From 58acdab17ec00ab76105ab92a51c5ba4dec3df5a Mon Sep 17 00:00:00 2001
From: Si-Wei Liu <si-wei.liu@oracle.com>
Date: Fri, 6 May 2022 19:28:17 -0700
Subject: [PATCH 13/16] vhost-vdpa: change name and polarity for
 vhost_vdpa_one_time_request()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

RH-Author: Jason Wang <jasowang@redhat.com>
RH-MergeRequest: 98: Multiqueue fixes for vhost-vDPA
RH-Commit: [6/7] 7029778f463a136ff412c63b86b6953390e47bf8 (jasowang/qemu-kvm-cs)
RH-Bugzilla: 2070804
RH-Acked-by: Eugenio Pérez <eperezma@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
RH-Acked-by: Cindy Lu <lulu@redhat.com>

The name vhost_vdpa_one_time_request() was confusing. No
matter whatever it returns, its typical occurrence had
always been at requests that only need to be applied once.
And the name didn't suggest what it actually checks for.
Change it to vhost_vdpa_first_dev() with polarity flipped
for better readibility of code. That way it is able to
reflect what the check is really about.

This call is applicable to request which performs operation
only once, before queues are set up, and usually at the beginning
of the caller function. Document the requirement for it in place.

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Message-Id: <1651890498-24478-7-git-send-email-si-wei.liu@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
(cherry picked from commit d71b0609fc04217e28d17009f04d74b08be6f466)
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/virtio/vhost-vdpa.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 6e3dbd9e89..33dcaa135e 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -366,11 +366,18 @@ static void vhost_vdpa_get_iova_range(struct vhost_vdpa *v)
                                     v->iova_range.last);
 }
 
-static bool vhost_vdpa_one_time_request(struct vhost_dev *dev)
+/*
+ * The use of this function is for requests that only need to be
+ * applied once. Typically such request occurs at the beginning
+ * of operation, and before setting up queues. It should not be
+ * used for request that performs operation until all queues are
+ * set, which would need to check dev->vq_index_end instead.
+ */
+static bool vhost_vdpa_first_dev(struct vhost_dev *dev)
 {
     struct vhost_vdpa *v = dev->opaque;
 
-    return v->index != 0;
+    return v->index == 0;
 }
 
 static int vhost_vdpa_get_dev_features(struct vhost_dev *dev,
@@ -451,7 +458,7 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void *opaque, Error **errp)
 
     vhost_vdpa_get_iova_range(v);
 
-    if (vhost_vdpa_one_time_request(dev)) {
+    if (!vhost_vdpa_first_dev(dev)) {
         return 0;
     }
 
@@ -594,7 +601,7 @@ static int vhost_vdpa_memslots_limit(struct vhost_dev *dev)
 static int vhost_vdpa_set_mem_table(struct vhost_dev *dev,
                                     struct vhost_memory *mem)
 {
-    if (vhost_vdpa_one_time_request(dev)) {
+    if (!vhost_vdpa_first_dev(dev)) {
         return 0;
     }
 
@@ -623,7 +630,7 @@ static int vhost_vdpa_set_features(struct vhost_dev *dev,
     struct vhost_vdpa *v = dev->opaque;
     int ret;
 
-    if (vhost_vdpa_one_time_request(dev)) {
+    if (!vhost_vdpa_first_dev(dev)) {
         return 0;
     }
 
@@ -665,7 +672,7 @@ static int vhost_vdpa_set_backend_cap(struct vhost_dev *dev)
 
     features &= f;
 
-    if (!vhost_vdpa_one_time_request(dev)) {
+    if (vhost_vdpa_first_dev(dev)) {
         r = vhost_vdpa_call(dev, VHOST_SET_BACKEND_FEATURES, &features);
         if (r) {
             return -EFAULT;
@@ -1118,7 +1125,7 @@ static int vhost_vdpa_set_log_base(struct vhost_dev *dev, uint64_t base,
                                      struct vhost_log *log)
 {
     struct vhost_vdpa *v = dev->opaque;
-    if (v->shadow_vqs_enabled || vhost_vdpa_one_time_request(dev)) {
+    if (v->shadow_vqs_enabled || !vhost_vdpa_first_dev(dev)) {
         return 0;
     }
 
@@ -1240,7 +1247,7 @@ static int vhost_vdpa_get_features(struct vhost_dev *dev,
 
 static int vhost_vdpa_set_owner(struct vhost_dev *dev)
 {
-    if (vhost_vdpa_one_time_request(dev)) {
+    if (!vhost_vdpa_first_dev(dev)) {
         return 0;
     }
 
-- 
2.31.1