This patch allows user space to request PASID allocation/free, e.g. when
serving the request from the guest.

PASIDs that are not freed by userspace are automatically freed when the
IOASID set is destroyed when process exits.

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>
Cc: Joerg Roedel <j...@8bytes.org>
Cc: Lu Baolu <baolu...@linux.intel.com>
Signed-off-by: Liu Yi L <yi.l....@intel.com>
Signed-off-by: Yi Sun <yi.y....@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com>
---
v4 -> v5:
*) address comments from Eric Auger.
*) the comments for the PASID_FREE request is addressed in patch 5/15 of
   this series.

v3 -> v4:
*) address comments from v3, except the below comment against the range
   of PASID_FREE request. needs more help on it.
    "> +if (req.range.min > req.range.max)

    Is it exploitable that a user can spin the kernel for a long time in
    the case of a free by calling this with [0, MAX_UINT] regardless of
    their actual allocations?"
    https://lore.kernel.org/linux-iommu/20200702151832.048b4...@x1.home/

v1 -> v2:
*) move the vfio_mm related code to be a seprate module
*) use a single structure for alloc/free, could support a range of PASIDs
*) fetch vfio_mm at group_attach time instead of at iommu driver open time
---
 drivers/vfio/Kconfig            |  1 +
 drivers/vfio/vfio_iommu_type1.c | 85 +++++++++++++++++++++++++++++++++++++++++
 drivers/vfio/vfio_pasid.c       | 10 +++++
 include/linux/vfio.h            |  6 +++
 include/uapi/linux/vfio.h       | 37 ++++++++++++++++++
 5 files changed, 139 insertions(+)

diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 3d8a108..95d90c6 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -2,6 +2,7 @@
 config VFIO_IOMMU_TYPE1
        tristate
        depends on VFIO
+       select VFIO_PASID if (X86)
        default n
 
 config VFIO_IOMMU_SPAPR_TCE
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index ed80104..55b4065 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -76,6 +76,7 @@ struct vfio_iommu {
        bool                            dirty_page_tracking;
        bool                            pinned_page_dirty_scope;
        struct iommu_nesting_info       *nesting_info;
+       struct vfio_mm                  *vmm;
 };
 
 struct vfio_domain {
@@ -1937,6 +1938,11 @@ static void vfio_iommu_iova_insert_copy(struct 
vfio_iommu *iommu,
 
 static void vfio_iommu_release_nesting_info(struct vfio_iommu *iommu)
 {
+       if (iommu->vmm) {
+               vfio_mm_put(iommu->vmm);
+               iommu->vmm = NULL;
+       }
+
        kfree(iommu->nesting_info);
        iommu->nesting_info = NULL;
 }
@@ -2071,6 +2077,26 @@ static int vfio_iommu_type1_attach_group(void 
*iommu_data,
                                            iommu->nesting_info);
                if (ret)
                        goto out_detach;
+
+               if (iommu->nesting_info->features &
+                                       IOMMU_NESTING_FEAT_SYSWIDE_PASID) {
+                       struct vfio_mm *vmm;
+                       int sid;
+
+                       vmm = vfio_mm_get_from_task(current);
+                       if (IS_ERR(vmm)) {
+                               ret = PTR_ERR(vmm);
+                               goto out_detach;
+                       }
+                       iommu->vmm = vmm;
+
+                       sid = vfio_mm_ioasid_sid(vmm);
+                       ret = iommu_domain_set_attr(domain->domain,
+                                                   DOMAIN_ATTR_IOASID_SID,
+                                                   &sid);
+                       if (ret)
+                               goto out_detach;
+               }
        }
 
        /* Get aperture info */
@@ -2855,6 +2881,63 @@ static int vfio_iommu_type1_dirty_pages(struct 
vfio_iommu *iommu,
        return -EINVAL;
 }
 
+static int vfio_iommu_type1_pasid_alloc(struct vfio_iommu *iommu,
+                                       unsigned int min,
+                                       unsigned int max)
+{
+       int ret = -EOPNOTSUPP;
+
+       mutex_lock(&iommu->lock);
+       if (iommu->vmm)
+               ret = vfio_pasid_alloc(iommu->vmm, min, max);
+       mutex_unlock(&iommu->lock);
+       return ret;
+}
+
+static int vfio_iommu_type1_pasid_free(struct vfio_iommu *iommu,
+                                      unsigned int min,
+                                      unsigned int max)
+{
+       int ret = -EOPNOTSUPP;
+
+       mutex_lock(&iommu->lock);
+       if (iommu->vmm) {
+               vfio_pasid_free_range(iommu->vmm, min, max);
+               ret = 0;
+       }
+       mutex_unlock(&iommu->lock);
+       return ret;
+}
+
+static int vfio_iommu_type1_pasid_request(struct vfio_iommu *iommu,
+                                         unsigned long arg)
+{
+       struct vfio_iommu_type1_pasid_request req;
+       unsigned long minsz;
+
+       minsz = offsetofend(struct vfio_iommu_type1_pasid_request, range);
+
+       if (copy_from_user(&req, (void __user *)arg, minsz))
+               return -EFAULT;
+
+       if (req.argsz < minsz || (req.flags & ~VFIO_PASID_REQUEST_MASK))
+               return -EINVAL;
+
+       if (req.range.min > req.range.max)
+               return -EINVAL;
+
+       switch (req.flags & VFIO_PASID_REQUEST_MASK) {
+       case VFIO_IOMMU_FLAG_ALLOC_PASID:
+               return vfio_iommu_type1_pasid_alloc(iommu,
+                                       req.range.min, req.range.max);
+       case VFIO_IOMMU_FLAG_FREE_PASID:
+               return vfio_iommu_type1_pasid_free(iommu,
+                                       req.range.min, req.range.max);
+       default:
+               return -EINVAL;
+       }
+}
+
 static long vfio_iommu_type1_ioctl(void *iommu_data,
                                   unsigned int cmd, unsigned long arg)
 {
@@ -2871,6 +2954,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
                return vfio_iommu_type1_unmap_dma(iommu, arg);
        case VFIO_IOMMU_DIRTY_PAGES:
                return vfio_iommu_type1_dirty_pages(iommu, arg);
+       case VFIO_IOMMU_PASID_REQUEST:
+               return vfio_iommu_type1_pasid_request(iommu, arg);
        default:
                return -ENOTTY;
        }
diff --git a/drivers/vfio/vfio_pasid.c b/drivers/vfio/vfio_pasid.c
index 66e6054e..ebec244 100644
--- a/drivers/vfio/vfio_pasid.c
+++ b/drivers/vfio/vfio_pasid.c
@@ -61,6 +61,7 @@ void vfio_mm_put(struct vfio_mm *vmm)
 {
        kref_put_mutex(&vmm->kref, vfio_mm_release, &vfio_mm_lock);
 }
+EXPORT_SYMBOL_GPL(vfio_mm_put);
 
 static void vfio_mm_get(struct vfio_mm *vmm)
 {
@@ -114,6 +115,13 @@ struct vfio_mm *vfio_mm_get_from_task(struct task_struct 
*task)
        mmput(mm);
        return vmm;
 }
+EXPORT_SYMBOL_GPL(vfio_mm_get_from_task);
+
+int vfio_mm_ioasid_sid(struct vfio_mm *vmm)
+{
+       return vmm->ioasid_sid;
+}
+EXPORT_SYMBOL_GPL(vfio_mm_ioasid_sid);
 
 /*
  * Find PASID within @min and @max
@@ -197,6 +205,7 @@ int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max)
 
        return pasid;
 }
+EXPORT_SYMBOL_GPL(vfio_pasid_alloc);
 
 void vfio_pasid_free_range(struct vfio_mm *vmm,
                           ioasid_t min, ioasid_t max)
@@ -213,6 +222,7 @@ void vfio_pasid_free_range(struct vfio_mm *vmm,
                vfio_remove_pasid(vmm, vid);
        mutex_unlock(&vmm->pasid_lock);
 }
+EXPORT_SYMBOL_GPL(vfio_pasid_free_range);
 
 static int __init vfio_pasid_init(void)
 {
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 31472a9..a111108 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -101,6 +101,7 @@ struct vfio_mm;
 #if IS_ENABLED(CONFIG_VFIO_PASID)
 extern struct vfio_mm *vfio_mm_get_from_task(struct task_struct *task);
 extern void vfio_mm_put(struct vfio_mm *vmm);
+int vfio_mm_ioasid_sid(struct vfio_mm *vmm);
 extern int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max);
 extern void vfio_pasid_free_range(struct vfio_mm *vmm,
                                  ioasid_t min, ioasid_t max);
@@ -114,6 +115,11 @@ static inline void vfio_mm_put(struct vfio_mm *vmm)
 {
 }
 
+static inline int vfio_mm_ioasid_sid(struct vfio_mm *vmm)
+{
+       return -ENOTTY;
+}
+
 static inline int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max)
 {
        return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 46a78af..96a115f 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1172,6 +1172,43 @@ struct vfio_iommu_type1_dirty_bitmap_get {
 
 #define VFIO_IOMMU_DIRTY_PAGES             _IO(VFIO_TYPE, VFIO_BASE + 17)
 
+/**
+ * VFIO_IOMMU_PASID_REQUEST - _IOWR(VFIO_TYPE, VFIO_BASE + 18,
+ *                             struct vfio_iommu_type1_pasid_request)
+ *
+ * PASID (Processor Address Space ID) is a PCIe concept for tagging
+ * address spaces in DMA requests. When system-wide PASID allocation
+ * is required by underlying iommu driver (e.g. Intel VT-d), this
+ * provides an interface for userspace to request pasid alloc/free
+ * for its assigned devices. Userspace should check the availability
+ * of this API by checking VFIO_IOMMU_TYPE1_INFO_CAP_NESTING through
+ * VFIO_IOMMU_GET_INFO.
+ *
+ * @flags=VFIO_IOMMU_FLAG_ALLOC_PASID, allocate a single PASID within @range.
+ * @flags=VFIO_IOMMU_FLAG_FREE_PASID, free the PASIDs within @range.
+ * @range is [min, max], which means both @min and @max are inclusive.
+ * ALLOC_PASID and FREE_PASID are mutually exclusive.
+ *
+ * returns: allocated PASID value on success, -errno on failure for
+ *          ALLOC_PASID;
+ *          0 for FREE_PASID operation;
+ */
+struct vfio_iommu_type1_pasid_request {
+       __u32   argsz;
+#define VFIO_IOMMU_FLAG_ALLOC_PASID    (1 << 0)
+#define VFIO_IOMMU_FLAG_FREE_PASID     (1 << 1)
+       __u32   flags;
+       struct {
+               __u32   min;
+               __u32   max;
+       } range;
+};
+
+#define VFIO_PASID_REQUEST_MASK        (VFIO_IOMMU_FLAG_ALLOC_PASID | \
+                                        VFIO_IOMMU_FLAG_FREE_PASID)
+
+#define VFIO_IOMMU_PASID_REQUEST       _IO(VFIO_TYPE, VFIO_BASE + 18)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
2.7.4

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