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qemu/hw/virtio/vhost-backend.c
Kevin Wolf 28770ff935 vhost: Distinguish errors in vhost_backend_init() 
Instead of just returning 0/-1 and letting the caller make up a
meaningless error message, add an Error parameter to allow reporting the
real error and switch to 0/-errno so that different kind of errors can
be distinguished in the caller.

Specifically, in vhost-user, EPROTO is used for all errors that relate
to the connection itself, whereas other error codes are used for errors
relating to the content of the connection. This will allow us later to
automatically reconnect when the connection goes away, without ending up
in an endless loop if it's a permanent error in the configuration.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210609154658.350308-3-kwolf@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2021-06-30 13:16:03 +02:00

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/*
* vhost-backend
*
* Copyright (c) 2013 Virtual Open Systems Sarl.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "hw/virtio/vhost.h"
#include "hw/virtio/vhost-backend.h"
#include "qemu/error-report.h"
#include "qemu/main-loop.h"
#include "standard-headers/linux/vhost_types.h"
#include "hw/virtio/vhost-vdpa.h"
#ifdef CONFIG_VHOST_KERNEL
#include <linux/vhost.h>
#include <sys/ioctl.h>
static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int request,
void *arg)
{
int fd = (uintptr_t) dev->opaque;
assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_KERNEL);
return ioctl(fd, request, arg);
}
static int vhost_kernel_init(struct vhost_dev *dev, void *opaque, Error **errp)
{
assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_KERNEL);
dev->opaque = opaque;
return 0;
}
static int vhost_kernel_cleanup(struct vhost_dev *dev)
{
int fd = (uintptr_t) dev->opaque;
assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_KERNEL);
return close(fd);
}
static int vhost_kernel_memslots_limit(struct vhost_dev *dev)
{
int limit = 64;
char *s;
if (g_file_get_contents("/sys/module/vhost/parameters/max_mem_regions",
&s, NULL, NULL)) {
uint64_t val = g_ascii_strtoull(s, NULL, 10);
if (!((val == G_MAXUINT64 || !val) && errno)) {
g_free(s);
return val;
}
error_report("ignoring invalid max_mem_regions value in vhost module:"
" %s", s);
}
g_free(s);
return limit;
}
static int vhost_kernel_net_set_backend(struct vhost_dev *dev,
struct vhost_vring_file *file)
{
return vhost_kernel_call(dev, VHOST_NET_SET_BACKEND, file);
}
static int vhost_kernel_scsi_set_endpoint(struct vhost_dev *dev,
struct vhost_scsi_target *target)
{
return vhost_kernel_call(dev, VHOST_SCSI_SET_ENDPOINT, target);
}
static int vhost_kernel_scsi_clear_endpoint(struct vhost_dev *dev,
struct vhost_scsi_target *target)
{
return vhost_kernel_call(dev, VHOST_SCSI_CLEAR_ENDPOINT, target);
}
static int vhost_kernel_scsi_get_abi_version(struct vhost_dev *dev, int *version)
{
return vhost_kernel_call(dev, VHOST_SCSI_GET_ABI_VERSION, version);
}
static int vhost_kernel_set_log_base(struct vhost_dev *dev, uint64_t base,
struct vhost_log *log)
{
return vhost_kernel_call(dev, VHOST_SET_LOG_BASE, &base);
}
static int vhost_kernel_set_mem_table(struct vhost_dev *dev,
struct vhost_memory *mem)
{
return vhost_kernel_call(dev, VHOST_SET_MEM_TABLE, mem);
}
static int vhost_kernel_set_vring_addr(struct vhost_dev *dev,
struct vhost_vring_addr *addr)
{
return vhost_kernel_call(dev, VHOST_SET_VRING_ADDR, addr);
}
static int vhost_kernel_set_vring_endian(struct vhost_dev *dev,
struct vhost_vring_state *ring)
{
return vhost_kernel_call(dev, VHOST_SET_VRING_ENDIAN, ring);
}
static int vhost_kernel_set_vring_num(struct vhost_dev *dev,
struct vhost_vring_state *ring)
{
return vhost_kernel_call(dev, VHOST_SET_VRING_NUM, ring);
}
static int vhost_kernel_set_vring_base(struct vhost_dev *dev,
struct vhost_vring_state *ring)
{
return vhost_kernel_call(dev, VHOST_SET_VRING_BASE, ring);
}
static int vhost_kernel_get_vring_base(struct vhost_dev *dev,
struct vhost_vring_state *ring)
{
return vhost_kernel_call(dev, VHOST_GET_VRING_BASE, ring);
}
static int vhost_kernel_set_vring_kick(struct vhost_dev *dev,
struct vhost_vring_file *file)
{
return vhost_kernel_call(dev, VHOST_SET_VRING_KICK, file);
}
static int vhost_kernel_set_vring_call(struct vhost_dev *dev,
struct vhost_vring_file *file)
{
return vhost_kernel_call(dev, VHOST_SET_VRING_CALL, file);
}
static int vhost_kernel_set_vring_busyloop_timeout(struct vhost_dev *dev,
struct vhost_vring_state *s)
{
return vhost_kernel_call(dev, VHOST_SET_VRING_BUSYLOOP_TIMEOUT, s);
}
static int vhost_kernel_set_features(struct vhost_dev *dev,
uint64_t features)
{
return vhost_kernel_call(dev, VHOST_SET_FEATURES, &features);
}
static int vhost_kernel_set_backend_cap(struct vhost_dev *dev)
{
uint64_t features;
uint64_t f = 0x1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2;
int r;
if (vhost_kernel_call(dev, VHOST_GET_BACKEND_FEATURES, &features)) {
return 0;
}
features &= f;
r = vhost_kernel_call(dev, VHOST_SET_BACKEND_FEATURES,
&features);
if (r) {
return 0;
}
dev->backend_cap = features;
return 0;
}
static int vhost_kernel_get_features(struct vhost_dev *dev,
uint64_t *features)
{
return vhost_kernel_call(dev, VHOST_GET_FEATURES, features);
}
static int vhost_kernel_set_owner(struct vhost_dev *dev)
{
return vhost_kernel_call(dev, VHOST_SET_OWNER, NULL);
}
static int vhost_kernel_reset_device(struct vhost_dev *dev)
{
return vhost_kernel_call(dev, VHOST_RESET_OWNER, NULL);
}
static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
{
assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
return idx - dev->vq_index;
}
#ifdef CONFIG_VHOST_VSOCK
static int vhost_kernel_vsock_set_guest_cid(struct vhost_dev *dev,
uint64_t guest_cid)
{
return vhost_kernel_call(dev, VHOST_VSOCK_SET_GUEST_CID, &guest_cid);
}
static int vhost_kernel_vsock_set_running(struct vhost_dev *dev, int start)
{
return vhost_kernel_call(dev, VHOST_VSOCK_SET_RUNNING, &start);
}
#endif /* CONFIG_VHOST_VSOCK */
static void vhost_kernel_iotlb_read(void *opaque)
{
struct vhost_dev *dev = opaque;
ssize_t len;
if (dev->backend_cap &
(0x1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)) {
struct vhost_msg_v2 msg;
while ((len = read((uintptr_t)dev->opaque, &msg, sizeof msg)) > 0) {
if (len < sizeof msg) {
error_report("Wrong vhost message len: %d", (int)len);
break;
}
if (msg.type != VHOST_IOTLB_MSG_V2) {
error_report("Unknown vhost iotlb message type");
break;
}
vhost_backend_handle_iotlb_msg(dev, &msg.iotlb);
}
} else {
struct vhost_msg msg;
while ((len = read((uintptr_t)dev->opaque, &msg, sizeof msg)) > 0) {
if (len < sizeof msg) {
error_report("Wrong vhost message len: %d", (int)len);
break;
}
if (msg.type != VHOST_IOTLB_MSG) {
error_report("Unknown vhost iotlb message type");
break;
}
vhost_backend_handle_iotlb_msg(dev, &msg.iotlb);
}
}
}
static int vhost_kernel_send_device_iotlb_msg(struct vhost_dev *dev,
struct vhost_iotlb_msg *imsg)
{
if (dev->backend_cap & (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)) {
struct vhost_msg_v2 msg = {};
msg.type = VHOST_IOTLB_MSG_V2;
msg.iotlb = *imsg;
if (write((uintptr_t)dev->opaque, &msg, sizeof msg) != sizeof msg) {
error_report("Fail to update device iotlb");
return -EFAULT;
}
} else {
struct vhost_msg msg = {};
msg.type = VHOST_IOTLB_MSG;
msg.iotlb = *imsg;
if (write((uintptr_t)dev->opaque, &msg, sizeof msg) != sizeof msg) {
error_report("Fail to update device iotlb");
return -EFAULT;
}
}
return 0;
}
static void vhost_kernel_set_iotlb_callback(struct vhost_dev *dev,
int enabled)
{
if (enabled)
qemu_set_fd_handler((uintptr_t)dev->opaque,
vhost_kernel_iotlb_read, NULL, dev);
else
qemu_set_fd_handler((uintptr_t)dev->opaque, NULL, NULL, NULL);
}
static const VhostOps kernel_ops = {
.backend_type = VHOST_BACKEND_TYPE_KERNEL,
.vhost_backend_init = vhost_kernel_init,
.vhost_backend_cleanup = vhost_kernel_cleanup,
.vhost_backend_memslots_limit = vhost_kernel_memslots_limit,
.vhost_net_set_backend = vhost_kernel_net_set_backend,
.vhost_scsi_set_endpoint = vhost_kernel_scsi_set_endpoint,
.vhost_scsi_clear_endpoint = vhost_kernel_scsi_clear_endpoint,
.vhost_scsi_get_abi_version = vhost_kernel_scsi_get_abi_version,
.vhost_set_log_base = vhost_kernel_set_log_base,
.vhost_set_mem_table = vhost_kernel_set_mem_table,
.vhost_set_vring_addr = vhost_kernel_set_vring_addr,
.vhost_set_vring_endian = vhost_kernel_set_vring_endian,
.vhost_set_vring_num = vhost_kernel_set_vring_num,
.vhost_set_vring_base = vhost_kernel_set_vring_base,
.vhost_get_vring_base = vhost_kernel_get_vring_base,
.vhost_set_vring_kick = vhost_kernel_set_vring_kick,
.vhost_set_vring_call = vhost_kernel_set_vring_call,
.vhost_set_vring_busyloop_timeout =
vhost_kernel_set_vring_busyloop_timeout,
.vhost_set_features = vhost_kernel_set_features,
.vhost_get_features = vhost_kernel_get_features,
.vhost_set_backend_cap = vhost_kernel_set_backend_cap,
.vhost_set_owner = vhost_kernel_set_owner,
.vhost_reset_device = vhost_kernel_reset_device,
.vhost_get_vq_index = vhost_kernel_get_vq_index,
#ifdef CONFIG_VHOST_VSOCK
.vhost_vsock_set_guest_cid = vhost_kernel_vsock_set_guest_cid,
.vhost_vsock_set_running = vhost_kernel_vsock_set_running,
#endif /* CONFIG_VHOST_VSOCK */
.vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
.vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
};
#endif
int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)
{
int r = 0;
switch (backend_type) {
#ifdef CONFIG_VHOST_KERNEL
case VHOST_BACKEND_TYPE_KERNEL:
dev->vhost_ops = &kernel_ops;
break;
#endif
#ifdef CONFIG_VHOST_USER
case VHOST_BACKEND_TYPE_USER:
dev->vhost_ops = &user_ops;
break;
#endif
#ifdef CONFIG_VHOST_VDPA
case VHOST_BACKEND_TYPE_VDPA:
dev->vhost_ops = &vdpa_ops;
break;
#endif
default:
error_report("Unknown vhost backend type");
r = -1;
}
return r;
}
int vhost_backend_update_device_iotlb(struct vhost_dev *dev,
uint64_t iova, uint64_t uaddr,
uint64_t len,
IOMMUAccessFlags perm)
{
struct vhost_iotlb_msg imsg;
imsg.iova = iova;
imsg.uaddr = uaddr;
imsg.size = len;
imsg.type = VHOST_IOTLB_UPDATE;
switch (perm) {
case IOMMU_RO:
imsg.perm = VHOST_ACCESS_RO;
break;
case IOMMU_WO:
imsg.perm = VHOST_ACCESS_WO;
break;
case IOMMU_RW:
imsg.perm = VHOST_ACCESS_RW;
break;
default:
return -EINVAL;
}
if (dev->vhost_ops && dev->vhost_ops->vhost_send_device_iotlb_msg)
return dev->vhost_ops->vhost_send_device_iotlb_msg(dev, &imsg);
return -ENODEV;
}
int vhost_backend_invalidate_device_iotlb(struct vhost_dev *dev,
uint64_t iova, uint64_t len)
{
struct vhost_iotlb_msg imsg;
imsg.iova = iova;
imsg.size = len;
imsg.type = VHOST_IOTLB_INVALIDATE;
if (dev->vhost_ops && dev->vhost_ops->vhost_send_device_iotlb_msg)
return dev->vhost_ops->vhost_send_device_iotlb_msg(dev, &imsg);
return -ENODEV;
}
int vhost_backend_handle_iotlb_msg(struct vhost_dev *dev,
struct vhost_iotlb_msg *imsg)
{
int ret = 0;
if (unlikely(!dev->vdev)) {
error_report("Unexpected IOTLB message when virtio device is stopped");
return -EINVAL;
}
switch (imsg->type) {
case VHOST_IOTLB_MISS:
ret = vhost_device_iotlb_miss(dev, imsg->iova,
imsg->perm != VHOST_ACCESS_RO);
break;
case VHOST_IOTLB_ACCESS_FAIL:
/* FIXME: report device iotlb error */
error_report("Access failure IOTLB message type not supported");
ret = -ENOTSUP;
break;
case VHOST_IOTLB_UPDATE:
case VHOST_IOTLB_INVALIDATE:
default:
error_report("Unexpected IOTLB message type");
ret = -EINVAL;
break;
}
return ret;
}
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