RE: [PATCH 06/10] iommu/ioasid: Convert to set aware allocations

["Tian, Kevin" <kevin.tian@intel.com>]

> 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?

>  	 */
> -	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?

>  			/* 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. 😊

> +	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...

> +		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

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