On Mon, 26 Aug 2019 19:44:56 -0600 Alex Williamson <[email protected]> wrote:
> On Mon, 26 Aug 2019 15:41:16 -0500 > Parav Pandit <[email protected]> wrote: > > > Whenever a parent requests to generate mdev alias, generate a mdev > > alias. > > It is an optional attribute that parent can request to generate > > for each of its child mdev. > > mdev alias is generated using sha1 from the mdev name. > > > > Signed-off-by: Parav Pandit <[email protected]> > > --- > > drivers/vfio/mdev/mdev_core.c | 98 +++++++++++++++++++++++++++++++- > > drivers/vfio/mdev/mdev_private.h | 5 +- > > drivers/vfio/mdev/mdev_sysfs.c | 13 +++-- > > include/linux/mdev.h | 4 ++ > > 4 files changed, 111 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c > > index b558d4cfd082..e825ff38b037 100644 > > --- a/drivers/vfio/mdev/mdev_core.c > > +++ b/drivers/vfio/mdev/mdev_core.c > > @@ -10,9 +10,11 @@ > > #include <linux/module.h> > > #include <linux/device.h> > > #include <linux/slab.h> > > +#include <linux/mm.h> > > #include <linux/uuid.h> > > #include <linux/sysfs.h> > > #include <linux/mdev.h> > > +#include <crypto/hash.h> > > > > #include "mdev_private.h" > > > > @@ -27,6 +29,8 @@ static struct class_compat *mdev_bus_compat_class; > > static LIST_HEAD(mdev_list); > > static DEFINE_MUTEX(mdev_list_lock); > > > > +static struct crypto_shash *alias_hash; > > + > > struct device *mdev_parent_dev(struct mdev_device *mdev) > > { > > return mdev->parent->dev; > > @@ -164,6 +168,18 @@ int mdev_register_device(struct device *dev, const > > struct mdev_parent_ops *ops) > > goto add_dev_err; > > } > > > > + if (ops->get_alias_length) { > > + unsigned int digest_size; > > + unsigned int aligned_len; > > + > > + aligned_len = roundup(ops->get_alias_length(), 2); > > + digest_size = crypto_shash_digestsize(alias_hash); > > + if (aligned_len / 2 > digest_size) { > > + ret = -EINVAL; > > + goto add_dev_err; > > + } > > + } > > This looks like a sanity check, it could be done outside of the > parent_list_lock, even before we get a parent device reference. > > I think we're using a callback for get_alias_length() rather than a > fixed field to support the mtty module option added in patch 4, right? > Its utility is rather limited with no args. I could imagine that if a > parent wanted to generate an alias that could be incorporated into a > string with the parent device name that it would be useful to call this > with the parent device as an arg. I guess we can save that until a > user comes along though. > > There doesn't seem to be anything serializing use of alias_hash. > > > + > > parent = kzalloc(sizeof(*parent), GFP_KERNEL); > > if (!parent) { > > ret = -ENOMEM; > > @@ -259,6 +275,7 @@ static void mdev_device_free(struct mdev_device *mdev) > > mutex_unlock(&mdev_list_lock); > > > > dev_dbg(&mdev->dev, "MDEV: destroying\n"); > > + kvfree(mdev->alias); > > kfree(mdev); > > } > > > > @@ -269,18 +286,86 @@ static void mdev_device_release(struct device *dev) > > mdev_device_free(mdev); > > } > > > > -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 = 0; > > + > > + /* Align to multiple of 2 as bin2hex will generate > > + * even number of bytes. > > + */ > > Comment style for non-networking code please. > > > + alias_len = roundup(max_alias_len, 2); > > + alias = kvzalloc(alias_len + 1, GFP_KERNEL); Oops, here's the null termination of alias for the even case (+ 1), ignore the comment below about odd/even. Thanks, Alex > > The size we're generating here should be small enough to just use > kzalloc(), probably below too. > > > + if (!alias) > > + return NULL; > > + > > + /* Allocate and init descriptor */ > > + hash_desc = kvzalloc(sizeof(*hash_desc) + > > + crypto_shash_descsize(alias_hash), > > + GFP_KERNEL); > > + if (!hash_desc) > > + goto desc_err; > > + > > + hash_desc->tfm = alias_hash; > > + > > + digest_size = crypto_shash_digestsize(alias_hash); > > + > > + digest = kvzalloc(digest_size, GFP_KERNEL); > > + if (!digest) { > > + ret = -ENOMEM; > > + goto digest_err; > > + } > > + crypto_shash_init(hash_desc); > > + crypto_shash_update(hash_desc, uuid, UUID_STRING_LEN); > > + crypto_shash_final(hash_desc, digest); > > + bin2hex(&alias[0], digest, > > &alias[0], ie. alias > > > + min_t(unsigned int, digest_size, alias_len / 2)); > > + /* When alias length is odd, zero out and additional last byte > > + * that bin2hex has copied. > > + */ > > + if (max_alias_len % 2) > > + alias[max_alias_len] = 0; > > Doesn't this give us a null terminated string for odd numbers but not > even numbers? Probably best to define that we always provide a null > terminated string then we could do this unconditionally. > > > + > > + kvfree(digest); > > + kvfree(hash_desc); > > + return alias; > > + > > +digest_err: > > + kvfree(hash_desc); > > +desc_err: > > + kvfree(alias); > > + return NULL; > > +} > > + > > +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); > > + unsigned int alias_len = 0; > > + const char *alias = NULL; > > > > parent = mdev_get_parent(type->parent); > > if (!parent) > > return -EINVAL; > > > > + if (parent->ops->get_alias_length) > > + alias_len = parent->ops->get_alias_length(); > > + if (alias_len) { > > Why isn't this nested into the branch above? > > > + alias = generate_alias(uuid_str, alias_len); > > + if (!alias) { > > + ret = -ENOMEM; > > Could use an ERR_PTR and propagate an errno. > > > + goto alias_fail; > > + } > > + } > > + > > mutex_lock(&mdev_list_lock); > > > > /* Check for duplicate */ > > @@ -300,6 +385,8 @@ int mdev_device_create(struct kobject *kobj, > > } > > > > guid_copy(&mdev->uuid, uuid); > > + mdev->alias = alias; > > + alias = NULL; > > A comment justifying this null'ing might help prevent it getting culled > as some point. It appears arbitrary at first look. Thanks, > > Alex > > > list_add(&mdev->next, &mdev_list); > > mutex_unlock(&mdev_list_lock); > > > > @@ -346,6 +433,8 @@ int mdev_device_create(struct kobject *kobj, > > up_read(&parent->unreg_sem); > > put_device(&mdev->dev); > > mdev_fail: > > + kvfree(alias); > > +alias_fail: > > mdev_put_parent(parent); > > return ret; > > } > > @@ -406,6 +495,10 @@ EXPORT_SYMBOL(mdev_get_iommu_device); > > > > static int __init mdev_init(void) > > { > > + alias_hash = crypto_alloc_shash("sha1", 0, 0); > > + if (!alias_hash) > > + return -ENOMEM; > > + > > return mdev_bus_register(); > > } > > > > @@ -415,6 +508,7 @@ static void __exit mdev_exit(void) > > class_compat_unregister(mdev_bus_compat_class); > > > > mdev_bus_unregister(); > > + crypto_free_shash(alias_hash); > > } > > > > module_init(mdev_init) > > diff --git a/drivers/vfio/mdev/mdev_private.h > > b/drivers/vfio/mdev/mdev_private.h > > index 7d922950caaf..cf1c0d9842c6 100644 > > --- a/drivers/vfio/mdev/mdev_private.h > > +++ b/drivers/vfio/mdev/mdev_private.h > > @@ -33,6 +33,7 @@ struct mdev_device { > > struct kobject *type_kobj; > > struct device *iommu_device; > > bool active; > > + const char *alias; > > }; > > > > #define to_mdev_device(dev) container_of(dev, struct mdev_device, > > dev) > > @@ -57,8 +58,8 @@ void parent_remove_sysfs_files(struct mdev_parent > > *parent); > > int mdev_create_sysfs_files(struct device *dev, struct mdev_type *type); > > void mdev_remove_sysfs_files(struct device *dev, struct mdev_type *type); > > > > -int mdev_device_create(struct kobject *kobj, > > - struct device *dev, const guid_t *uuid); > > +int mdev_device_create(struct kobject *kobj, struct device *dev, > > + const char *uuid_str, const guid_t *uuid); > > int mdev_device_remove(struct device *dev); > > > > #endif /* MDEV_PRIVATE_H */ > > 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); > > if (ret) > > - return ret; > > + goto err; > > > > - return count; > > + ret = count; > > + > > +err: > > + kfree(str); > > + return ret; > > } > > > > MDEV_TYPE_ATTR_WO(create); > > diff --git a/include/linux/mdev.h b/include/linux/mdev.h > > index 0ce30ca78db0..f036fe9854ee 100644 > > --- a/include/linux/mdev.h > > +++ b/include/linux/mdev.h > > @@ -72,6 +72,9 @@ struct device *mdev_get_iommu_device(struct device *dev); > > * @mmap: mmap callback > > * @mdev: mediated device structure > > * @vma: vma structure > > + * @get_alias_length: Generate alias for the mdevs of this parent > > based on the > > + * mdev device name when it returns non zero alias length. > > + * It is optional. > > * Parent device that support mediated device should be registered with > > mdev > > * module with mdev_parent_ops structure. > > **/ > > @@ -92,6 +95,7 @@ struct mdev_parent_ops { > > long (*ioctl)(struct mdev_device *mdev, unsigned int cmd, > > unsigned long arg); > > int (*mmap)(struct mdev_device *mdev, struct vm_area_struct *vma); > > + unsigned int (*get_alias_length)(void); > > }; > > > > /* interface for exporting mdev supported type attributes */ >
