[dpdk-dev] [PATCH v2] examples/vhost_crypto: fix zero copy

[Fan Zhang <roy.fan.zhang@intel.com>]

This patch fixes the zero copy enable problem for vhost crypto
sample application.

For some Crypto PMDs such as AESNI-MB and AESNI-GCM the data to
be processed will be made a copy in the same buffer but next to the
data. For example, to encrypt 64 bytes data the PMD will copy this
data from offset 64 to offset 123. This requires the application
provides the buffer with at least double of the data size.

However there is no way for VMs to know this limitation. When
zero-copy is enabled in Vhost the PMD may overwrite the buffer
next to the VM data to be processed, and further cause problems
such as Segmentation Fault or even worse, crashes the VM.

To fix the problem the user should avoid enabling the zero copy
for these Crypto PMDs. This patch adds the checking of the PMD
names to see if zero copy can be applied.

Fixes: 709521f4c2cd ("examples/vhost_crypto: support multi-core")

Signed-off-by: Fan Zhang <roy.fan.zhang@intel.com>
---
v2:
- removed unecessary checks
- Changed log message when zero-copy is not applicable.

 examples/vhost_crypto/main.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/examples/vhost_crypto/main.c b/examples/vhost_crypto/main.c
index cbb5e49d2..f08babd97 100644
--- a/examples/vhost_crypto/main.c
+++ b/examples/vhost_crypto/main.c
@@ -4,6 +4,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <stdbool.h>
 #include <assert.h>
@@ -442,6 +443,9 @@ free_resource(void)
 		struct lcore_option *lo = &options.los[i];
 		struct vhost_crypto_info *info = options.infos[i];
 
+		if (!info)
+			continue;
+
 		rte_mempool_free(info->cop_pool);
 		rte_mempool_free(info->sess_pool);
 
@@ -493,6 +497,19 @@ main(int argc, char *argv[])
 		info->nb_vids = lo->nb_sockets;
 
 		rte_cryptodev_info_get(info->cid, &dev_info);
+		if (options.zero_copy == RTE_VHOST_CRYPTO_ZERO_COPY_ENABLE) {
+#define VHOST_CRYPTO_CDEV_NAME_AESNI_MB_PMD	crypto_aesni_mb
+#define VHOST_CRYPTO_CDEV_NAME_AESNI_GCM_PMD	crypto_aesni_gcm
+			if (strstr(dev_info.driver_name,
+				RTE_STR(VHOST_CRYPTO_CDEV_NAME_AESNI_MB_PMD)) ||
+				strstr(dev_info.driver_name,
+				RTE_STR(VHOST_CRYPTO_CDEV_NAME_AESNI_GCM_PMD)))
+			RTE_LOG(ERR, USER1, "Cannot enable zero-copy in %s\n",
+					dev_info.driver_name);
+			ret = -EPERM;
+			goto error_exit;
+		}
+
 		if (dev_info.max_nb_queue_pairs < info->qid + 1) {
 			RTE_LOG(ERR, USER1, "Number of queues cannot over %u",
 					dev_info.max_nb_queue_pairs);
-- 
2.13.6