[PATCH v3 3/5] iommu/sva: Stop using ioasid_set for SVA

Jacob Pan
2023-02-16T23:56:30Z

From: Jason Gunthorpe <jgg@nvidia.com>

Instead SVA drivers can use a simple global IDA to allocate PASIDs for
each mm_struct.

Future work would be to allow drivers using the SVA APIs to reserve global
PASIDs from this IDA for their internal use, eg with the DMA API PASID
support.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
drivers/iommu/iommu-sva.c | 62 ++++++++++-----------------------------
drivers/iommu/iommu-sva.h | 3 --
2 files changed, 15 insertions(+), 50 deletions(-)

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index a3ee258936f0..17821ad5bf9b 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -9,26 +9,13 @@
#include "iommu-sva.h"

static DEFINE_MUTEX(iommu_sva_lock);
-static DECLARE_IOASID_SET(iommu_sva_pasid);
+static DEFINE_IDA(iommu_global_pasid_ida);

-/**
- * iommu_sva_alloc_pasid - Allocate a PASID for the mm
- * @mm: the mm
- * @min: minimum PASID value (inclusive)
- * @max: maximum PASID value (inclusive)
- *
- * 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 will be available for the lifetime of the mm.
- *
- * Returns 0 on success and < 0 on error.
- */
-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, ioasid_t min, ioasid_t max)
{
- int ret = 0;
- ioasid_t pasid;
+ int ret;

- if (min == INVALID_IOASID || max == INVALID_IOASID ||
+ if (min == IOMMU_PASID_INVALID || max == IOMMU_PASID_INVALID ||
min == 0 || max < min)
return -EINVAL;

@@ -37,39 +24,20 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
if (pasid_valid(mm->pasid)) {
if (mm->pasid < min || mm->pasid >= max)
ret = -EOVERFLOW;
+ else
+ ret = 0;
goto out;
}

- pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
- if (!pasid_valid(pasid))
- ret = -ENOMEM;
- else
- mm_pasid_set(mm, pasid);
+ ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL);
+ if (ret < min)
+ goto out;
+ mm_pasid_set(mm, ret);
+ ret = 0;
out:
mutex_unlock(&iommu_sva_lock);
return ret;
}
-EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid);
-
-/* ioasid_find getter() requires a void * argument */
-static bool __mmget_not_zero(void *mm)
-{
- return mmget_not_zero(mm);
-}
-
-/**
- * iommu_sva_find() - Find mm associated to the given PASID
- * @pasid: Process Address Space ID assigned to the mm
- *
- * On success a reference to the mm is taken, and must be released with mmput().
- *
- * Returns the mm corresponding to this PASID, or an error if not found.
- */
-struct mm_struct *iommu_sva_find(ioasid_t pasid)
-{
- return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
-}
-EXPORT_SYMBOL_GPL(iommu_sva_find);

void mm_pasid_init(struct mm_struct *mm)
{
@@ -84,10 +52,10 @@ void mm_pasid_set(struct mm_struct *mm, u32 pasid)

void mm_pasid_drop(struct mm_struct *mm)
{
- if (pasid_valid(mm->pasid)) {
- ioasid_free(mm->pasid);
- mm->pasid = INVALID_IOASID;
- }
+ if (likely(!pasid_valid(mm->pasid)))
+ return;
+
+ ida_free(&iommu_global_pasid_ida, mm->pasid);
}

/**
diff --git a/drivers/iommu/iommu-sva.h b/drivers/iommu/iommu-sva.h
index 7215a761b962..c22d0174ad61 100644
--- a/drivers/iommu/iommu-sva.h
+++ b/drivers/iommu/iommu-sva.h
@@ -8,9 +8,6 @@
#include <linux/ioasid.h>
#include <linux/mm_types.h>

-int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max);
-struct mm_struct *iommu_sva_find(ioasid_t pasid);
-
/* I/O Page fault */
struct device;
struct iommu_fault;
--
2.25.1