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    SubjectRe: [PATCH 06/10] iommu/ioasid: Convert to set aware allocations
    On Fri, 27 Mar 2020 09:54:11 +0000
    "Tian, Kevin" <kevin.tian@intel.com> wrote:

    > > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
    > > Sent: Thursday, March 26, 2020 1:55 AM
    > >
    > > The current ioasid_alloc function takes a token/ioasid_set then
    > > record it on the IOASID being allocated. There is no alloc/free on
    > > the ioasid_set.
    > >
    > > With the IOASID set APIs, callers must allocate an ioasid_set before
    > > allocate IOASIDs within the set. Quota and other ioasid_set level
    > > activities can then be enforced.
    > >
    > > This patch converts existing API to the new ioasid_set model.
    > >
    > > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
    > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
    > > ---
    > > drivers/iommu/intel-iommu.c | 10 +++---
    > > drivers/iommu/intel-svm.c | 10 +++---
    > > drivers/iommu/ioasid.c | 78
    > > +++++++++++++++++++++++++++++++++------- -----
    > > include/linux/ioasid.h | 11 +++----
    > > 4 files changed, 72 insertions(+), 37 deletions(-)
    > >
    > > diff --git a/drivers/iommu/intel-iommu.c
    > > b/drivers/iommu/intel-iommu.c index af7a1ef7b31e..c571cc8d9e57
    > > 100644 --- a/drivers/iommu/intel-iommu.c
    > > +++ b/drivers/iommu/intel-iommu.c
    > > @@ -3323,11 +3323,11 @@ static void intel_ioasid_free(ioasid_t
    > > ioasid, void *data)
    > > if (!iommu)
    > > return;
    > > /*
    > > - * Sanity check the ioasid owner is done at upper layer,
    > > e.g. VFIO
    > > - * We can only free the PASID when all the devices are
    > > unbound.
    > > + * In the guest, all IOASIDs belong to the system_ioasid
    > > set.
    > > + * Sanity check against the system set.
    >
    > below code has nothing to deal with guest, then why putting the
    > comment specifically for guest?
    >
    intel_ioasid_alloc/free() is the custom IOASID allocator only
    registered when running in the guest.

    The custom allocator calls virtual command. Since we don't support
    nested guest, all IOASIDs belong to the system ioasid_set.

    > > */
    > > - if (ioasid_find(NULL, ioasid, NULL)) {
    > > - pr_alert("Cannot free active IOASID %d\n", ioasid);
    > > + if (IS_ERR(ioasid_find(system_ioasid_sid, ioasid, NULL))) {
    > > + pr_err("Cannot free IOASID %d, not in system
    > > set\n", ioasid); return;
    > > }
    > > vcmd_free_pasid(iommu, ioasid);
    > > @@ -5541,7 +5541,7 @@ static int aux_domain_add_dev(struct
    > > dmar_domain *domain,
    > > int pasid;
    > >
    > > /* No private data needed for the default pasid */
    > > - pasid = ioasid_alloc(NULL, PASID_MIN,
    > > + pasid = ioasid_alloc(system_ioasid_sid, PASID_MIN,
    > > pci_max_pasids(to_pci_dev(dev))
    > > - 1, NULL);
    > > if (pasid == INVALID_IOASID) {
    > > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
    > > index 1991587fd3fd..f511855d187b 100644
    > > --- a/drivers/iommu/intel-svm.c
    > > +++ b/drivers/iommu/intel-svm.c
    > > @@ -268,7 +268,7 @@ int intel_svm_bind_gpasid(struct iommu_domain
    > > *domain,
    > > }
    > >
    > > mutex_lock(&pasid_mutex);
    > > - svm = ioasid_find(NULL, data->hpasid, NULL);
    > > + svm = ioasid_find(INVALID_IOASID_SET, data->hpasid, NULL);
    > > if (IS_ERR(svm)) {
    > > ret = PTR_ERR(svm);
    > > goto out;
    > > @@ -401,7 +401,7 @@ int intel_svm_unbind_gpasid(struct device *dev,
    > > int pasid)
    > > return -EINVAL;
    > >
    > > mutex_lock(&pasid_mutex);
    > > - svm = ioasid_find(NULL, pasid, NULL);
    > > + svm = ioasid_find(INVALID_IOASID_SET, pasid, NULL);
    > > if (!svm) {
    > > ret = -EINVAL;
    > > goto out;
    > > @@ -559,7 +559,7 @@ static int intel_svm_bind_mm(struct device
    > > *dev, int flags, struct svm_dev_ops *
    > > pasid_max = intel_pasid_max_id;
    > >
    > > /* Do not use PASID 0, reserved for RID to PASID */
    > > - svm->pasid = ioasid_alloc(NULL, PASID_MIN,
    > > + svm->pasid = ioasid_alloc(system_ioasid_sid,
    > > PASID_MIN, pasid_max - 1, svm);
    > > if (svm->pasid == INVALID_IOASID) {
    > > kfree(svm);
    > > @@ -642,7 +642,7 @@ int intel_svm_unbind_mm(struct device *dev, int
    > > pasid)
    > > if (!iommu)
    > > goto out;
    > >
    > > - svm = ioasid_find(NULL, pasid, NULL);
    > > + svm = ioasid_find(system_ioasid_sid, pasid, NULL);
    > > if (!svm)
    > > goto out;
    > >
    > > @@ -778,7 +778,7 @@ static irqreturn_t prq_event_thread(int irq,
    > > void *d)
    > >
    > > if (!svm || svm->pasid != req->pasid) {
    > > rcu_read_lock();
    > > - svm = ioasid_find(NULL, req->pasid, NULL);
    > > + svm = ioasid_find(INVALID_IOASID_SET,
    > > req->pasid, NULL);
    >
    > is there a criteria when INVALID_IOASID_SET should be used?
    >
    Two use cases for INVALID_IOASID_SET:
    1. a hint to ioasid_find to do global search, ignore set ownership check
    2. cannot find a set ID for a given ioasid_find_sid()

    You brought up a good point, I missed the second use case.


    > > /* It *can't* go away, because the driver
    > > is not permitted
    > > * to unbind the mm while any page faults
    > > are outstanding.
    > > * So we only need RCU to protect the
    > > internal idr code. */
    > > diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
    > > index 9135af171a7c..f89a595f6978 100644
    > > --- a/drivers/iommu/ioasid.c
    > > +++ b/drivers/iommu/ioasid.c
    > > @@ -31,7 +31,7 @@ struct ioasid_set_data {
    > >
    > > struct ioasid_data {
    > > ioasid_t id;
    > > - struct ioasid_set *set;
    > > + struct ioasid_set_data *sdata;
    > > void *private;
    > > struct rcu_head rcu;
    > > };
    > > @@ -334,7 +334,7 @@ EXPORT_SYMBOL_GPL(ioasid_attach_data);
    > >
    > > /**
    > > * ioasid_alloc - Allocate an IOASID
    > > - * @set: the IOASID set
    > > + * @sid: the IOASID set ID
    > > * @min: the minimum ID (inclusive)
    > > * @max: the maximum ID (inclusive)
    > > * @private: data private to the caller
    > > @@ -344,18 +344,30 @@ EXPORT_SYMBOL_GPL(ioasid_attach_data);
    > > *
    > > * Return: the allocated ID on success, or %INVALID_IOASID on
    > > failure. */
    > > -ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min,
    > > ioasid_t max,
    > > - void *private)
    > > +ioasid_t ioasid_alloc(int sid, ioasid_t min, ioasid_t max, void
    > > *private) {
    > > + struct ioasid_set_data *sdata;
    > > struct ioasid_data *data;
    > > void *adata;
    > > ioasid_t id;
    > >
    > > - data = kzalloc(sizeof(*data), GFP_ATOMIC);
    > > + /* Check if the IOASID set has been allocated and
    > > initialized */
    > > + sdata = xa_load(&ioasid_sets, sid);
    >
    > ok, this change answers my previous question in last patch. 😊
    >
    I guess you meant the NULL set question?

    > > + if (!sdata) {
    > > + pr_err("Invalid IOASID set %d to allocate from\n",
    > > sid);
    > > + return INVALID_IOASID;
    > > + }
    > > +
    > > + if (sdata->size <= sdata->nr_ioasids) {
    > > + pr_err("IOASID set %d out of quota\n", sid);
    > > + return INVALID_IOASID;
    > > + }
    > > +
    > > + data = kzalloc(sizeof(*data), GFP_KERNEL);
    > > if (!data)
    > > return INVALID_IOASID;
    > >
    > > - data->set = set;
    > > + data->sdata = sdata;
    > > data->private = private;
    > >
    > > /*
    > > @@ -379,6 +391,9 @@ ioasid_t ioasid_alloc(struct ioasid_set *set,
    > > ioasid_t min, ioasid_t max,
    > > }
    > > data->id = id;
    > >
    > > + /* Store IOASID in the per set data */
    > > + xa_store(&sdata->xa, id, data, GFP_KERNEL);
    > > + sdata->nr_ioasids++;
    > > spin_unlock(&ioasid_allocator_lock);
    > > return id;
    > > exit_free:
    > > @@ -388,19 +403,15 @@ ioasid_t ioasid_alloc(struct ioasid_set *set,
    > > ioasid_t min, ioasid_t max,
    > > }
    > > EXPORT_SYMBOL_GPL(ioasid_alloc);
    > >
    > > -/**
    > > - * ioasid_free - Free an IOASID
    > > - * @ioasid: the ID to remove
    > > - */
    > > -void ioasid_free(ioasid_t ioasid)
    > > +static void ioasid_free_locked(ioasid_t ioasid)
    > > {
    > > struct ioasid_data *ioasid_data;
    > > + struct ioasid_set_data *sdata;
    > >
    > > - spin_lock(&ioasid_allocator_lock);
    > > ioasid_data = xa_load(&active_allocator->xa, ioasid);
    > > if (!ioasid_data) {
    > > pr_err("Trying to free unknown IOASID %u\n",
    > > ioasid);
    > > - goto exit_unlock;
    > > + return;
    > > }
    > >
    > > active_allocator->ops->free(ioasid,
    > > active_allocator->ops->pdata); @@ -410,7 +421,27 @@ void
    > > ioasid_free(ioasid_t ioasid) kfree_rcu(ioasid_data, rcu);
    > > }
    > >
    > > -exit_unlock:
    > > + sdata = xa_load(&ioasid_sets, ioasid_data->sdata->sid);
    > > + if (!sdata) {
    > > + pr_err("No set %d for IOASID %d\n",
    > > ioasid_data->sdata->sid,
    > > + ioasid);
    > > + return;
    > > + }
    > > + xa_erase(&sdata->xa, ioasid);
    > > + sdata->nr_ioasids--;
    > > +}
    > > +
    > > +/**
    > > + * ioasid_free - Free an IOASID and notify users who registered a
    > > notifier
    > > + * on the IOASID set.
    > > + * IOASID can be re-allocated upon return
    > > + *
    > > + * @ioasid: the ID to remove
    > > + */
    > > +void ioasid_free(ioasid_t ioasid)
    > > +{
    > > + spin_lock(&ioasid_allocator_lock);
    > > + ioasid_free_locked(ioasid);
    > > spin_unlock(&ioasid_allocator_lock);
    > > }
    > > EXPORT_SYMBOL_GPL(ioasid_free);
    > > @@ -499,8 +530,12 @@ void ioasid_free_set(int sid, bool destroy_set)
    > > goto done_destroy;
    > > }
    > >
    > > - /* Just a place holder for now */
    > > xa_for_each(&sdata->xa, index, entry) {
    > > + /*
    > > + * Free from system-wide IOASID pool, all
    > > subscribers gets
    > > + * notified and do cleanup.
    > > + */
    >
    > this comment might be added too early...
    Yes, I should move it to notifier patch.

    >
    > > + ioasid_free_locked(index);
    > > /* Free from per sub-set pool */
    > > xa_erase(&sdata->xa, index);
    > > }
    > > @@ -508,7 +543,6 @@ void ioasid_free_set(int sid, bool destroy_set)
    > > 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);
    > > @@ -522,7 +556,7 @@ EXPORT_SYMBOL_GPL(ioasid_free_set);
    > >
    > > /**
    > > * ioasid_find - Find IOASID data
    > > - * @set: the IOASID set
    > > + * @sid: the IOASID set ID
    > > * @ioasid: the IOASID to find
    > > * @getter: function to call on the found object
    > > *
    > > @@ -532,10 +566,12 @@ EXPORT_SYMBOL_GPL(ioasid_free_set);
    > > *
    > > * If the IOASID exists, return the private pointer passed to
    > > ioasid_alloc.
    > > * Private data can be NULL if not set. Return an error if the
    > > IOASID is not
    > > - * found, or if @set is not NULL and the IOASID does not belong to
    > > the set.
    > > + * found.
    > > + *
    > > + * If sid is INVALID_IOASID_SET, it will skip set ownership
    > > checking. Otherwise,
    > > + * error is returned even if the IOASID is found but does not
    > > belong the set. */
    > > -void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,
    > > - bool (*getter)(void *))
    > > +void *ioasid_find(int sid, ioasid_t ioasid, bool (*getter)(void *))
    > > {
    > > void *priv;
    > > struct ioasid_data *ioasid_data;
    > > @@ -548,7 +584,7 @@ void *ioasid_find(struct ioasid_set *set,
    > > ioasid_t ioasid,
    > > priv = ERR_PTR(-ENOENT);
    > > goto unlock;
    > > }
    > > - if (set && ioasid_data->set != set) {
    > > + if (sid != INVALID_IOASID_SET &&
    > > ioasid_data->sdata->sid != sid) { /* data found but does not belong
    > > to the set */ priv = ERR_PTR(-EACCES);
    > > goto unlock;
    > > diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
    > > index 097b1cc043a3..e19c0ad93bd7 100644
    > > --- a/include/linux/ioasid.h
    > > +++ b/include/linux/ioasid.h
    > > @@ -6,6 +6,7 @@
    > > #include <linux/errno.h>
    > >
    > > #define INVALID_IOASID ((ioasid_t)-1)
    > > +#define INVALID_IOASID_SET (-1)
    > > typedef unsigned int ioasid_t;
    > > typedef ioasid_t (*ioasid_alloc_fn_t)(ioasid_t min, ioasid_t max,
    > > void *data); typedef void (*ioasid_free_fn_t)(ioasid_t ioasid, void
    > > *data); @@ -35,11 +36,10 @@ extern int system_ioasid_sid;
    > > #define DECLARE_IOASID_SET(name) struct ioasid_set name = { 0 }
    > >
    > > #if IS_ENABLED(CONFIG_IOASID)
    > > -ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min,
    > > ioasid_t max, +ioasid_t ioasid_alloc(int sid, ioasid_t min,
    > > ioasid_t max, void *private);
    > > void ioasid_free(ioasid_t ioasid);
    > > -void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,
    > > - bool (*getter)(void *));
    > > +void *ioasid_find(int sid, ioasid_t ioasid, bool (*getter)(void
    > > *)); int ioasid_register_allocator(struct ioasid_allocator_ops
    > > *allocator); void ioasid_unregister_allocator(struct
    > > ioasid_allocator_ops *allocator); int ioasid_attach_data(ioasid_t
    > > ioasid, void *data); @@ -49,7 +49,7 @@ 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, +static inline ioasid_t ioasid_alloc(int sid,
    > > ioasid_t min, ioasid_t max, void *private)
    > > {
    > > return INVALID_IOASID;
    > > @@ -68,8 +68,7 @@ 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 *))
    > > +static inline void *ioasid_find(int sid, ioasid_t ioasid, bool
    > > (*getter)(void *)) {
    > > return NULL;
    > > }
    > > --
    > > 2.7.4
    >

    [Jacob Pan]

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