Nesting translation allows two-levels/stages page tables, with 1st level
for guest translations (e.g. GVA->GPA), 2nd level for host translations
(e.g. GPA->HPA). This patch adds interface for binding guest page tables
to a PASID. This PASID must have been allocated to user space before the
binding request.

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: Jean-Philippe Brucker <jean-phili...@linaro.com>
Signed-off-by: Liu Yi L <yi.l....@intel.com>
Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com>
---
v3 -> v4:
*) address comments from Alex on v3

v2 -> v3:
*) use __iommu_sva_unbind_gpasid() for unbind call issued by VFIO
   
https://lore.kernel.org/linux-iommu/1592931837-58223-6-git-send-email-jacob.jun....@linux.intel.com/

v1 -> v2:
*) rename subject from "vfio/type1: Bind guest page tables to host"
*) remove VFIO_IOMMU_BIND, introduce VFIO_IOMMU_NESTING_OP to support bind/
   unbind guet page table
*) replaced vfio_iommu_for_each_dev() with a group level loop since this
   series enforces one group per container w/ nesting type as start.
*) rename vfio_bind/unbind_gpasid_fn() to vfio_dev_bind/unbind_gpasid_fn()
*) vfio_dev_unbind_gpasid() always successful
*) use vfio_mm->pasid_lock to avoid race between PASID free and page table
   bind/unbind
---
 drivers/vfio/vfio_iommu_type1.c | 166 ++++++++++++++++++++++++++++++++++++++++
 drivers/vfio/vfio_pasid.c       |  26 +++++++
 include/linux/vfio.h            |  20 +++++
 include/uapi/linux/vfio.h       |  31 ++++++++
 4 files changed, 243 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 55b4065..f0f21ff 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -149,6 +149,30 @@ struct vfio_regions {
 #define DIRTY_BITMAP_PAGES_MAX  ((u64)INT_MAX)
 #define DIRTY_BITMAP_SIZE_MAX   DIRTY_BITMAP_BYTES(DIRTY_BITMAP_PAGES_MAX)
 
+struct domain_capsule {
+       struct vfio_group *group;
+       struct iommu_domain *domain;
+       void *data;
+};
+
+/* iommu->lock must be held */
+static struct vfio_group *vfio_find_nesting_group(struct vfio_iommu *iommu)
+{
+       struct vfio_domain *d;
+       struct vfio_group *group = NULL;
+
+       if (!iommu->nesting_info)
+               return NULL;
+
+       /* only support singleton container with nesting type */
+       list_for_each_entry(d, &iommu->domain_list, next) {
+               list_for_each_entry(group, &d->group_list, next) {
+                       break;
+               }
+       }
+       return group;
+}
+
 static int put_pfn(unsigned long pfn, int prot);
 
 static struct vfio_group *vfio_iommu_find_iommu_group(struct vfio_iommu *iommu,
@@ -2349,6 +2373,48 @@ static int vfio_iommu_resv_refresh(struct vfio_iommu 
*iommu,
        return ret;
 }
 
+static int vfio_dev_bind_gpasid_fn(struct device *dev, void *data)
+{
+       struct domain_capsule *dc = (struct domain_capsule *)data;
+       unsigned long arg = *(unsigned long *)dc->data;
+
+       return iommu_sva_bind_gpasid(dc->domain, dev, (void __user *)arg);
+}
+
+static int vfio_dev_unbind_gpasid_fn(struct device *dev, void *data)
+{
+       struct domain_capsule *dc = (struct domain_capsule *)data;
+       unsigned long arg = *(unsigned long *)dc->data;
+
+       iommu_sva_unbind_gpasid(dc->domain, dev, (void __user *)arg);
+       return 0;
+}
+
+static int __vfio_dev_unbind_gpasid_fn(struct device *dev, void *data)
+{
+       struct domain_capsule *dc = (struct domain_capsule *)data;
+       struct iommu_gpasid_bind_data *unbind_data =
+                               (struct iommu_gpasid_bind_data *)dc->data;
+
+       __iommu_sva_unbind_gpasid(dc->domain, dev, unbind_data);
+       return 0;
+}
+
+static void vfio_group_unbind_gpasid_fn(ioasid_t pasid, void *data)
+{
+       struct domain_capsule *dc = (struct domain_capsule *)data;
+       struct iommu_gpasid_bind_data unbind_data;
+
+       unbind_data.argsz = offsetof(struct iommu_gpasid_bind_data, vendor);
+       unbind_data.flags = 0;
+       unbind_data.hpasid = pasid;
+
+       dc->data = &unbind_data;
+
+       iommu_group_for_each_dev(dc->group->iommu_group,
+                                dc, __vfio_dev_unbind_gpasid_fn);
+}
+
 static void vfio_iommu_type1_detach_group(void *iommu_data,
                                          struct iommu_group *iommu_group)
 {
@@ -2392,6 +2458,21 @@ static void vfio_iommu_type1_detach_group(void 
*iommu_data,
                if (!group)
                        continue;
 
+               if (iommu->nesting_info && iommu->vmm &&
+                   (iommu->nesting_info->features &
+                                       IOMMU_NESTING_FEAT_BIND_PGTBL)) {
+                       struct domain_capsule dc = { .group = group,
+                                                    .domain = domain->domain,
+                                                    .data = NULL };
+
+                       /*
+                        * Unbind page tables bound with system wide PASIDs
+                        * which are allocated to user space.
+                        */
+                       vfio_mm_for_each_pasid(iommu->vmm, &dc,
+                                              vfio_group_unbind_gpasid_fn);
+               }
+
                vfio_iommu_detach_group(domain, group);
                update_dirty_scope = !group->pinned_page_dirty_scope;
                list_del(&group->next);
@@ -2938,6 +3019,89 @@ static int vfio_iommu_type1_pasid_request(struct 
vfio_iommu *iommu,
        }
 }
 
+static long vfio_iommu_handle_pgtbl_op(struct vfio_iommu *iommu,
+                                      bool is_bind, unsigned long arg)
+{
+       struct iommu_nesting_info *info;
+       struct domain_capsule dc = { .data = &arg };
+       struct vfio_group *group;
+       struct vfio_domain *domain;
+       int ret;
+
+       mutex_lock(&iommu->lock);
+
+       info = iommu->nesting_info;
+       if (!info || !(info->features & IOMMU_NESTING_FEAT_BIND_PGTBL)) {
+               ret = -EOPNOTSUPP;
+               goto out_unlock_iommu;
+       }
+
+       if (!iommu->vmm) {
+               ret = -EINVAL;
+               goto out_unlock_iommu;
+       }
+
+       group = vfio_find_nesting_group(iommu);
+       if (!group) {
+               ret = -EINVAL;
+               goto out_unlock_iommu;
+       }
+
+       domain = list_first_entry(&iommu->domain_list,
+                                 struct vfio_domain, next);
+       dc.group = group;
+       dc.domain = domain->domain;
+
+       /* Avoid race with other containers within the same process */
+       vfio_mm_pasid_lock(iommu->vmm);
+
+       if (is_bind) {
+               ret = iommu_group_for_each_dev(group->iommu_group, &dc,
+                                              vfio_dev_bind_gpasid_fn);
+               if (ret)
+                       iommu_group_for_each_dev(group->iommu_group, &dc,
+                                                vfio_dev_unbind_gpasid_fn);
+       } else {
+               iommu_group_for_each_dev(group->iommu_group,
+                                        &dc, vfio_dev_unbind_gpasid_fn);
+               ret = 0;
+       }
+
+       vfio_mm_pasid_unlock(iommu->vmm);
+out_unlock_iommu:
+       mutex_unlock(&iommu->lock);
+       return ret;
+}
+
+static long vfio_iommu_type1_nesting_op(struct vfio_iommu *iommu,
+                                       unsigned long arg)
+{
+       struct vfio_iommu_type1_nesting_op hdr;
+       unsigned int minsz;
+       int ret;
+
+       minsz = offsetofend(struct vfio_iommu_type1_nesting_op, flags);
+
+       if (copy_from_user(&hdr, (void __user *)arg, minsz))
+               return -EFAULT;
+
+       if (hdr.argsz < minsz || hdr.flags & ~VFIO_NESTING_OP_MASK)
+               return -EINVAL;
+
+       switch (hdr.flags & VFIO_NESTING_OP_MASK) {
+       case VFIO_IOMMU_NESTING_OP_BIND_PGTBL:
+               ret = vfio_iommu_handle_pgtbl_op(iommu, true, arg + minsz);
+               break;
+       case VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL:
+               ret = vfio_iommu_handle_pgtbl_op(iommu, false, arg + minsz);
+               break;
+       default:
+               ret = -EINVAL;
+       }
+
+       return ret;
+}
+
 static long vfio_iommu_type1_ioctl(void *iommu_data,
                                   unsigned int cmd, unsigned long arg)
 {
@@ -2956,6 +3120,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
                return vfio_iommu_type1_dirty_pages(iommu, arg);
        case VFIO_IOMMU_PASID_REQUEST:
                return vfio_iommu_type1_pasid_request(iommu, arg);
+       case VFIO_IOMMU_NESTING_OP:
+               return vfio_iommu_type1_nesting_op(iommu, arg);
        default:
                return -ENOTTY;
        }
diff --git a/drivers/vfio/vfio_pasid.c b/drivers/vfio/vfio_pasid.c
index ebec244..ecabaaa 100644
--- a/drivers/vfio/vfio_pasid.c
+++ b/drivers/vfio/vfio_pasid.c
@@ -216,6 +216,8 @@ void vfio_pasid_free_range(struct vfio_mm *vmm,
         * IOASID core will notify PASID users (e.g. IOMMU driver) to
         * teardown necessary structures depending on the to-be-freed
         * PASID.
+        * Hold pasid_lock also avoids race with PASID usages like bind/
+        * unbind page tables to requested PASID.
         */
        mutex_lock(&vmm->pasid_lock);
        while ((vid = vfio_find_pasid(vmm, min, max)) != NULL)
@@ -224,6 +226,30 @@ void vfio_pasid_free_range(struct vfio_mm *vmm,
 }
 EXPORT_SYMBOL_GPL(vfio_pasid_free_range);
 
+int vfio_mm_for_each_pasid(struct vfio_mm *vmm, void *data,
+                          void (*fn)(ioasid_t id, void *data))
+{
+       int ret;
+
+       mutex_lock(&vmm->pasid_lock);
+       ret = ioasid_set_for_each_ioasid(vmm->ioasid_sid, fn, data);
+       mutex_unlock(&vmm->pasid_lock);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(vfio_mm_for_each_pasid);
+
+void vfio_mm_pasid_lock(struct vfio_mm *vmm)
+{
+       mutex_lock(&vmm->pasid_lock);
+}
+EXPORT_SYMBOL_GPL(vfio_mm_pasid_lock);
+
+void vfio_mm_pasid_unlock(struct vfio_mm *vmm)
+{
+       mutex_unlock(&vmm->pasid_lock);
+}
+EXPORT_SYMBOL_GPL(vfio_mm_pasid_unlock);
+
 static int __init vfio_pasid_init(void)
 {
        mutex_init(&vfio_mm_lock);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index a111108..2bc8347 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -105,6 +105,11 @@ 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);
+extern int vfio_mm_for_each_pasid(struct vfio_mm *vmm, void *data,
+                                 void (*fn)(ioasid_t id, void *data));
+extern void vfio_mm_pasid_lock(struct vfio_mm *vmm);
+extern void vfio_mm_pasid_unlock(struct vfio_mm *vmm);
+
 #else
 static inline struct vfio_mm *vfio_mm_get_from_task(struct task_struct *task)
 {
@@ -129,6 +134,21 @@ static inline void vfio_pasid_free_range(struct vfio_mm 
*vmm,
                                          ioasid_t min, ioasid_t max)
 {
 }
+
+static inline int vfio_mm_for_each_pasid(struct vfio_mm *vmm, void *data,
+                                        void (*fn)(ioasid_t id, void *data))
+{
+       return -ENOTTY;
+}
+
+static inline void vfio_mm_pasid_lock(struct vfio_mm *vmm)
+{
+}
+
+static inline void vfio_mm_pasid_unlock(struct vfio_mm *vmm)
+{
+}
+
 #endif /* CONFIG_VFIO_PASID */
 
 /*
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 96a115f..a8ad786 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1209,6 +1209,37 @@ struct vfio_iommu_type1_pasid_request {
 
 #define VFIO_IOMMU_PASID_REQUEST       _IO(VFIO_TYPE, VFIO_BASE + 18)
 
+/**
+ * VFIO_IOMMU_NESTING_OP - _IOW(VFIO_TYPE, VFIO_BASE + 19,
+ *                             struct vfio_iommu_type1_nesting_op)
+ *
+ * This interface allows user space to utilize the nesting IOMMU
+ * capabilities as reported in VFIO_IOMMU_TYPE1_INFO_CAP_NESTING
+ * cap through VFIO_IOMMU_GET_INFO.
+ *
+ * @data[] types defined for each op:
+ * +=================+===============================================+
+ * | NESTING OP      |      @data[]                                  |
+ * +=================+===============================================+
+ * | BIND_PGTBL      |      struct iommu_gpasid_bind_data            |
+ * +-----------------+-----------------------------------------------+
+ * | UNBIND_PGTBL    |      struct iommu_gpasid_bind_data            |
+ * +-----------------+-----------------------------------------------+
+ *
+ * returns: 0 on success, -errno on failure.
+ */
+struct vfio_iommu_type1_nesting_op {
+       __u32   argsz;
+       __u32   flags;
+#define VFIO_NESTING_OP_MASK   (0xffff) /* lower 16-bits for op */
+       __u8    data[];
+};
+
+#define VFIO_IOMMU_NESTING_OP_BIND_PGTBL       (0)
+#define VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL     (1)
+
+#define VFIO_IOMMU_NESTING_OP          _IO(VFIO_TYPE, VFIO_BASE + 19)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
2.7.4

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