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um: Implement time-travel=ext

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This implements synchronized time-travel mode which - using a special
application on a unix socket - lets multiple machines take part in a
time-travelling simulation together.

The protocol for the unix domain socket is defined in the new file
include/uapi/linux/um_timetravel.h.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Johannes Berg
2020-02-13 14:26:47 +01:00
committed by Richard Weinberger
parent dd9ada5627
commit 88ce642492
7 changed files with 563 additions and 17 deletions
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68
arch/um/drivers/virtio_uml.c
View File

@@ -26,6 +26,7 @@
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/virtio_ring.h>
#include <linux/time-internal.h>
#include <shared/as-layout.h>
#include <irq_kern.h>
#include <init.h>
@@ -64,6 +65,11 @@ struct virtio_uml_device {
struct virtio_uml_vq_info {
int kick_fd, call_fd;
char name[32];
#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
struct virtqueue *vq;
vq_callback_t *callback;
struct time_travel_event defer;
#endif
};
extern unsigned long long physmem_size, highmem;
@@ -118,10 +124,27 @@ static int vhost_user_recv_header(int fd, struct vhost_user_msg *msg)
static int vhost_user_recv(struct virtio_uml_device *vu_dev,
int fd, struct vhost_user_msg *msg,
size_t max_payload_size)
size_t max_payload_size, bool wait)
{
size_t size;
int rc = vhost_user_recv_header(fd, msg);
int rc;
/*
* In virtio time-travel mode, we're handling all the vhost-user
* FDs by polling them whenever appropriate. However, we may get
* into a situation where we're sending out an interrupt message
* to a device (e.g. a net device) and need to handle a simulation
* time message while doing so, e.g. one that tells us to update
* our idea of how long we can run without scheduling.
*
* Thus, we need to not just read() from the given fd, but need
* to also handle messages for the simulation time - this function
* does that for us while waiting for the given fd to be readable.
*/
if (wait)
time_travel_wait_readable(fd);
rc = vhost_user_recv_header(fd, msg);
if (rc == -ECONNRESET && vu_dev->registered) {
struct virtio_uml_platform_data *pdata;
@@ -143,7 +166,8 @@ static int vhost_user_recv_resp(struct virtio_uml_device *vu_dev,
struct vhost_user_msg *msg,
size_t max_payload_size)
{
int rc = vhost_user_recv(vu_dev, vu_dev->sock, msg, max_payload_size);
int rc = vhost_user_recv(vu_dev, vu_dev->sock, msg,
max_payload_size, true);
if (rc)
return rc;
@@ -173,7 +197,8 @@ static int vhost_user_recv_req(struct virtio_uml_device *vu_dev,
struct vhost_user_msg *msg,
size_t max_payload_size)
{
int rc = vhost_user_recv(vu_dev, vu_dev->req_fd, msg, max_payload_size);
int rc = vhost_user_recv(vu_dev, vu_dev->req_fd, msg,
max_payload_size, false);
if (rc)
return rc;
@@ -700,6 +725,8 @@ static bool vu_notify(struct virtqueue *vq)
const uint64_t n = 1;
int rc;
time_travel_propagate_time();
if (info->kick_fd < 0) {
struct virtio_uml_device *vu_dev;
@@ -847,6 +874,23 @@ out:
return rc;
}
#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
static void vu_defer_irq_handle(struct time_travel_event *d)
{
struct virtio_uml_vq_info *info;
info = container_of(d, struct virtio_uml_vq_info, defer);
info->callback(info->vq);
}
static void vu_defer_irq_callback(struct virtqueue *vq)
{
struct virtio_uml_vq_info *info = vq->priv;
time_travel_add_irq_event(&info->defer);
}
#endif
static struct virtqueue *vu_setup_vq(struct virtio_device *vdev,
unsigned index, vq_callback_t *callback,
const char *name, bool ctx)
@@ -866,6 +910,19 @@ static struct virtqueue *vu_setup_vq(struct virtio_device *vdev,
snprintf(info->name, sizeof(info->name), "%s.%d-%s", pdev->name,
pdev->id, name);
#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
/*
* When we get an interrupt, we must bounce it through the simulation
* calendar (the simtime device), except for the simtime device itself
* since that's part of the simulation control.
*/
if (time_travel_mode == TT_MODE_EXTERNAL && callback) {
info->callback = callback;
callback = vu_defer_irq_callback;
time_travel_set_event_fn(&info->defer, vu_defer_irq_handle);
}
#endif
vq = vring_create_virtqueue(index, num, PAGE_SIZE, vdev, true, true,
ctx, vu_notify, callback, info->name);
if (!vq) {
@@ -874,6 +931,9 @@ static struct virtqueue *vu_setup_vq(struct virtio_device *vdev,
}
vq->priv = info;
num = virtqueue_get_vring_size(vq);
#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
info->vq = vq;
#endif
if (vu_dev->protocol_features &
BIT_ULL(VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS)) {