This patch introduces VHOST_USER_PROTOCOL_F_HOST_NOTIFIER.
With this feature negotiated, vhost-user backend can register
memory region based host notifiers. And it will allow the guest
driver in the VM to notify the hardware accelerator at the
vhost-user backend directly.
Signed-off-by: Tiwei Bie <address@hidden>
---
docs/interop/vhost-user.txt | 33 +++++++++
hw/virtio/vhost-user.c | 123 +++++++++++++++++++++++++++++++++
include/hw/virtio/vhost-user.h | 8 +++
3 files changed, 164 insertions(+)
diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
index 534caab18a..9e57b36b20 100644
--- a/docs/interop/vhost-user.txt
+++ b/docs/interop/vhost-user.txt
@@ -132,6 +132,16 @@ Depending on the request type, payload can be:
Payload: Size bytes array holding the contents of the virtio
device's configuration space
+ * Vring area description
+ -----------------------
+ | u64 | size | offset |
+ -----------------------
+
+ u64: a 64-bit integer contains vring index and flags
+ Size: a 64-bit size of this area
+ Offset: a 64-bit offset of this area from the start of the
+ supplied file descriptor
+
In QEMU the vhost-user message is implemented with the following struct:
typedef struct VhostUserMsg {
@@ -146,6 +156,7 @@ typedef struct VhostUserMsg {
VhostUserLog log;
struct vhost_iotlb_msg iotlb;
VhostUserConfig config;
+ VhostUserVringArea area;
};
} QEMU_PACKED VhostUserMsg;
@@ -380,6 +391,7 @@ Protocol features
#define VHOST_USER_PROTOCOL_F_CRYPTO_SESSION 7
#define VHOST_USER_PROTOCOL_F_PAGEFAULT 8
#define VHOST_USER_PROTOCOL_F_CONFIG 9
+#define VHOST_USER_PROTOCOL_F_HOST_NOTIFIER 10
Master message types
--------------------
@@ -777,6 +789,27 @@ Slave message types
the VHOST_USER_NEED_REPLY flag, master must respond with zero when
operation is successfully completed, or non-zero otherwise.
+ * VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG
+
+ Id: 3
+ Equivalent ioctl: N/A
+ Slave payload: vring area description
+ Master payload: N/A
+
+ Sets host notifier for a specified queue. The queue index is contained
+ in the u64 field of the vring area description. The host notifier is
+ described by the file descriptor (typically it's a VFIO device fd) which
+ is passed as ancillary data and the size (which is mmap size and should
+ be the same as host page size) and offset (which is mmap offset) carried
+ in the vring area description. QEMU can mmap the file descriptor based
+ on the size and offset to get a memory range. Registering a host notifier
+ means mapping this memory range to the VM as the specified queue's notify
+ MMIO region. Slave sends this request to tell QEMU to de-register the
+ existing notifier if any and register the new notifier if the request is
+ sent with a file descriptor.
+ This request should be sent only when VHOST_USER_PROTOCOL_F_HOST_NOTIFIER
+ protocol feature has been successfully negotiated.
+
VHOST_USER_PROTOCOL_F_REPLY_ACK:
-------------------------------
The original vhost-user specification only demands replies for certain
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 5f72ed68da..259a841af9 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -13,6 +13,7 @@
#include "hw/virtio/vhost.h"
#include "hw/virtio/vhost-user.h"
#include "hw/virtio/vhost-backend.h"
+#include "hw/virtio/virtio.h"
#include "hw/virtio/virtio-net.h"
#include "chardev/char-fe.h"
#include "sysemu/kvm.h"
@@ -48,6 +49,7 @@ enum VhostUserProtocolFeature {
VHOST_USER_PROTOCOL_F_CRYPTO_SESSION = 7,
VHOST_USER_PROTOCOL_F_PAGEFAULT = 8,
VHOST_USER_PROTOCOL_F_CONFIG = 9,
+ VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 10,
VHOST_USER_PROTOCOL_F_MAX
};
@@ -92,6 +94,7 @@ typedef enum VhostUserSlaveRequest {
VHOST_USER_SLAVE_NONE = 0,
VHOST_USER_SLAVE_IOTLB_MSG = 1,
VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
+ VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
VHOST_USER_SLAVE_MAX
} VhostUserSlaveRequest;
@@ -136,6 +139,12 @@ static VhostUserConfig c __attribute__ ((unused));
+ sizeof(c.size) \
+ sizeof(c.flags))
+typedef struct VhostUserVringArea {
+ uint64_t u64;
+ uint64_t size;
+ uint64_t offset;
+} VhostUserVringArea;
+
typedef struct {
VhostUserRequest request;
@@ -157,6 +166,7 @@ typedef union {
struct vhost_iotlb_msg iotlb;
VhostUserConfig config;
VhostUserCryptoSession session;
+ VhostUserVringArea area;
} VhostUserPayload;
typedef struct VhostUserMsg {
@@ -638,9 +648,37 @@ static int vhost_user_set_vring_num(struct vhost_dev *dev,
return vhost_set_vring(dev, VHOST_USER_SET_VRING_NUM, ring);
}
+static void vhost_user_host_notifier_restore(struct vhost_dev *dev,
+ int queue_idx)
+{
+ struct vhost_user *u = dev->opaque;
+ VhostUserHostNotifier *n = &u->user->notifier[queue_idx];
+ VirtIODevice *vdev = dev->vdev;
+
+ if (n->addr && !n->set) {
+ virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, true);
+ n->set = true;
+ }
+}
+
+static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
+ int queue_idx)
+{
+ struct vhost_user *u = dev->opaque;
+ VhostUserHostNotifier *n = &u->user->notifier[queue_idx];
+ VirtIODevice *vdev = dev->vdev;
+
+ if (n->addr && n->set) {
+ virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
+ n->set = false;
+ }
+}
+
static int vhost_user_set_vring_base(struct vhost_dev *dev,
struct vhost_vring_state *ring)
{
+ vhost_user_host_notifier_restore(dev, ring->index);
+
return vhost_set_vring(dev, VHOST_USER_SET_VRING_BASE, ring);
}
@@ -674,6 +712,8 @@ static int vhost_user_get_vring_base(struct vhost_dev *dev,
.hdr.size = sizeof(msg.payload.state),
};
+ vhost_user_host_notifier_remove(dev, ring->index);
+
if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
return -1;
}
@@ -847,6 +887,76 @@ static int vhost_user_slave_handle_config_change(struct
vhost_dev *dev)
return ret;
}
+static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
+ VhostUserVringArea
*area,
+ int fd)
+{
+ int queue_idx = area->u64 & VHOST_USER_VRING_IDX_MASK;
+ size_t page_size = qemu_real_host_page_size;
+ struct vhost_user *u = dev->opaque;
+ VhostUserState *user = u->user;
+ VirtIODevice *vdev = dev->vdev;
+ VhostUserHostNotifier *n;
+ int ret = 0;
+ void *addr;
+ char *name;
+
+ if (!virtio_has_feature(dev->protocol_features,
+ VHOST_USER_PROTOCOL_F_HOST_NOTIFIER) ||
+ vdev == NULL || queue_idx >= virtio_get_num_queues(vdev)) {
+ ret = -1;
+ goto out;
+ }
+
+ n = &user->notifier[queue_idx];
+
+ if (n->addr) {
+ virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
+ object_unparent(OBJECT(&n->mr));
+ munmap(n->addr, page_size);
+ n->addr = NULL;
+ }
+
+ if (area->u64 & VHOST_USER_VRING_NOFD_MASK) {
+ goto out;
+ }
+
+ /* Sanity check. */
+ if (area->size != page_size) {
+ ret = -1;
+ goto out;
+ }
+
+ addr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED,
+ fd, area->offset);
+ if (addr == MAP_FAILED) {
+ ret = -1;
+ goto out;
+ }
+
+ name = g_strdup_printf("vhost-user/address@hidden mmaps[%d]",
+ user, queue_idx);
+ memory_region_init_ram_device_ptr(&n->mr, OBJECT(vdev), name,
+ page_size, addr);
+ g_free(name);
+
+ if (virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, true)) {
+ munmap(addr, page_size);
+ ret = -1;
+ goto out;
+ }
+
+ n->addr = addr;
+ n->set = true;
+
+out:
+ /* Always close the fd. */
+ if (fd != -1) {
+ close(fd);
+ }
+ return ret;
+}
+
static void slave_read(void *opaque)
{
struct vhost_dev *dev = opaque;
@@ -913,6 +1023,10 @@ static void slave_read(void *opaque)
case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG :
ret = vhost_user_slave_handle_config_change(dev);
break;
+ case VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG:
+ ret = vhost_user_slave_handle_vring_host_notifier(dev, &payload.area,
+ fd);
+ break;
default:
error_report("Received unexpected msg type.");
if (fd != -1) {
@@ -1641,6 +1755,15 @@ VhostUserState *vhost_user_init(void)
void vhost_user_cleanup(VhostUserState *user)
{
+ int i;
+
+ for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
+ if (user->notifier[i].addr) {
+ object_unparent(OBJECT(&user->notifier[i].mr));
+ munmap(user->notifier[i].addr, qemu_real_host_page_size);
+ user->notifier[i].addr = NULL;
+ }
+ }
}
const VhostOps user_ops = {
diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
index eb8bc0d90d..fd660393a0 100644
--- a/include/hw/virtio/vhost-user.h
+++ b/include/hw/virtio/vhost-user.h
@@ -9,9 +9,17 @@
#define HW_VIRTIO_VHOST_USER_H
#include "chardev/char-fe.h"
+#include "hw/virtio/virtio.h"
+
+typedef struct VhostUserHostNotifier {
+ MemoryRegion mr;
+ void *addr;
+ bool set;
+} VhostUserHostNotifier;
typedef struct VhostUserState {
CharBackend *chr;
+ VhostUserHostNotifier notifier[VIRTIO_QUEUE_MAX];
} VhostUserState;
VhostUserState *vhost_user_init(void);