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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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