Messages in this thread | | | Date | Wed, 1 Apr 2020 15:47:45 +0200 | From | Jean-Philippe Brucker <> | Subject | Re: [PATCH 03/10] iommu/ioasid: Introduce per set allocation APIs |
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On Wed, Mar 25, 2020 at 10:55:24AM -0700, Jacob Pan wrote: > IOASID set defines a group of IDs that share the same token. The > ioasid_set concept helps to do permission checking among users as in the > current code. > > With guest SVA usage, each VM has its own IOASID set. More > functionalities are needed: > 1. Enforce quota, each guest may be assigned limited quota such that one > guest cannot abuse all the system resource. > 2. Stores IOASID mapping between guest and host IOASIDs > 3. Per set operations, e.g. free the entire set > > For each ioasid_set token, a unique set ID is assigned. This makes > reference of the set and data lookup much easier to implement. > > Signed-off-by: Liu Yi L <yi.l.liu@intel.com> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> > --- > drivers/iommu/ioasid.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/ioasid.h | 13 +++++ > 2 files changed, 160 insertions(+) > > diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c > index 4026e52855b9..27ee57f7079b 100644 > --- a/drivers/iommu/ioasid.c > +++ b/drivers/iommu/ioasid.c > @@ -10,6 +10,25 @@ > #include <linux/spinlock.h> > #include <linux/xarray.h> > > +static DEFINE_XARRAY_ALLOC(ioasid_sets); > +/** > + * struct ioasid_set_data - Meta data about ioasid_set > + * > + * @token: Unique to identify an IOASID set > + * @xa: XArray to store subset ID and IOASID mapping > + * @size: Max number of IOASIDs can be allocated within the set > + * @nr_ioasids Number of IOASIDs allocated in the set > + * @sid ID of the set > + */ > +struct ioasid_set_data { > + struct ioasid_set *token; > + struct xarray xa; > + int size; > + int nr_ioasids; > + int sid; > + struct rcu_head rcu; > +}; > + > struct ioasid_data { > ioasid_t id; > struct ioasid_set *set; > @@ -388,6 +407,111 @@ void ioasid_free(ioasid_t ioasid) > EXPORT_SYMBOL_GPL(ioasid_free); > > /** > + * ioasid_alloc_set - Allocate a set of IOASIDs > + * @token: Unique token of the IOASID set > + * @quota: Quota allowed in this set > + * @sid: IOASID set ID to be assigned > + * > + * Return 0 upon success. Token will be stored internally for lookup, > + * IOASID allocation within the set and other per set operations will use > + * the @sid assigned. > + * > + */ > +int ioasid_alloc_set(struct ioasid_set *token, ioasid_t quota, int *sid) > +{ > + struct ioasid_set_data *sdata; > + ioasid_t id; > + int ret = 0; > + > + if (quota > ioasid_capacity_avail) { > + pr_warn("Out of IOASID capacity! ask %d, avail %d\n", > + quota, ioasid_capacity_avail); > + return -ENOSPC; > + }
This check should be in the same critical section as the quota substraction
> + > + sdata = kzalloc(sizeof(*sdata), GFP_KERNEL); > + if (!sdata) > + return -ENOMEM;
I don't understand why we need this structure at all, nor why we need the SID. Users have already allocated an ioasid_set, so why not just stick the content of ioasid_set_data in there, and pass the ioasid_set pointer to ioasid_alloc()?
> + > + spin_lock(&ioasid_allocator_lock); > + > + ret = xa_alloc(&ioasid_sets, &id, sdata, > + XA_LIMIT(0, ioasid_capacity_avail - quota), > + GFP_KERNEL);
Same as Kevin, I think the limit should be the static ioasid_capacity. And perhaps a comment explaining the worst case of one PASID per set. I found a little confusing using the same type ioasid_t for IOASIDs and IOASID sets, it may be clearer to use an int for IOASID set IDs.
Thanks, Jean
> + if (ret) { > + kfree(sdata); > + goto error; > + } > + > + sdata->token = token; > + sdata->size = quota; > + sdata->sid = id; > + > + /* > + * Set Xarray is used to store IDs within the set, get ready for > + * sub-set ID and system-wide IOASID allocation results. > + */ > + xa_init_flags(&sdata->xa, XA_FLAGS_ALLOC); > + > + ioasid_capacity_avail -= quota; > + *sid = id; > + > +error: > + spin_unlock(&ioasid_allocator_lock); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(ioasid_alloc_set); > + > +/** > + * ioasid_free_set - Free all IOASIDs within the set > + * > + * @sid: The IOASID set ID to be freed > + * @destroy_set: Whether to keep the set for further allocation. > + * If true, the set will be destroyed. > + * > + * All IOASIDs allocated within the set will be freed upon return. > + */ > +void ioasid_free_set(int sid, bool destroy_set) > +{ > + struct ioasid_set_data *sdata; > + struct ioasid_data *entry; > + unsigned long index; > + > + spin_lock(&ioasid_allocator_lock); > + sdata = xa_load(&ioasid_sets, sid); > + if (!sdata) { > + pr_err("No IOASID set found to free %d\n", sid); > + goto done_unlock; > + } > + > + if (xa_empty(&sdata->xa)) { > + pr_warn("No IOASIDs in the set %d\n", sdata->sid); > + goto done_destroy; > + } > + > + /* Just a place holder for now */ > + xa_for_each(&sdata->xa, index, entry) { > + /* Free from per sub-set pool */ > + xa_erase(&sdata->xa, index); > + } > + > +done_destroy: > + if (destroy_set) { > + xa_erase(&ioasid_sets, sid); > + > + /* Return the quota back to system pool */ > + ioasid_capacity_avail += sdata->size; > + kfree_rcu(sdata, rcu); > + } > + > +done_unlock: > + spin_unlock(&ioasid_allocator_lock); > +} > +EXPORT_SYMBOL_GPL(ioasid_free_set); > + > + > +/** > * ioasid_find - Find IOASID data > * @set: the IOASID set > * @ioasid: the IOASID to find > @@ -431,6 +555,29 @@ void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, > } > EXPORT_SYMBOL_GPL(ioasid_find); > > +/** > + * ioasid_find_sid - Retrieve IOASID set ID from an ioasid > + * Caller must hold a reference to the set. > + * > + * @ioasid: IOASID associated with the set > + * > + * Return IOASID set ID or error > + */ > +int ioasid_find_sid(ioasid_t ioasid) > +{ > + struct ioasid_data *ioasid_data; > + int ret = 0; > + > + spin_lock(&ioasid_allocator_lock); > + ioasid_data = xa_load(&active_allocator->xa, ioasid); > + ret = (ioasid_data) ? ioasid_data->sdata->sid : -ENOENT; > + > + spin_unlock(&ioasid_allocator_lock); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(ioasid_find_sid); > + > MODULE_AUTHOR("Jean-Philippe Brucker <jean-philippe.brucker@arm.com>"); > MODULE_AUTHOR("Jacob Pan <jacob.jun.pan@linux.intel.com>"); > MODULE_DESCRIPTION("IO Address Space ID (IOASID) allocator"); > diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h > index 9711fa0dc357..be158e03c034 100644 > --- a/include/linux/ioasid.h > +++ b/include/linux/ioasid.h > @@ -41,6 +41,9 @@ int ioasid_register_allocator(struct ioasid_allocator_ops *allocator); > void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator); > int ioasid_set_data(ioasid_t ioasid, void *data); > void ioasid_install_capacity(ioasid_t total); > +int ioasid_alloc_set(struct ioasid_set *token, ioasid_t quota, int *sid); > +void ioasid_free_set(int sid, bool destroy_set); > +int ioasid_find_sid(ioasid_t ioasid); > #else /* !CONFIG_IOASID */ > static inline ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, > ioasid_t max, void *private) > @@ -52,6 +55,15 @@ static inline void ioasid_free(ioasid_t ioasid) > { > } > > +static inline int ioasid_alloc_set(struct ioasid_set *token, ioasid_t quota, int *sid) > +{ > + return -ENOTSUPP; > +} > + > +static inline void ioasid_free_set(int sid, bool destroy_set) > +{ > +} > + > static inline void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, > bool (*getter)(void *)) > { > @@ -75,5 +87,6 @@ static inline int ioasid_set_data(ioasid_t ioasid, void *data) > static inline void ioasid_install_capacity(ioasid_t total) > { > } > + > #endif /* CONFIG_IOASID */ > #endif /* __LINUX_IOASID_H */ > -- > 2.7.4 >
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