From 88ce642492339f49a0b391af40e5798c08948e49 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 13 Feb 2020 14:26:47 +0100 Subject: um: Implement time-travel=ext 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 Signed-off-by: Richard Weinberger --- arch/um/drivers/virtio_uml.c | 68 +++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 64 insertions(+), 4 deletions(-) (limited to 'arch/um/drivers') diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c index 9b4c5b7c0f0d..be54d368e73d 100644 --- a/arch/um/drivers/virtio_uml.c +++ b/arch/um/drivers/virtio_uml.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include #include @@ -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)) { -- cgit