From: Gautam Dawar <gautam.dawar@xilinx.com>
Date: Wed, 30 Mar 2022 23:33:49 +0530
Subject: vhost: support ASID in IOTLB API
Patch-mainline: v5.19-rc1
Git-commit: 91233ad711866f4e375742d84ef3ed6aab9daa96
References: jsc#PED-1549

This patches allows userspace to send ASID based IOTLB message to
vhost. This idea is to use the reserved u32 field in the existing V2
IOTLB message. Vhost device should advertise this capability via
VHOST_BACKEND_F_IOTLB_ASID backend feature.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Gautam Dawar <gdawar@xilinx.com>
Message-Id: <20220330180436.24644-10-gdawar@xilinx.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/vhost/vdpa.c             |    5 ++++-
 drivers/vhost/vhost.c            |   23 ++++++++++++++++++-----
 drivers/vhost/vhost.h            |    4 ++--
 include/uapi/linux/vhost_types.h |    6 +++++-
 4 files changed, 29 insertions(+), 9 deletions(-)

--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -870,7 +870,7 @@ static int vhost_vdpa_process_iotlb_upda
 				 msg->perm);
 }
 
-static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
+static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
 					struct vhost_iotlb_msg *msg)
 {
 	struct vhost_vdpa *v = container_of(dev, struct vhost_vdpa, vdev);
@@ -879,6 +879,9 @@ static int vhost_vdpa_process_iotlb_msg(
 	struct vhost_iotlb *iotlb = v->iotlb;
 	int r = 0;
 
+	if (asid != 0)
+		return -EINVAL;
+
 	mutex_lock(&dev->mutex);
 
 	r = vhost_dev_check_owner(dev);
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -468,7 +468,7 @@ void vhost_dev_init(struct vhost_dev *de
 		    struct vhost_virtqueue **vqs, int nvqs,
 		    int iov_limit, int weight, int byte_weight,
 		    bool use_worker,
-		    int (*msg_handler)(struct vhost_dev *dev,
+		    int (*msg_handler)(struct vhost_dev *dev, u32 asid,
 				       struct vhost_iotlb_msg *msg))
 {
 	struct vhost_virtqueue *vq;
@@ -1090,11 +1090,14 @@ static bool umem_access_ok(u64 uaddr, u6
 	return true;
 }
 
-static int vhost_process_iotlb_msg(struct vhost_dev *dev,
+static int vhost_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
 				   struct vhost_iotlb_msg *msg)
 {
 	int ret = 0;
 
+	if (asid != 0)
+		return -EINVAL;
+
 	mutex_lock(&dev->mutex);
 	vhost_dev_lock_vqs(dev);
 	switch (msg->type) {
@@ -1141,6 +1144,7 @@ ssize_t vhost_chr_write_iter(struct vhos
 	struct vhost_iotlb_msg msg;
 	size_t offset;
 	int type, ret;
+	u32 asid = 0;
 
 	ret = copy_from_iter(&type, sizeof(type), from);
 	if (ret != sizeof(type)) {
@@ -1156,7 +1160,16 @@ ssize_t vhost_chr_write_iter(struct vhos
 		offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
 		break;
 	case VHOST_IOTLB_MSG_V2:
-		offset = sizeof(__u32);
+		if (vhost_backend_has_feature(dev->vqs[0],
+					      VHOST_BACKEND_F_IOTLB_ASID)) {
+			ret = copy_from_iter(&asid, sizeof(asid), from);
+			if (ret != sizeof(asid)) {
+				ret = -EINVAL;
+				goto done;
+			}
+			offset = sizeof(__u16);
+		} else
+			offset = sizeof(__u32);
 		break;
 	default:
 		ret = -EINVAL;
@@ -1171,9 +1184,9 @@ ssize_t vhost_chr_write_iter(struct vhos
 	}
 
 	if (dev->msg_handler)
-		ret = dev->msg_handler(dev, &msg);
+		ret = dev->msg_handler(dev, asid, &msg);
 	else
-		ret = vhost_process_iotlb_msg(dev, &msg);
+		ret = vhost_process_iotlb_msg(dev, asid, &msg);
 	if (ret) {
 		ret = -EFAULT;
 		goto done;
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -161,7 +161,7 @@ struct vhost_dev {
 	int byte_weight;
 	u64 kcov_handle;
 	bool use_worker;
-	int (*msg_handler)(struct vhost_dev *dev,
+	int (*msg_handler)(struct vhost_dev *dev, u32 asid,
 			   struct vhost_iotlb_msg *msg);
 };
 
@@ -169,7 +169,7 @@ bool vhost_exceeds_weight(struct vhost_v
 void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs,
 		    int nvqs, int iov_limit, int weight, int byte_weight,
 		    bool use_worker,
-		    int (*msg_handler)(struct vhost_dev *dev,
+		    int (*msg_handler)(struct vhost_dev *dev, u32 asid,
 				       struct vhost_iotlb_msg *msg));
 long vhost_dev_set_owner(struct vhost_dev *dev);
 bool vhost_dev_has_owner(struct vhost_dev *dev);
--- a/include/uapi/linux/vhost_types.h
+++ b/include/uapi/linux/vhost_types.h
@@ -87,7 +87,7 @@ struct vhost_msg {
 
 struct vhost_msg_v2 {
 	__u32 type;
-	__u32 reserved;
+	__u32 asid;
 	union {
 		struct vhost_iotlb_msg iotlb;
 		__u8 padding[64];
@@ -157,5 +157,9 @@ struct vhost_vdpa_iova_range {
 #define VHOST_BACKEND_F_IOTLB_MSG_V2 0x1
 /* IOTLB can accept batching hints */
 #define VHOST_BACKEND_F_IOTLB_BATCH  0x2
+/* IOTLB can accept address space identifier through V2 type of IOTLB
+ * message
+ */
+#define VHOST_BACKEND_F_IOTLB_ASID  0x3
 
 #endif