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/*
* vhost shadow virtqueue
*
* SPDX-FileCopyrightText: Red Hat, Inc. 2021
* SPDX-FileContributor: Author: Eugenio Pérez <eperezma@redhat.com>
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "hw/virtio/vhost-shadow-virtqueue.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "qemu/main-loop.h"
#include "linux-headers/linux/vhost.h"
/**
* Validate the transport device features that both guests can use with the SVQ
* and SVQs can use with the device.
*
* @dev_features: The features
* @errp: Error pointer
*/
bool vhost_svq_valid_features(uint64_t features, Error **errp)
{
bool ok = true;
uint64_t svq_features = features;
for (uint64_t b = VIRTIO_TRANSPORT_F_START; b <= VIRTIO_TRANSPORT_F_END;
++b) {
switch (b) {
case VIRTIO_F_ANY_LAYOUT:
continue;
case VIRTIO_F_ACCESS_PLATFORM:
/* SVQ trust in the host's IOMMU to translate addresses */
case VIRTIO_F_VERSION_1:
/* SVQ trust that the guest vring is little endian */
if (!(svq_features & BIT_ULL(b))) {
svq_features |= BIT_ULL(b);
ok = false;
}
continue;
default:
if (svq_features & BIT_ULL(b)) {
svq_features &= ~BIT_ULL(b);
ok = false;
}
}
}
if (!ok) {
error_setg(errp, "SVQ Invalid device feature flags, offer: 0x%"PRIx64
", ok: 0x%"PRIx64, features, svq_features);
}
return ok;
}
/**
* Forward guest notifications.
*
* @n: guest kick event notifier, the one that guest set to notify svq.
*/
static void vhost_handle_guest_kick(EventNotifier *n)
{
VhostShadowVirtqueue *svq = container_of(n, VhostShadowVirtqueue, svq_kick);
event_notifier_test_and_clear(n);
event_notifier_set(&svq->hdev_kick);
}
/**
* Forward vhost notifications
*
* @n: hdev call event notifier, the one that device set to notify svq.
*/
static void vhost_svq_handle_call(EventNotifier *n)
{
VhostShadowVirtqueue *svq = container_of(n, VhostShadowVirtqueue,
hdev_call);
event_notifier_test_and_clear(n);
event_notifier_set(&svq->svq_call);
}
/**
* Set the call notifier for the SVQ to call the guest
*
* @svq: Shadow virtqueue
* @call_fd: call notifier
*
* Called on BQL context.
*/
void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue *svq, int call_fd)
{
if (call_fd == VHOST_FILE_UNBIND) {
/*
* Fail event_notifier_set if called handling device call.
*
* SVQ still needs device notifications, since it needs to keep
* forwarding used buffers even with the unbind.
*/
memset(&svq->svq_call, 0, sizeof(svq->svq_call));
} else {
event_notifier_init_fd(&svq->svq_call, call_fd);
}
}
/**
* Get the shadow vq vring address.
* @svq: Shadow virtqueue
* @addr: Destination to store address
*/
void vhost_svq_get_vring_addr(const VhostShadowVirtqueue *svq,
struct vhost_vring_addr *addr)
{
addr->desc_user_addr = (uint64_t)(intptr_t)svq->vring.desc;
addr->avail_user_addr = (uint64_t)(intptr_t)svq->vring.avail;
addr->used_user_addr = (uint64_t)(intptr_t)svq->vring.used;
}
size_t vhost_svq_driver_area_size(const VhostShadowVirtqueue *svq)
{
size_t desc_size = sizeof(vring_desc_t) * svq->vring.num;
size_t avail_size = offsetof(vring_avail_t, ring) +
sizeof(uint16_t) * svq->vring.num;
return ROUND_UP(desc_size + avail_size, qemu_real_host_page_size);
}
size_t vhost_svq_device_area_size(const VhostShadowVirtqueue *svq)
{
size_t used_size = offsetof(vring_used_t, ring) +
sizeof(vring_used_elem_t) * svq->vring.num;
return ROUND_UP(used_size, qemu_real_host_page_size);
}
/**
* Set a new file descriptor for the guest to kick the SVQ and notify for avail
*
* @svq: The svq
* @svq_kick_fd: The svq kick fd
*
* Note that the SVQ will never close the old file descriptor.
*/
void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd)
{
EventNotifier *svq_kick = &svq->svq_kick;
bool poll_stop = VHOST_FILE_UNBIND != event_notifier_get_fd(svq_kick);
bool poll_start = svq_kick_fd != VHOST_FILE_UNBIND;
if (poll_stop) {
event_notifier_set_handler(svq_kick, NULL);
}
/*
* event_notifier_set_handler already checks for guest's notifications if
* they arrive at the new file descriptor in the switch, so there is no
* need to explicitly check for them.
*/
if (poll_start) {
event_notifier_init_fd(svq_kick, svq_kick_fd);
event_notifier_set(svq_kick);
event_notifier_set_handler(svq_kick, vhost_handle_guest_kick);
}
}
/**
* Stop the shadow virtqueue operation.
* @svq: Shadow Virtqueue
*/
void vhost_svq_stop(VhostShadowVirtqueue *svq)
{
event_notifier_set_handler(&svq->svq_kick, NULL);
}
/**
* Creates vhost shadow virtqueue, and instructs the vhost device to use the
* shadow methods and file descriptors.
*
* Returns the new virtqueue or NULL.
*
* In case of error, reason is reported through error_report.
*/
VhostShadowVirtqueue *vhost_svq_new(void)
{
g_autofree VhostShadowVirtqueue *svq = g_new0(VhostShadowVirtqueue, 1);
int r;
r = event_notifier_init(&svq->hdev_kick, 0);
if (r != 0) {
error_report("Couldn't create kick event notifier: %s (%d)",
g_strerror(errno), errno);
goto err_init_hdev_kick;
}
r = event_notifier_init(&svq->hdev_call, 0);
if (r != 0) {
error_report("Couldn't create call event notifier: %s (%d)",
g_strerror(errno), errno);
goto err_init_hdev_call;
}
event_notifier_init_fd(&svq->svq_kick, VHOST_FILE_UNBIND);
event_notifier_set_handler(&svq->hdev_call, vhost_svq_handle_call);
return g_steal_pointer(&svq);
err_init_hdev_call:
event_notifier_cleanup(&svq->hdev_kick);
err_init_hdev_kick:
return NULL;
}
/**
* Free the resources of the shadow virtqueue.
*
* @pvq: gpointer to SVQ so it can be used by autofree functions.
*/
void vhost_svq_free(gpointer pvq)
{
VhostShadowVirtqueue *vq = pvq;
vhost_svq_stop(vq);
event_notifier_cleanup(&vq->hdev_kick);
event_notifier_set_handler(&vq->hdev_call, NULL);
event_notifier_cleanup(&vq->hdev_call);
g_free(vq);
}
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