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>

1 files changed, 10 insertions, 19 deletions

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 05c0fb2acbc4..b78671a8a914 100644
--- 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);
 }