diff options
author | Fenghua Yu <fenghua.yu@intel.com> | 2022-02-07 15:02:48 -0800 |
---|---|---|
committer | Borislav Petkov <bp@suse.de> | 2022-02-15 11:31:35 +0100 |
commit | 701fac40384f07197b106136012804c3cae0b3de (patch) | |
tree | 1637d8cc005e07c28f7357b8a6dd8c538c9f5967 /drivers/iommu | |
parent | a6cbd44093ef305b02ad5f80ed54abf0148a696c (diff) | |
download | linux-701fac40384f07197b106136012804c3cae0b3de.tar.bz2 |
iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit
PASIDs are process-wide. It was attempted to use refcounted PASIDs to
free them when the last thread drops the refcount. This turned out to
be complex and error prone. Given the fact that the PASID space is 20
bits, which allows up to 1M processes to have a PASID associated
concurrently, PASID resource exhaustion is not a realistic concern.
Therefore, it was decided to simplify the approach and stick with lazy
on demand PASID allocation, but drop the eager free approach and make an
allocated PASID's lifetime bound to the lifetime of the process.
Get rid of the refcounting mechanisms and replace/rename the interfaces
to reflect this new approach.
[ bp: Massage commit message. ]
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-6-fenghua.yu@intel.com
Diffstat (limited to 'drivers/iommu')
-rw-r--r-- | drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 5 | ||||
-rw-r--r-- | drivers/iommu/intel/iommu.c | 4 | ||||
-rw-r--r-- | drivers/iommu/intel/svm.c | 9 | ||||
-rw-r--r-- | drivers/iommu/ioasid.c | 39 | ||||
-rw-r--r-- | drivers/iommu/iommu-sva-lib.c | 39 | ||||
-rw-r--r-- | drivers/iommu/iommu-sva-lib.h | 1 |
6 files changed, 19 insertions, 78 deletions
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c index a737ba5f727e..22ddd05bbdcd 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c @@ -340,14 +340,12 @@ __arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm) bond->smmu_mn = arm_smmu_mmu_notifier_get(smmu_domain, mm); if (IS_ERR(bond->smmu_mn)) { ret = PTR_ERR(bond->smmu_mn); - goto err_free_pasid; + goto err_free_bond; } list_add(&bond->list, &master->bonds); return &bond->sva; -err_free_pasid: - iommu_sva_free_pasid(mm); err_free_bond: kfree(bond); return ERR_PTR(ret); @@ -377,7 +375,6 @@ void arm_smmu_sva_unbind(struct iommu_sva *handle) if (refcount_dec_and_test(&bond->refs)) { list_del(&bond->list); arm_smmu_mmu_notifier_put(bond->smmu_mn); - iommu_sva_free_pasid(bond->mm); kfree(bond); } mutex_unlock(&sva_lock); diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 92fea3fbbb11..ef03b2176bbd 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -4781,7 +4781,7 @@ attach_failed: link_failed: spin_unlock_irqrestore(&device_domain_lock, flags); if (list_empty(&domain->subdevices) && domain->default_pasid > 0) - ioasid_put(domain->default_pasid); + ioasid_free(domain->default_pasid); return ret; } @@ -4811,7 +4811,7 @@ static void aux_domain_remove_dev(struct dmar_domain *domain, spin_unlock_irqrestore(&device_domain_lock, flags); if (list_empty(&domain->subdevices) && domain->default_pasid > 0) - ioasid_put(domain->default_pasid); + ioasid_free(domain->default_pasid); } static int prepare_domain_attach_device(struct iommu_domain *domain, diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c index 5b5d69b04fcc..51ac2096b3da 100644 --- a/drivers/iommu/intel/svm.c +++ b/drivers/iommu/intel/svm.c @@ -514,11 +514,6 @@ static int intel_svm_alloc_pasid(struct device *dev, struct mm_struct *mm, return iommu_sva_alloc_pasid(mm, PASID_MIN, max_pasid - 1); } -static void intel_svm_free_pasid(struct mm_struct *mm) -{ - iommu_sva_free_pasid(mm); -} - static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu, struct device *dev, struct mm_struct *mm, @@ -662,8 +657,6 @@ static int intel_svm_unbind_mm(struct device *dev, u32 pasid) kfree(svm); } } - /* Drop a PASID reference and free it if no reference. */ - intel_svm_free_pasid(mm); } out: return ret; @@ -1047,8 +1040,6 @@ struct iommu_sva *intel_svm_bind(struct device *dev, struct mm_struct *mm, void } sva = intel_svm_bind_mm(iommu, dev, mm, flags); - if (IS_ERR_OR_NULL(sva)) - intel_svm_free_pasid(mm); mutex_unlock(&pasid_mutex); return sva; diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c index 06fee7416816..a786c034907c 100644 --- a/drivers/iommu/ioasid.c +++ b/drivers/iommu/ioasid.c @@ -2,7 +2,7 @@ /* * I/O Address Space ID allocator. There is one global IOASID space, split into * subsets. Users create a subset with DECLARE_IOASID_SET, then allocate and - * free IOASIDs with ioasid_alloc and ioasid_put. + * free IOASIDs with ioasid_alloc() and ioasid_free(). */ #include <linux/ioasid.h> #include <linux/module.h> @@ -15,7 +15,6 @@ struct ioasid_data { struct ioasid_set *set; void *private; struct rcu_head rcu; - refcount_t refs; }; /* @@ -315,7 +314,6 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, data->set = set; data->private = private; - refcount_set(&data->refs, 1); /* * Custom allocator needs allocator data to perform platform specific @@ -348,35 +346,11 @@ exit_free: EXPORT_SYMBOL_GPL(ioasid_alloc); /** - * ioasid_get - obtain a reference to the IOASID - * @ioasid: the ID to get - */ -void ioasid_get(ioasid_t ioasid) -{ - struct ioasid_data *ioasid_data; - - spin_lock(&ioasid_allocator_lock); - ioasid_data = xa_load(&active_allocator->xa, ioasid); - if (ioasid_data) - refcount_inc(&ioasid_data->refs); - else - WARN_ON(1); - spin_unlock(&ioasid_allocator_lock); -} -EXPORT_SYMBOL_GPL(ioasid_get); - -/** - * ioasid_put - Release a reference to an ioasid + * ioasid_free - Free an ioasid * @ioasid: the ID to remove - * - * Put a reference to the IOASID, free it when the number of references drops to - * zero. - * - * Return: %true if the IOASID was freed, %false otherwise. */ -bool ioasid_put(ioasid_t ioasid) +void ioasid_free(ioasid_t ioasid) { - bool free = false; struct ioasid_data *ioasid_data; spin_lock(&ioasid_allocator_lock); @@ -386,10 +360,6 @@ bool ioasid_put(ioasid_t ioasid) goto exit_unlock; } - free = refcount_dec_and_test(&ioasid_data->refs); - if (!free) - goto exit_unlock; - active_allocator->ops->free(ioasid, active_allocator->ops->pdata); /* Custom allocator needs additional steps to free the xa element */ if (active_allocator->flags & IOASID_ALLOCATOR_CUSTOM) { @@ -399,9 +369,8 @@ bool ioasid_put(ioasid_t ioasid) exit_unlock: spin_unlock(&ioasid_allocator_lock); - return free; } -EXPORT_SYMBOL_GPL(ioasid_put); +EXPORT_SYMBOL_GPL(ioasid_free); /** * ioasid_find - Find IOASID data diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c index bd41405d34e9..106506143896 100644 --- a/drivers/iommu/iommu-sva-lib.c +++ b/drivers/iommu/iommu-sva-lib.c @@ -18,8 +18,7 @@ static DECLARE_IOASID_SET(iommu_sva_pasid); * * Try to allocate a PASID for this mm, or take a reference to the existing one * provided it fits within the [@min, @max] range. On success the PASID is - * available in mm->pasid, and must be released with iommu_sva_free_pasid(). - * @min must be greater than 0, because 0 indicates an unused mm->pasid. + * available in mm->pasid and will be available for the lifetime of the mm. * * Returns 0 on success and < 0 on error. */ @@ -33,38 +32,24 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max) return -EINVAL; mutex_lock(&iommu_sva_lock); - if (mm->pasid) { - if (mm->pasid >= min && mm->pasid <= max) - ioasid_get(mm->pasid); - else + /* Is a PASID already associated with this mm? */ + if (pasid_valid(mm->pasid)) { + if (mm->pasid < min || mm->pasid >= max) ret = -EOVERFLOW; - } else { - pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm); - if (pasid == INVALID_IOASID) - ret = -ENOMEM; - else - mm->pasid = pasid; + goto out; } + + pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm); + if (!pasid_valid(pasid)) + ret = -ENOMEM; + else + mm_pasid_set(mm, pasid); +out: mutex_unlock(&iommu_sva_lock); return ret; } EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid); -/** - * iommu_sva_free_pasid - Release the mm's PASID - * @mm: the mm - * - * Drop one reference to a PASID allocated with iommu_sva_alloc_pasid() - */ -void iommu_sva_free_pasid(struct mm_struct *mm) -{ - mutex_lock(&iommu_sva_lock); - if (ioasid_put(mm->pasid)) - mm->pasid = 0; - mutex_unlock(&iommu_sva_lock); -} -EXPORT_SYMBOL_GPL(iommu_sva_free_pasid); - /* ioasid_find getter() requires a void * argument */ static bool __mmget_not_zero(void *mm) { diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h index 95dc3ebc1928..8909ea1094e3 100644 --- a/drivers/iommu/iommu-sva-lib.h +++ b/drivers/iommu/iommu-sva-lib.h @@ -9,7 +9,6 @@ #include <linux/mm_types.h> int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max); -void iommu_sva_free_pasid(struct mm_struct *mm); struct mm_struct *iommu_sva_find(ioasid_t pasid); /* I/O Page fault */ |