From: Liu Yi L <yi.l....@intel.com>

This patch adds a module option to make the PASID quota tunable by
administrator.

TODO: needs to think more on how to  make the tuning to be per-process.

Previous discussions:
https://patchwork.kernel.org/patch/11209429/

Cc: Kevin Tian <kevin.t...@intel.com>
CC: Jacob Pan <jacob.jun....@linux.intel.com>
Cc: Alex Williamson <alex.william...@redhat.com>
Cc: Eric Auger <eric.au...@redhat.com>
Cc: Jean-Philippe Brucker <jean-phili...@linaro.org>
Signed-off-by: Liu Yi L <yi.l....@intel.com>
---
 drivers/vfio/vfio.c             | 8 +++++++-
 drivers/vfio/vfio_iommu_type1.c | 7 ++++++-
 include/linux/vfio.h            | 3 ++-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index d13b483..020a792 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -2217,13 +2217,19 @@ struct vfio_mm *vfio_mm_get_from_task(struct 
task_struct *task)
 }
 EXPORT_SYMBOL_GPL(vfio_mm_get_from_task);
 
-int vfio_mm_pasid_alloc(struct vfio_mm *vmm, int min, int max)
+int vfio_mm_pasid_alloc(struct vfio_mm *vmm, int quota, int min, int max)
 {
        ioasid_t pasid;
        int ret = -ENOSPC;
 
        mutex_lock(&vmm->pasid_lock);
 
+       /* update quota as it is tunable by admin */
+       if (vmm->pasid_quota != quota) {
+               vmm->pasid_quota = quota;
+               ioasid_adjust_set(vmm->ioasid_sid, quota);
+       }
+
        pasid = ioasid_alloc(vmm->ioasid_sid, min, max, NULL);
        if (pasid == INVALID_IOASID) {
                ret = -ENOSPC;
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 331ceee..e40afc0 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -60,6 +60,11 @@ module_param_named(dma_entry_limit, dma_entry_limit, uint, 
0644);
 MODULE_PARM_DESC(dma_entry_limit,
                 "Maximum number of user DMA mappings per container (65535).");
 
+static int pasid_quota = VFIO_DEFAULT_PASID_QUOTA;
+module_param_named(pasid_quota, pasid_quota, uint, 0644);
+MODULE_PARM_DESC(pasid_quota,
+                "Quota of user owned PASIDs per vfio-based application 
(1000).");
+
 struct vfio_iommu {
        struct list_head        domain_list;
        struct list_head        iova_list;
@@ -2200,7 +2205,7 @@ static int vfio_iommu_type1_pasid_alloc(struct vfio_iommu 
*iommu,
                goto out_unlock;
        }
        if (vmm)
-               ret = vfio_mm_pasid_alloc(vmm, min, max);
+               ret = vfio_mm_pasid_alloc(vmm, pasid_quota, min, max);
        else
                ret = -EINVAL;
 out_unlock:
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 75f9f7f1..af2ef78 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -106,7 +106,8 @@ struct vfio_mm {
 
 extern struct vfio_mm *vfio_mm_get_from_task(struct task_struct *task);
 extern void vfio_mm_put(struct vfio_mm *vmm);
-extern int vfio_mm_pasid_alloc(struct vfio_mm *vmm, int min, int max);
+extern int vfio_mm_pasid_alloc(struct vfio_mm *vmm,
+                               int quota, int min, int max);
 extern int vfio_mm_pasid_free(struct vfio_mm *vmm, ioasid_t pasid);
 
 /*
-- 
2.7.4

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