[PATCH v7 4/7] iommu/sva: Stop using ioasid_set for SVA

Jacob Pan
2023-03-20T19:05:33Z

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>
---
v5:
- Put removing iommu_sva_find() to a separate patch (Kevin)
- Make pasid allocation range to be inclusive (Tina)
- Simplified return code handling (Baolu)
v4:
- Keep GFP_ATOMIC flag for PASID allocation, will changed to
GFP_KERNEL in a separate patch.
---
drivers/iommu/iommu-sva.c | 41 +++++++++++++--------------------------
drivers/iommu/iommu-sva.h | 2 --
2 files changed, 14 insertions(+), 29 deletions(-)

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 4f357ef14f04..48e8a15ddc9b 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -9,47 +9,34 @@
#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)
+/* 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)
{
int ret = 0;
- ioasid_t pasid;

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

mutex_lock(&iommu_sva_lock);
/* Is a PASID already associated with this mm? */
if (pasid_valid(mm->pasid)) {
- if (mm->pasid < min || mm->pasid >= max)
+ if (mm->pasid < min || mm->pasid > max)
ret = -EOVERFLOW;
goto out;
}

- pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
- if (!pasid_valid(pasid))
- ret = -ENOMEM;
- else
- mm->pasid = pasid;
+ ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_ATOMIC);
+ if (ret < 0)
+ goto out;
+ mm->pasid = ret;
+ ret = 0;
out:
mutex_unlock(&iommu_sva_lock);
return ret;
}
-EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid);

/**
* iommu_sva_bind_device() - Bind a process address space to a device
@@ -221,8 +208,8 @@ iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)

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 102eae1817a2..c22d0174ad61 100644
--- a/drivers/iommu/iommu-sva.h
+++ b/drivers/iommu/iommu-sva.h
@@ -8,8 +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);
-
/* I/O Page fault */
struct device;
struct iommu_fault;
--
2.25.1