[RFC v1 4/4] vfio/type1: bind guest pasid (guest page tables) to host

["Liu, Yi L" <yi.l.liu@intel.com>]

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

This patch adds vfio support to bind guest translation structure
to host iommu. VFIO exposes iommu programming capability to user-
space. Guest is a user-space application in host under KVM solution.
For SVA usage in Virtual Machine, guest owns GVA->GPA translation
structure. And this part should be passdown to host to enable nested
translation (or say two stage translation). This patch reuses the
VFIO_IOMMU_BIND proposal from Jean-Philippe Brucker, and adds new
bind type for binding guest owned translation structure to host.

*) Add two new ioctls for VFIO containers.

  - VFIO_IOMMU_BIND: for bind request from userspace, it could be
                   bind a process to a pasid or bind a guest pasid
                   to a device, this is indicated by type
  - VFIO_IOMMU_UNBIND: for unbind request from userspace, it could be
                   unbind a process to a pasid or unbind a guest pasid
                   to a device, also indicated by type
  - Bind type:
	VFIO_IOMMU_BIND_PROCESS: user-space request to bind a process
                   to a device
	VFIO_IOMMU_BIND_GUEST_PASID: bind guest owned translation
                   structure to host iommu. e.g. guest page table

*) Code logic in vfio_iommu_type1_ioctl() to handle VFIO_IOMMU_BIND/UNBIND

Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 drivers/vfio/vfio_iommu_type1.c | 151 ++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       |  56 +++++++++++++++
 2 files changed, 207 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index d5e0c01..57826ed 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -1920,6 +1920,119 @@ static int vfio_iommu_type1_pasid_free(struct vfio_iommu *iommu, int pasid)
 	return ret;
 }
 
+static int vfio_bind_gpasid_fn(struct device *dev, void *data)
+{
+	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+	struct vfio_iommu_type1_bind_guest_pasid *guest_bind = data;
+
+	return iommu_sva_bind_gpasid(domain, dev, &guest_bind->bind_data);
+}
+
+static int vfio_unbind_gpasid_fn(struct device *dev, void *data)
+{
+	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+	struct vfio_iommu_type1_bind_guest_pasid *guest_bind = data;
+
+	return iommu_sva_unbind_gpasid(domain, dev,
+					guest_bind->bind_data.hpasid);
+}
+
+/*
+ * unbind specific gpasid, caller of this function requires hold
+ * vfio_iommu->lock
+ */
+static long vfio_iommu_type1_do_guest_unbind(struct vfio_iommu *iommu,
+		  struct vfio_iommu_type1_bind_guest_pasid *guest_bind)
+{
+	struct vfio_domain *domain;
+	struct vfio_group *group;
+	int ret = 0;
+
+	if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	list_for_each_entry(domain, &iommu->domain_list, next) {
+		list_for_each_entry(group, &domain->group_list, next) {
+			ret = iommu_group_for_each_dev(group->iommu_group,
+			   guest_bind, vfio_unbind_gpasid_fn);
+			if (ret)
+				goto out;
+		}
+	}
+
+	return 0;
+
+out:
+	return ret;
+}
+
+static long vfio_iommu_type1_bind_gpasid(struct vfio_iommu *iommu,
+					    void __user *arg,
+					    struct vfio_iommu_type1_bind *bind)
+{
+	struct vfio_iommu_type1_bind_guest_pasid guest_bind;
+	struct vfio_domain *domain;
+	struct vfio_group *group;
+	unsigned long minsz;
+	int ret = 0;
+
+	minsz = sizeof(*bind) + sizeof(guest_bind);
+	if (bind->argsz < minsz)
+		return -EINVAL;
+
+	if (copy_from_user(&guest_bind, arg, sizeof(guest_bind)))
+		return -EFAULT;
+
+	mutex_lock(&iommu->lock);
+	if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	list_for_each_entry(domain, &iommu->domain_list, next) {
+		list_for_each_entry(group, &domain->group_list, next) {
+			ret = iommu_group_for_each_dev(group->iommu_group,
+			   &guest_bind, vfio_bind_gpasid_fn);
+			if (ret)
+				goto out_unbind;
+		}
+	}
+
+	mutex_unlock(&iommu->lock);
+	return 0;
+
+out_unbind:
+	/* Undo all binds that already succeeded */
+	vfio_iommu_type1_do_guest_unbind(iommu, &guest_bind);
+
+out_unlock:
+	mutex_unlock(&iommu->lock);
+	return ret;
+}
+
+static long vfio_iommu_type1_unbind_gpasid(struct vfio_iommu *iommu,
+					    void __user *arg,
+					    struct vfio_iommu_type1_bind *bind)
+{
+	struct vfio_iommu_type1_bind_guest_pasid guest_bind;
+	unsigned long minsz;
+	int ret = 0;
+
+	minsz = sizeof(*bind) + sizeof(guest_bind);
+	if (bind->argsz < minsz)
+		return -EINVAL;
+
+	if (copy_from_user(&guest_bind, arg, sizeof(guest_bind)))
+		return -EFAULT;
+
+	mutex_lock(&iommu->lock);
+	ret = vfio_iommu_type1_do_guest_unbind(iommu, &guest_bind);
+	mutex_unlock(&iommu->lock);
+	return ret;
+}
+
 static long vfio_iommu_type1_ioctl(void *iommu_data,
 				   unsigned int cmd, unsigned long arg)
 {
@@ -2061,6 +2174,44 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 		default:
 			return -EINVAL;
 		}
+
+	} else if (cmd == VFIO_IOMMU_BIND) {
+		struct vfio_iommu_type1_bind bind;
+
+		minsz = offsetofend(struct vfio_iommu_type1_bind, bind_type);
+
+		if (copy_from_user(&bind, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (bind.argsz < minsz)
+			return -EINVAL;
+
+		switch (bind.bind_type) {
+		case VFIO_IOMMU_BIND_GUEST_PASID:
+			return vfio_iommu_type1_bind_gpasid(iommu,
+					(void __user *)(arg + minsz), &bind);
+		default:
+			return -EINVAL;
+		}
+
+	} else if (cmd == VFIO_IOMMU_UNBIND) {
+		struct vfio_iommu_type1_bind bind;
+
+		minsz = offsetofend(struct vfio_iommu_type1_bind, bind_type);
+
+		if (copy_from_user(&bind, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (bind.argsz < minsz)
+			return -EINVAL;
+
+		switch (bind.bind_type) {
+		case VFIO_IOMMU_BIND_GUEST_PASID:
+			return vfio_iommu_type1_unbind_gpasid(iommu,
+					(void __user *)(arg + minsz), &bind);
+		default:
+			return -EINVAL;
+		}
 	}
 
 	return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index af03c9f..4167bbd 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -823,6 +823,62 @@ struct vfio_iommu_type1_pasid_request {
  */
 #define VFIO_IOMMU_PASID_REQUEST	_IO(VFIO_TYPE, VFIO_BASE + 27)
 
+/*
+ * In guest use of SVA, the first level page tables is managed by the guest.
+ * we can either bind guest PASID table or explicitly bind a PASID with guest
+ * page table.
+ */
+struct vfio_iommu_type1_bind_guest_pasid {
+	struct gpasid_bind_data bind_data;
+};
+
+enum vfio_iommu_bind_type {
+	VFIO_IOMMU_BIND_PROCESS,
+	VFIO_IOMMU_BIND_GUEST_PASID,
+};
+
+/*
+ * Supported types:
+ *     - VFIO_IOMMU_BIND_PROCESS: bind native process, which takes
+ *                      vfio_iommu_type1_bind_process in data.
+ *     - VFIO_IOMMU_BIND_GUEST_PASID: bind guest pasid, which invoked
+ *                      by guest process binding, it takes
+ *                      vfio_iommu_type1_bind_guest_pasid in data.
+ */
+struct vfio_iommu_type1_bind {
+	__u32				argsz;
+	enum vfio_iommu_bind_type	bind_type;
+	__u8				data[];
+};
+
+/*
+ * VFIO_IOMMU_BIND - _IOWR(VFIO_TYPE, VFIO_BASE + 28, struct vfio_iommu_bind)
+ *
+ * Manage address spaces of devices in this container. Initially a TYPE1
+ * container can only have one address space, managed with
+ * VFIO_IOMMU_MAP/UNMAP_DMA.
+ *
+ * An IOMMU of type VFIO_TYPE1_NESTING_IOMMU can be managed by both MAP/UNMAP
+ * and BIND ioctls at the same time. MAP/UNMAP acts on the stage-2 (host) page
+ * tables, and BIND manages the stage-1 (guest) page tables. Other types of
+ * IOMMU may allow MAP/UNMAP and BIND to coexist, where MAP/UNMAP controls
+ * non-PASID traffic and BIND controls PASID traffic. But this depends on the
+ * underlying IOMMU architecture and isn't guaranteed.
+ *
+ * Availability of this feature depends on the device, its bus, the underlying
+ * IOMMU and the CPU architecture.
+ *
+ * returns: 0 on success, -errno on failure.
+ */
+#define VFIO_IOMMU_BIND		_IO(VFIO_TYPE, VFIO_BASE + 28)
+
+/*
+ * VFIO_IOMMU_UNBIND - _IOWR(VFIO_TYPE, VFIO_BASE + 29, struct vfio_iommu_bind)
+ *
+ * Undo what was done by the corresponding VFIO_IOMMU_BIND ioctl.
+ */
+#define VFIO_IOMMU_UNBIND	_IO(VFIO_TYPE, VFIO_BASE + 29)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
2.7.4