iommu: Move global PASID allocation from SVA to core

Intel ENQCMD requires a single PASID to be shared between multiple
devices, as the PASID is stored in a single MSR register per-process
and userspace can use only that one PASID.

This means that the PASID allocation for any ENQCMD using device driver
must always come from a shared global pool, regardless of what kind of
domain the PASID will be used with.

Split the code for the global PASID allocator into
iommu_alloc/free_global_pasid() so that drivers can attach non-SVA
domains to PASIDs as well.

This patch moves global PASID allocation APIs from SVA to IOMMU APIs.
Reserved PASIDs, currently only RID_PASID, are excluded from the global
PASID allocation.

It is expected that device drivers will use the allocated PASIDs to
attach to appropriate IOMMU domains for use.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20230802212427.1497170-3-jacob.jun.pan@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 05c0fb2..b78671a 100644 (file)
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -10,34 +10,30 @@
 #include "iommu-sva.h"
 
 static DEFINE_MUTEX(iommu_sva_lock);
-static DEFINE_IDA(iommu_global_pasid_ida);
 
 /* Allocate a PASID for the mm within range (inclusive) */
-static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
+static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
 {
+       ioasid_t pasid;
        int ret = 0;
 
-       if (min == IOMMU_PASID_INVALID ||
-           max == IOMMU_PASID_INVALID ||
-           min == 0 || max < min)
-               return -EINVAL;
-
        if (!arch_pgtable_dma_compat(mm))
                return -EBUSY;
 
        mutex_lock(&iommu_sva_lock);
        /* Is a PASID already associated with this mm? */
        if (mm_valid_pasid(mm)) {
-               if (mm->pasid < min || mm->pasid > max)
+               if (mm->pasid >= dev->iommu->max_pasids)
                        ret = -EOVERFLOW;
                goto out;
        }
 
-       ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL);
-       if (ret < 0)
+       pasid = iommu_alloc_global_pasid(dev);
+       if (pasid == IOMMU_PASID_INVALID) {
+               ret = -ENOSPC;
                goto out;
-
-       mm->pasid = ret;
+       }
+       mm->pasid = pasid;
        ret = 0;
 out:
        mutex_unlock(&iommu_sva_lock);
@@ -64,15 +60,10 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 {
        struct iommu_domain *domain;
        struct iommu_sva *handle;
-       ioasid_t max_pasids;
        int ret;
 
-       max_pasids = dev->iommu->max_pasids;
-       if (!max_pasids)
-               return ERR_PTR(-EOPNOTSUPP);
-
        /* Allocate mm->pasid if necessary. */
-       ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
+       ret = iommu_sva_alloc_pasid(mm, dev);
        if (ret)
                return ERR_PTR(ret);
 
@@ -217,5 +208,5 @@ void mm_pasid_drop(struct mm_struct *mm)
        if (likely(!mm_valid_pasid(mm)))
                return;
 
-       ida_free(&iommu_global_pasid_ida, mm->pasid);
+       iommu_free_global_pasid(mm->pasid);
 }

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index caaf563..d199d14 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -39,6 +39,7 @@
 
 static struct kset *iommu_group_kset;
 static DEFINE_IDA(iommu_group_ida);
+static DEFINE_IDA(iommu_global_pasid_ida);
 
 static unsigned int iommu_def_domain_type __read_mostly;
 static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_DMA_STRICT);
@@ -3400,3 +3401,30 @@ struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
 
        return domain;
 }
+
+ioasid_t iommu_alloc_global_pasid(struct device *dev)
+{
+       int ret;
+
+       /* max_pasids == 0 means that the device does not support PASID */
+       if (!dev->iommu->max_pasids)
+               return IOMMU_PASID_INVALID;
+
+       /*
+        * max_pasids is set up by vendor driver based on number of PASID bits
+        * supported but the IDA allocation is inclusive.
+        */
+       ret = ida_alloc_range(&iommu_global_pasid_ida, IOMMU_FIRST_GLOBAL_PASID,
+                             dev->iommu->max_pasids - 1, GFP_KERNEL);
+       return ret < 0 ? IOMMU_PASID_INVALID : ret;
+}
+EXPORT_SYMBOL_GPL(iommu_alloc_global_pasid);
+
+void iommu_free_global_pasid(ioasid_t pasid)
+{
+       if (WARN_ON(pasid == IOMMU_PASID_INVALID))
+               return;
+
+       ida_free(&iommu_global_pasid_ida, pasid);
+}
+EXPORT_SYMBOL_GPL(iommu_free_global_pasid);

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 2870bc2..6b821cb 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -197,6 +197,7 @@ enum iommu_dev_features {
 };
 
 #define IOMMU_NO_PASID (0U) /* Reserved for DMA w/o PASID */
+#define IOMMU_FIRST_GLOBAL_PASID       (1U) /*starting range for allocation */
 #define IOMMU_PASID_INVALID    (-1U)
 typedef unsigned int ioasid_t;
 
@@ -728,6 +729,8 @@ void iommu_detach_device_pasid(struct iommu_domain *domain,
 struct iommu_domain *
 iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid,
                               unsigned int type);
+ioasid_t iommu_alloc_global_pasid(struct device *dev);
+void iommu_free_global_pasid(ioasid_t pasid);
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
@@ -1089,6 +1092,13 @@ iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid,
 {
        return NULL;
 }
+
+static inline ioasid_t iommu_alloc_global_pasid(struct device *dev)
+{
+       return IOMMU_PASID_INVALID;
+}
+
+static inline void iommu_free_global_pasid(ioasid_t pasid) {}
 #endif /* CONFIG_IOMMU_API */
 
 /**