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From: Parav Pandit <parav@mellanox.com>
To: Jiri Pirko <jiri@resnulli.us>
Cc: "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Saeed Mahameed <saeedm@mellanox.com>,
	"kwankhede@nvidia.com" <kwankhede@nvidia.com>,
	"leon@kernel.org" <leon@kernel.org>,
	"cohuck@redhat.com" <cohuck@redhat.com>,
	Jiri Pirko <jiri@mellanox.com>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
Subject: RE: [PATCH net-next 07/19] vfio/mdev: Introduce sha1 based mdev alias
Date: Fri, 8 Nov 2019 15:59:53 +0000
Message-ID: <AM0PR05MB48667AF9F6EACF0CE1688262D17B0@AM0PR05MB4866.eurprd05.prod.outlook.com> (raw)
In-Reply-To: <20191108110456.GH6990@nanopsycho>



> -----Original Message-----
> From: Jiri Pirko <jiri@resnulli.us>
> Sent: Friday, November 8, 2019 5:05 AM
> To: Parav Pandit <parav@mellanox.com>
> Cc: alex.williamson@redhat.com; davem@davemloft.net;
> kvm@vger.kernel.org; netdev@vger.kernel.org; Saeed Mahameed
> <saeedm@mellanox.com>; kwankhede@nvidia.com; leon@kernel.org;
> cohuck@redhat.com; Jiri Pirko <jiri@mellanox.com>; linux-
> rdma@vger.kernel.org
> Subject: Re: [PATCH net-next 07/19] vfio/mdev: Introduce sha1 based mdev
> alias
> 
> Thu, Nov 07, 2019 at 05:08:22PM CET, parav@mellanox.com wrote:
> >Some vendor drivers want an identifier for an mdev device that is
> >shorter than the UUID, due to length restrictions in the consumers of
> >that identifier.
> >
> >Add a callback that allows a vendor driver to request an alias of a
> >specified length to be generated for an mdev device. If generated, that
> >alias is checked for collisions.
> >
> >It is an optional attribute.
> >mdev alias is generated using sha1 from the mdev name.
> >
> >Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
> >Signed-off-by: Parav Pandit <parav@mellanox.com>
> >---
> > drivers/vfio/mdev/mdev_core.c    | 123
> ++++++++++++++++++++++++++++++-
> > drivers/vfio/mdev/mdev_private.h |   5 +-
> > drivers/vfio/mdev/mdev_sysfs.c   |  13 ++--
> > include/linux/mdev.h             |   4 +
> > 4 files changed, 135 insertions(+), 10 deletions(-)
> >
> >diff --git a/drivers/vfio/mdev/mdev_core.c
> >b/drivers/vfio/mdev/mdev_core.c index b558d4cfd082..3bdff0469607
> 100644
> >--- a/drivers/vfio/mdev/mdev_core.c
> >+++ b/drivers/vfio/mdev/mdev_core.c
> >@@ -10,9 +10,11 @@
> 
> [...]
> 
> 
> >-int mdev_device_create(struct kobject *kobj,
> >-		       struct device *dev, const guid_t *uuid)
> >+static const char *
> >+generate_alias(const char *uuid, unsigned int max_alias_len) {
> >+	struct shash_desc *hash_desc;
> >+	unsigned int digest_size;
> >+	unsigned char *digest;
> >+	unsigned int alias_len;
> >+	char *alias;
> >+	int ret;
> >+
> >+	/*
> >+	 * Align to multiple of 2 as bin2hex will generate
> >+	 * even number of bytes.
> >+	 */
> >+	alias_len = roundup(max_alias_len, 2);
> 
> This is odd, see below.
> 
> 
> >+	alias = kzalloc(alias_len + 1, GFP_KERNEL);
> >+	if (!alias)
> >+		return ERR_PTR(-ENOMEM);
> >+
> >+	/* Allocate and init descriptor */
> >+	hash_desc = kvzalloc(sizeof(*hash_desc) +
> >+			     crypto_shash_descsize(alias_hash),
> >+			     GFP_KERNEL);
> >+	if (!hash_desc) {
> >+		ret = -ENOMEM;
> >+		goto desc_err;
> >+	}
> >+
> >+	hash_desc->tfm = alias_hash;
> >+
> >+	digest_size = crypto_shash_digestsize(alias_hash);
> >+
> >+	digest = kzalloc(digest_size, GFP_KERNEL);
> >+	if (!digest) {
> >+		ret = -ENOMEM;
> >+		goto digest_err;
> >+	}
> >+	ret = crypto_shash_init(hash_desc);
> >+	if (ret)
> >+		goto hash_err;
> >+
> >+	ret = crypto_shash_update(hash_desc, uuid, UUID_STRING_LEN);
> >+	if (ret)
> >+		goto hash_err;
> >+
> >+	ret = crypto_shash_final(hash_desc, digest);
> >+	if (ret)
> >+		goto hash_err;
> >+
> >+	bin2hex(alias, digest, min_t(unsigned int, digest_size, alias_len / 2));
> >+	/*
> >+	 * When alias length is odd, zero out an additional last byte
> >+	 * that bin2hex has copied.
> >+	 */
> >+	if (max_alias_len % 2)
> >+		alias[max_alias_len] = 0;
> >+
> >+	kfree(digest);
> >+	kvfree(hash_desc);
> >+	return alias;
> >+
> >+hash_err:
> >+	kfree(digest);
> >+digest_err:
> >+	kvfree(hash_desc);
> >+desc_err:
> >+	kfree(alias);
> >+	return ERR_PTR(ret);
> >+}
> >+
> >+int mdev_device_create(struct kobject *kobj, struct device *dev,
> >+		       const char *uuid_str, const guid_t *uuid)
> > {
> > 	int ret;
> > 	struct mdev_device *mdev, *tmp;
> > 	struct mdev_parent *parent;
> > 	struct mdev_type *type = to_mdev_type(kobj);
> >+	const char *alias = NULL;
> >
> > 	parent = mdev_get_parent(type->parent);
> > 	if (!parent)
> > 		return -EINVAL;
> >
> >+	if (parent->ops->get_alias_length) {
> >+		unsigned int alias_len;
> >+
> >+		alias_len = parent->ops->get_alias_length();
> >+		if (alias_len) {
> 
> I think this should be with WARN_ON. Driver should not never return such
> 0 and if it does, it's a bug.
>
Ok. will add it.
 
> Also I think this check should be extended by checking value is multiple of 2.
Do you mean driver must set alias length as always multiple of 2? Why?

> Then you can avoid the roundup() above. No need to allow even len.
Did you mean "no need to allow odd"? or? 
 
> 
> [...]
> 
> >diff --git a/drivers/vfio/mdev/mdev_sysfs.c
> >b/drivers/vfio/mdev/mdev_sysfs.c index 7570c7602ab4..43afe0e80b76
> >100644
> >--- a/drivers/vfio/mdev/mdev_sysfs.c
> >+++ b/drivers/vfio/mdev/mdev_sysfs.c
> >@@ -63,15 +63,18 @@ static ssize_t create_store(struct kobject *kobj,
> struct device *dev,
> > 		return -ENOMEM;
> >
> > 	ret = guid_parse(str, &uuid);
> >-	kfree(str);
> > 	if (ret)
> >-		return ret;
> >+		goto err;
> >
> >-	ret = mdev_device_create(kobj, dev, &uuid);
> >+	ret = mdev_device_create(kobj, dev, str, &uuid);
> 
> Why to pass the same thing twice? Move the guid_parse() call to the
> beginning of mdev_device_create() function.
>
Because alias should be unique and need to hold the lock while searching for duplicate.
So it is not done twice, and moving guid_parse() won't help due to need of lock.
 
> 
> > 	if (ret)
> >-		return ret;
> >+		goto err;
> >
> >-	return count;
> >+	ret = count;
> >+
> >+err:
> >+	kfree(str);
> >+	return ret;
> > }
> >
> > MDEV_TYPE_ATTR_WO(create);
> 
> [...]

  reply index

Thread overview: 132+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-07 16:04 [PATCH net-next 00/19] Mellanox, mlx5 sub function support Parav Pandit
2019-11-07 16:08 ` [PATCH net-next 01/19] net/mlx5: E-switch, Move devlink port close to eswitch port Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 02/19] net/mlx5: E-Switch, Add SF vport, vport-rep support Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 03/19] net/mlx5: Introduce SF table framework Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 04/19] net/mlx5: Introduce SF life cycle APIs to allocate/free Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 05/19] net/mlx5: E-Switch, Enable/disable SF's vport during SF life cycle Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 06/19] net/mlx5: Add support for mediated devices in switchdev mode Parav Pandit
2019-11-08 10:32     ` Jiri Pirko
2019-11-08 16:03       ` Parav Pandit
2019-11-08 16:22         ` Jiri Pirko
2019-11-08 16:29           ` Parav Pandit
2019-11-08 18:01             ` Jiri Pirko
2019-11-08 18:04             ` Jiri Pirko
2019-11-08 18:21               ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 07/19] vfio/mdev: Introduce sha1 based mdev alias Parav Pandit
2019-11-08 11:04     ` Jiri Pirko
2019-11-08 15:59       ` Parav Pandit [this message]
2019-11-08 16:28         ` Jiri Pirko
2019-11-08 11:10     ` Cornelia Huck
2019-11-08 16:03       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 08/19] vfio/mdev: Make mdev alias unique among all mdevs Parav Pandit
2019-11-08 10:49     ` Jiri Pirko
2019-11-08 15:13       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 09/19] vfio/mdev: Expose mdev alias in sysfs tree Parav Pandit
2019-11-08 13:22     ` Jiri Pirko
2019-11-08 18:03       ` Alex Williamson
2019-11-08 18:16         ` Jiri Pirko
2019-11-07 16:08   ` [PATCH net-next 10/19] vfio/mdev: Introduce an API mdev_alias Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 11/19] vfio/mdev: Improvise mdev life cycle and parent removal scheme Parav Pandit
2019-11-08 13:01     ` Cornelia Huck
2019-11-08 16:12       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 12/19] devlink: Introduce mdev port flavour Parav Pandit
2019-11-07 20:38     ` Jakub Kicinski
2019-11-07 21:03       ` Parav Pandit
2019-11-08  1:17         ` Jakub Kicinski
2019-11-08  1:44           ` Parav Pandit
2019-11-08  2:20             ` Jakub Kicinski
2019-11-08  2:31               ` Parav Pandit
2019-11-08  9:46                 ` Jiri Pirko
2019-11-08 15:45                   ` Parav Pandit
2019-11-08 16:31                     ` Jiri Pirko
2019-11-08 16:43                       ` Parav Pandit
2019-11-08 18:11                         ` Jiri Pirko
2019-11-08 18:23                           ` Parav Pandit
2019-11-08 18:34                             ` Jiri Pirko
2019-11-08 18:56                               ` Parav Pandit
2019-11-08  9:30               ` Jiri Pirko
2019-11-08 15:41                 ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 13/19] net/mlx5: Register SF devlink port Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 14/19] net/mlx5: Share irqs between SFs and parent PCI device Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 15/19] net/mlx5: Add load/unload routines for SF driver binding Parav Pandit
2019-11-08  9:48     ` Jiri Pirko
2019-11-08 11:13       ` Jiri Pirko
2019-11-07 16:08   ` [PATCH net-next 16/19] net/mlx5: Implement dma ops and params for mediated device Parav Pandit
2019-11-07 20:42     ` Jakub Kicinski
2019-11-07 21:30       ` Parav Pandit
2019-11-08  1:16         ` Jakub Kicinski
2019-11-08  6:37     ` Christoph Hellwig
2019-11-08 15:29       ` Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 17/19] net/mlx5: Add mdev driver to bind to mdev devices Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 18/19] Documentation: net: mlx5: Add mdev usage documentation Parav Pandit
2019-11-07 16:08   ` [PATCH net-next 19/19] mtty: Optionally support mtty alias Parav Pandit
2019-11-08  6:26     ` Leon Romanovsky
2019-11-08 10:45     ` Jiri Pirko
2019-11-08 15:08       ` Parav Pandit
2019-11-08 15:15         ` Jiri Pirko
2019-11-08 13:46     ` Cornelia Huck
2019-11-08 15:10       ` Parav Pandit
2019-11-08 15:28         ` Cornelia Huck
2019-11-08 15:30           ` Parav Pandit
2019-11-08 17:54             ` Alex Williamson
2019-11-08  9:51   ` [PATCH net-next 01/19] net/mlx5: E-switch, Move devlink port close to eswitch port Jiri Pirko
2019-11-08 15:50     ` Parav Pandit
2019-11-07 17:03 ` [PATCH net-next 00/19] Mellanox, mlx5 sub function support Leon Romanovsky
2019-11-07 20:10   ` Parav Pandit
2019-11-08  6:20     ` Leon Romanovsky
2019-11-08 15:01       ` Parav Pandit
2019-11-07 20:32 ` Jakub Kicinski
2019-11-07 20:52   ` Parav Pandit
2019-11-08  1:16     ` Jakub Kicinski
2019-11-08  1:49       ` Parav Pandit
2019-11-08  2:12         ` Jakub Kicinski
2019-11-08 12:12   ` Jiri Pirko
2019-11-08 14:40     ` Jason Gunthorpe
2019-11-08 15:40       ` Parav Pandit
2019-11-08 19:12         ` Jakub Kicinski
2019-11-08 20:12           ` Jason Gunthorpe
2019-11-08 20:20             ` Parav Pandit
2019-11-08 20:32               ` Jason Gunthorpe
2019-11-08 20:52                 ` gregkh
2019-11-08 20:34             ` Alex Williamson
2019-11-08 21:05               ` Jason Gunthorpe
2019-11-08 21:19                 ` gregkh
2019-11-08 21:52                 ` Alex Williamson
2019-11-08 22:48                   ` Parav Pandit
2019-11-09  0:57                     ` Jason Gunthorpe
2019-11-09 17:41                       ` Jakub Kicinski
2019-11-10 19:04                         ` Jason Gunthorpe
2019-11-10 19:48                       ` Parav Pandit
2019-11-11 14:17                         ` Jiri Pirko
2019-11-11 14:58                           ` Parav Pandit
2019-11-11 15:06                             ` Jiri Pirko
2019-11-19  4:51                               ` Parav Pandit
2019-11-09  0:12                   ` Jason Gunthorpe
2019-11-09  0:45                     ` Parav Pandit
2019-11-11  2:19                 ` Jason Wang
2019-11-08 21:45             ` Jakub Kicinski
2019-11-09  0:44               ` Jason Gunthorpe
2019-11-09  8:46                 ` gregkh
2019-11-09 11:18                   ` Jiri Pirko
2019-11-09 17:28                     ` Jakub Kicinski
2019-11-10  9:16                     ` gregkh
2019-11-09 17:27                 ` Jakub Kicinski
2019-11-10  9:18                   ` gregkh
2019-11-11  3:46                     ` Jakub Kicinski
2019-11-11  5:18                       ` Parav Pandit
2019-11-11 13:30                       ` Jiri Pirko
2019-11-11 14:14                         ` gregkh
2019-11-11 14:37                           ` Jiri Pirko
2019-11-10 19:37                   ` Jason Gunthorpe
2019-11-11  3:57                     ` Jakub Kicinski
2019-11-08 16:06     ` Parav Pandit
2019-11-08 19:06     ` Jakub Kicinski
2019-11-08 19:34       ` Parav Pandit
2019-11-08 19:48         ` Jakub Kicinski
2019-11-08 19:41       ` Jiri Pirko
2019-11-08 20:40         ` Parav Pandit
2019-11-08 21:21         ` Jakub Kicinski
2019-11-08 21:39           ` Jiri Pirko
2019-11-08 21:51             ` Jakub Kicinski
2019-11-08 22:21               ` Jiri Pirko
2019-11-07 23:57 ` David Miller

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