summaryrefslogtreecommitdiff
path: root/arch/um/drivers
diff options
context:
space:
mode:
authorBenjamin Beichler <benjamin.beichler@uni-rostock.de>2022-06-07 11:27:14 +0000
committerRichard Weinberger <richard@nod.at>2022-09-19 22:28:25 +0200
commit714e76347a4e0bbd39730ddbb2c7e56971ba7caa (patch)
treee1075a36fcf3b9abd0d9a1ca1108ef357a48b1ee /arch/um/drivers
parent521a547ced6477c54b4b0cc206000406c221b4d6 (diff)
um: read multiple msg from virtio slave request fd
If VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS is activated, the user mode linux virtio irq handler only read one msg from the corresponding socket. This creates issues, when the device emulation creates multiple call requests (e.g. for multiple virtqueues), as the socket buffer tend to fill up and the call requests are delayed. This creates a deadlock situation, when the device simulation blocks, because of sending a msg and the kernel side blocks because of synchronously waiting for an acknowledge of kick request. Actually inband notifications are meant to be used in combination with the time travel protocol, but it is not required, therefore this corner case needs to be handled. Anyways, in general it seems to be more natural to consume always all messages from a socket, instead of only a single one. Fixes: 2cd097ba8c05 ("um: virtio: Implement VHOST_USER_PROTOCOL_F_SLAVE_REQ") Signed-off-by: Benjamin Beichler <benjamin.beichler@uni-rostock.de> Reviewed-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/drivers')
-rw-r--r--arch/um/drivers/virtio_uml.c71
1 files changed, 37 insertions, 34 deletions
diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index e719af8bdf56..588930a0ced1 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -374,45 +374,48 @@ static irqreturn_t vu_req_read_message(struct virtio_uml_device *vu_dev,
u8 extra_payload[512];
} msg;
int rc;
+ irqreturn_t irq_rc = IRQ_NONE;
- rc = vhost_user_recv_req(vu_dev, &msg.msg,
- sizeof(msg.msg.payload) +
- sizeof(msg.extra_payload));
-
- vu_dev->recv_rc = rc;
- if (rc)
- return IRQ_NONE;
-
- switch (msg.msg.header.request) {
- case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG:
- vu_dev->config_changed_irq = true;
- response = 0;
- break;
- case VHOST_USER_SLAVE_VRING_CALL:
- virtio_device_for_each_vq((&vu_dev->vdev), vq) {
- if (vq->index == msg.msg.payload.vring_state.index) {
- response = 0;
- vu_dev->vq_irq_vq_map |= BIT_ULL(vq->index);
- break;
+ while (1) {
+ rc = vhost_user_recv_req(vu_dev, &msg.msg,
+ sizeof(msg.msg.payload) +
+ sizeof(msg.extra_payload));
+ if (rc)
+ break;
+
+ switch (msg.msg.header.request) {
+ case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG:
+ vu_dev->config_changed_irq = true;
+ response = 0;
+ break;
+ case VHOST_USER_SLAVE_VRING_CALL:
+ virtio_device_for_each_vq((&vu_dev->vdev), vq) {
+ if (vq->index == msg.msg.payload.vring_state.index) {
+ response = 0;
+ vu_dev->vq_irq_vq_map |= BIT_ULL(vq->index);
+ break;
+ }
}
+ break;
+ case VHOST_USER_SLAVE_IOTLB_MSG:
+ /* not supported - VIRTIO_F_ACCESS_PLATFORM */
+ case VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG:
+ /* not supported - VHOST_USER_PROTOCOL_F_HOST_NOTIFIER */
+ default:
+ vu_err(vu_dev, "unexpected slave request %d\n",
+ msg.msg.header.request);
}
- break;
- case VHOST_USER_SLAVE_IOTLB_MSG:
- /* not supported - VIRTIO_F_ACCESS_PLATFORM */
- case VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG:
- /* not supported - VHOST_USER_PROTOCOL_F_HOST_NOTIFIER */
- default:
- vu_err(vu_dev, "unexpected slave request %d\n",
- msg.msg.header.request);
- }
-
- if (ev && !vu_dev->suspended)
- time_travel_add_irq_event(ev);
- if (msg.msg.header.flags & VHOST_USER_FLAG_NEED_REPLY)
- vhost_user_reply(vu_dev, &msg.msg, response);
+ if (ev && !vu_dev->suspended)
+ time_travel_add_irq_event(ev);
- return IRQ_HANDLED;
+ if (msg.msg.header.flags & VHOST_USER_FLAG_NEED_REPLY)
+ vhost_user_reply(vu_dev, &msg.msg, response);
+ irq_rc = IRQ_HANDLED;
+ };
+ /* mask EAGAIN as we try non-blocking read until socket is empty */
+ vu_dev->recv_rc = (rc == -EAGAIN) ? 0 : rc;
+ return irq_rc;
}
static irqreturn_t vu_req_interrupt(int irq, void *data)