From 25abc060d282132ea5c945392f900dca0a7e9bbb Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@redhat.com>
Date: Tue, 4 Aug 2020 19:20:40 +0300
Subject: [PATCH] vhost-vdpa: support IOTLB batching hints
This patches extend the vhost IOTLB API to accept batch updating hints
form userspace. When userspace wants update the device IOTLB in a
batch, it may do:
1) Write vhost_iotlb_msg with VHOST_IOTLB_BATCH_BEGIN flag
2) Perform a batch of IOTLB updating via VHOST_IOTLB_UPDATE/INVALIDATE
3) Write vhost_iotlb_msg with VHOST_IOTLB_BATCH_END flag
Vhost-vdpa may decide to batch the IOMMU/IOTLB updating in step 3 when
vDPA device support set_map() ops. This is useful for the vDPA device
that want to know all the mappings to tweak their own DMA translation
logic.
For vDPA device that doesn't require set_map(), no behavior changes.
This capability is advertised via VHOST_BACKEND_F_IOTLB_BATCH capability.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20200804162048.22587-5-eli@mellanox.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/vhost/vdpa.c | 36 ++++++++++++++++++++++++--------
include/uapi/linux/vhost.h | 2 ++
include/uapi/linux/vhost_types.h | 11 ++++++++++
3 files changed, 40 insertions(+), 9 deletions(-)
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 61c17d34cb392..e80db051845db 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -27,7 +27,9 @@
#include "vhost.h"
enum {
- VHOST_VDPA_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
+ VHOST_VDPA_BACKEND_FEATURES =
+ (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2) |
+ (1ULL << VHOST_BACKEND_F_IOTLB_BATCH),
};
/* Currently, only network backend w/o multiqueue is supported. */
@@ -48,6 +50,7 @@ struct vhost_vdpa {
int virtio_id;
int minor;
struct eventfd_ctx *config_ctx;
+ int in_batch;
};
static DEFINE_IDA(vhost_vdpa_ida);
@@ -124,6 +127,7 @@ static void vhost_vdpa_reset(struct vhost_vdpa *v)
struct vdpa_device *vdpa = v->vdpa;
vdpa_reset(vdpa);
+ v->in_batch = 0;
}
static long vhost_vdpa_get_device_id(struct vhost_vdpa *v, u8 __user *argp)
@@ -546,13 +550,15 @@ static int vhost_vdpa_map(struct vhost_vdpa *v,
if (r)
return r;
- if (ops->dma_map)
+ if (ops->dma_map) {
r = ops->dma_map(vdpa, iova, size, pa, perm);
- else if (ops->set_map)
- r = ops->set_map(vdpa, dev->iotlb);
- else
+ } else if (ops->set_map) {
+ if (!v->in_batch)
+ r = ops->set_map(vdpa, dev->iotlb);
+ } else {
r = iommu_map(v->domain, iova, pa, size,
perm_to_iommu_flags(perm));
+ }
return r;
}
@@ -565,12 +571,14 @@ static void vhost_vdpa_unmap(struct vhost_vdpa *v, u64 iova, u64 size)
vhost_vdpa_iotlb_unmap(v, iova, iova + size - 1);
- if (ops->dma_map)
+ if (ops->dma_map) {
ops->dma_unmap(vdpa, iova, size);
- else if (ops->set_map)
- ops->set_map(vdpa, dev->iotlb);
- else
+ } else if (ops->set_map) {
+ if (!v->in_batch)
+ ops->set_map(vdpa, dev->iotlb);
+ } else {
iommu_unmap(v->domain, iova, size);
+ }
}
static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
@@ -663,6 +671,8 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
struct vhost_iotlb_msg *msg)
{
struct vhost_vdpa *v = container_of(dev, struct vhost_vdpa, vdev);
+ struct vdpa_device *vdpa = v->vdpa;
+ const struct vdpa_config_ops *ops = vdpa->config;
int r = 0;
r = vhost_dev_check_owner(dev);
@@ -676,6 +686,14 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
case VHOST_IOTLB_INVALIDATE:
vhost_vdpa_unmap(v, msg->iova, msg->size);
break;
+ case VHOST_IOTLB_BATCH_BEGIN:
+ v->in_batch = true;
+ break;
+ case VHOST_IOTLB_BATCH_END:
+ if (v->in_batch && ops->set_map)
+ ops->set_map(vdpa, dev->iotlb);
+ v->in_batch = false;
+ break;
default:
r = -EINVAL;
break;
diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index 0c2349612e776..75232185324ab 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -91,6 +91,8 @@
/* Use message type V2 */
#define VHOST_BACKEND_F_IOTLB_MSG_V2 0x1
+/* IOTLB can accept batching hints */
+#define VHOST_BACKEND_F_IOTLB_BATCH 0x2
#define VHOST_SET_BACKEND_FEATURES _IOW(VHOST_VIRTIO, 0x25, __u64)
#define VHOST_GET_BACKEND_FEATURES _IOR(VHOST_VIRTIO, 0x26, __u64)
diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
index 669457ce5c484..9a269a88a6ffd 100644
--- a/include/uapi/linux/vhost_types.h
+++ b/include/uapi/linux/vhost_types.h
@@ -60,6 +60,17 @@ struct vhost_iotlb_msg {
#define VHOST_IOTLB_UPDATE 2
#define VHOST_IOTLB_INVALIDATE 3
#define VHOST_IOTLB_ACCESS_FAIL 4
+/*
+ * VHOST_IOTLB_BATCH_BEGIN and VHOST_IOTLB_BATCH_END allow modifying
+ * multiple mappings in one go: beginning with
+ * VHOST_IOTLB_BATCH_BEGIN, followed by any number of
+ * VHOST_IOTLB_UPDATE messages, and ending with VHOST_IOTLB_BATCH_END.
+ * When one of these two values is used as the message type, the rest
+ * of the fields in the message are ignored. There's no guarantee that
+ * these changes take place automatically in the device.
+ */
+#define VHOST_IOTLB_BATCH_BEGIN 5
+#define VHOST_IOTLB_BATCH_END 6
__u8 type;
};
--
2.30.2