[Qemu-devel] [RFC v1 1/1] virtio-crypto: Allow disabling of cipher algorithms for virtio-crypto device

[Farhan Ali <alifm@linux.ibm.com>]

The virtio-crypto driver currently propagates to the guest
all the cipher algorithms that the backend cryptodev can
support. But in certain cases where the guest has more
performant mechanism to handle some algorithms, it would be
useful to propagate only a subset of the algorithms.

This patch adds support for disabling the cipher
algorithms of the backend cryptodev.

eg:
 -object cryptodev-backend-builtin,id=cryptodev0
 -device virtio-crypto-ccw,id=crypto0,cryptodev=cryptodev0,cipher-aes-cbc=off

Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
---

Please note this patch is not complete, and there are TODOs to handle
for other types of algorithms such Hash, AEAD and MAC algorithms.

This is mainly intended to get some feedback on the design approach
from the community.


 hw/virtio/virtio-crypto.c         | 46 ++++++++++++++++++++++++++++++++++++---
 include/hw/virtio/virtio-crypto.h |  3 +++
 2 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/hw/virtio/virtio-crypto.c b/hw/virtio/virtio-crypto.c
index 9a9fa49..4aed9ca 100644
--- a/hw/virtio/virtio-crypto.c
+++ b/hw/virtio/virtio-crypto.c
@@ -754,12 +754,22 @@ static void virtio_crypto_reset(VirtIODevice *vdev)
 static void virtio_crypto_init_config(VirtIODevice *vdev)
 {
     VirtIOCrypto *vcrypto = VIRTIO_CRYPTO(vdev);
+    uint32_t user_crypto_services = (1u << VIRTIO_CRYPTO_SERVICE_CIPHER) |
+                                    (1u << VIRTIO_CRYPTO_SERVICE_HASH) |
+                                    (1u << VIRTIO_CRYPTO_SERVICE_AEAD) |
+                                    (1u << VIRTIO_CRYPTO_SERVICE_MAC);
+
+    if (vcrypto->user_cipher_algo_l & (1u << VIRTIO_CRYPTO_NO_CIPHER)) {
+        vcrypto->user_cipher_algo_l = 1u << VIRTIO_CRYPTO_NO_CIPHER;
+        vcrypto->user_cipher_algo_h = 0;
+        user_crypto_services &= ~(1u << VIRTIO_CRYPTO_SERVICE_CIPHER);
+    }
 
-    vcrypto->conf.crypto_services =
+    vcrypto->conf.crypto_services = user_crypto_services &
                      vcrypto->conf.cryptodev->conf.crypto_services;
-    vcrypto->conf.cipher_algo_l =
+    vcrypto->conf.cipher_algo_l = vcrypto->user_cipher_algo_l &
                      vcrypto->conf.cryptodev->conf.cipher_algo_l;
-    vcrypto->conf.cipher_algo_h =
+    vcrypto->conf.cipher_algo_h = vcrypto->user_cipher_algo_h &
                      vcrypto->conf.cryptodev->conf.cipher_algo_h;
     vcrypto->conf.hash_algo = vcrypto->conf.cryptodev->conf.hash_algo;
     vcrypto->conf.mac_algo_l = vcrypto->conf.cryptodev->conf.mac_algo_l;
@@ -853,6 +863,34 @@ static const VMStateDescription vmstate_virtio_crypto = {
 static Property virtio_crypto_properties[] = {
     DEFINE_PROP_LINK("cryptodev", VirtIOCrypto, conf.cryptodev,
                      TYPE_CRYPTODEV_BACKEND, CryptoDevBackend *),
+    DEFINE_PROP_BIT("no-cipher", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_ARC4, false),
+    DEFINE_PROP_BIT("cipher-arc4", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_ARC4, false),
+    DEFINE_PROP_BIT("cipher-aes-ecb", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_AES_ECB, false),
+    DEFINE_PROP_BIT("cipher-aes-cbc", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_AES_CBC, false),
+    DEFINE_PROP_BIT("cipher-aes-ctr", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_AES_CTR, false),
+    DEFINE_PROP_BIT("cipher-des-ecb", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_DES_ECB, false),
+    DEFINE_PROP_BIT("cipher-3des-ecb", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_3DES_ECB, false),
+    DEFINE_PROP_BIT("cipher-3des-cbc", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_3DES_CBC, false),
+    DEFINE_PROP_BIT("cipher-3des-ctr", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_3DES_CTR, false),
+    DEFINE_PROP_BIT("cipher-kasumi-f8", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_KASUMI_F8, false),
+    DEFINE_PROP_BIT("cipher-snow3g-uea2", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_SNOW3G_UEA2, false),
+    DEFINE_PROP_BIT("cipher-aes-f8", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_AES_F8, false),
+    DEFINE_PROP_BIT("cipher-aes-xts", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_AES_XTS, false),
+    DEFINE_PROP_BIT("cipher-zuc-eea3", VirtIOCrypto, user_cipher_algo_l,
+                    VIRTIO_CRYPTO_CIPHER_ZUC_EEA3, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -974,6 +1012,8 @@ static void virtio_crypto_instance_init(Object *obj)
      * Can be overriden with virtio_crypto_set_config_size.
      */
     vcrypto->config_size = sizeof(struct virtio_crypto_config);
+    vcrypto->user_cipher_algo_l = ~VIRTIO_CRYPTO_NO_CIPHER - 1;
+    vcrypto->user_cipher_algo_h = ~VIRTIO_CRYPTO_NO_CIPHER;
 }
 
 static const TypeInfo virtio_crypto_info = {
diff --git a/include/hw/virtio/virtio-crypto.h b/include/hw/virtio/virtio-crypto.h
index ca3a049..c5bb684 100644
--- a/include/hw/virtio/virtio-crypto.h
+++ b/include/hw/virtio/virtio-crypto.h
@@ -97,6 +97,9 @@ typedef struct VirtIOCrypto {
     uint32_t curr_queues;
     size_t config_size;
     uint8_t vhost_started;
+
+    uint32_t user_cipher_algo_l;
+    uint32_t user_cipher_algo_h;
 } VirtIOCrypto;
 
 #endif /* _QEMU_VIRTIO_CRYPTO_H */
-- 
2.7.4