb1b67de8..b3c2eb17b7 100644
--- a/include/hw/misc/aspeed_hace.h
+++ b/include/hw/misc/aspeed_hace.h
@@ -1,6 +1,7 @@
 /*
  * ASPEED Hash and Crypto Engine
  *
+ * Copyright (c) 2024 Seagate Technology LLC and/or its Affiliates
  * Copyright (C) 2021 IBM Corp.
  *
  * SPDX-License-Identifier: GPL-2.0-or-later
@@ -10,6 +11,7 @@
 #define ASPEED_HACE_H
 
 #include "hw/sysbus.h"
+#include "crypto/hash.h"
 
 #define TYPE_ASPEED_HACE "aspeed.hace"
 #define TYPE_ASPEED_AST2400_HACE TYPE_ASPEED_HACE "-ast2400"
@@ -35,6 +37,8 @@ struct AspeedHACEState {
 
     MemoryRegion *dram_mr;
     AddressSpace dram_as;
+
+    qcrypto_hash_accumulate_ctx_t *qcrypto_hash_context;
 };
 
 
-- 
2.34.1