| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/fs/9p/trans_xen |
| * |
| * Xen transport layer. |
| * |
| * Copyright (C) 2017 by Stefano Stabellini <stefano@aporeto.com> |
| */ |
| |
| #include <xen/events.h> |
| #include <xen/grant_table.h> |
| #include <xen/xen.h> |
| #include <xen/xenbus.h> |
| #include <xen/interface/io/9pfs.h> |
| |
| #include <linux/module.h> |
| #include <linux/spinlock.h> |
| #include <net/9p/9p.h> |
| #include <net/9p/client.h> |
| #include <net/9p/transport.h> |
| |
| #define XEN_9PFS_NUM_RINGS 2 |
| #define XEN_9PFS_RING_ORDER 9 |
| #define XEN_9PFS_RING_SIZE(ring) XEN_FLEX_RING_SIZE(ring->intf->ring_order) |
| |
| struct xen_9pfs_header { |
| uint32_t size; |
| uint8_t id; |
| uint16_t tag; |
| |
| /* uint8_t sdata[]; */ |
| } __attribute__((packed)); |
| |
| /* One per ring, more than one per 9pfs share */ |
| struct xen_9pfs_dataring { |
| struct xen_9pfs_front_priv *priv; |
| |
| struct xen_9pfs_data_intf *intf; |
| grant_ref_t ref; |
| int evtchn; |
| int irq; |
| /* protect a ring from concurrent accesses */ |
| spinlock_t lock; |
| |
| struct xen_9pfs_data data; |
| wait_queue_head_t wq; |
| struct work_struct work; |
| }; |
| |
| /* One per 9pfs share */ |
| struct xen_9pfs_front_priv { |
| struct list_head list; |
| struct xenbus_device *dev; |
| char *tag; |
| struct p9_client *client; |
| |
| int num_rings; |
| struct xen_9pfs_dataring *rings; |
| }; |
| |
| static LIST_HEAD(xen_9pfs_devs); |
| static DEFINE_RWLOCK(xen_9pfs_lock); |
| |
| /* We don't currently allow canceling of requests */ |
| static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req) |
| { |
| return 1; |
| } |
| |
| static int p9_xen_create(struct p9_client *client, const char *addr, char *args) |
| { |
| struct xen_9pfs_front_priv *priv; |
| |
| if (addr == NULL) |
| return -EINVAL; |
| |
| read_lock(&xen_9pfs_lock); |
| list_for_each_entry(priv, &xen_9pfs_devs, list) { |
| if (!strcmp(priv->tag, addr)) { |
| priv->client = client; |
| read_unlock(&xen_9pfs_lock); |
| return 0; |
| } |
| } |
| read_unlock(&xen_9pfs_lock); |
| return -EINVAL; |
| } |
| |
| static void p9_xen_close(struct p9_client *client) |
| { |
| struct xen_9pfs_front_priv *priv; |
| |
| read_lock(&xen_9pfs_lock); |
| list_for_each_entry(priv, &xen_9pfs_devs, list) { |
| if (priv->client == client) { |
| priv->client = NULL; |
| read_unlock(&xen_9pfs_lock); |
| return; |
| } |
| } |
| read_unlock(&xen_9pfs_lock); |
| } |
| |
| static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size) |
| { |
| RING_IDX cons, prod; |
| |
| cons = ring->intf->out_cons; |
| prod = ring->intf->out_prod; |
| virt_mb(); |
| |
| return XEN_9PFS_RING_SIZE(ring) - |
| xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) >= size; |
| } |
| |
| static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) |
| { |
| struct xen_9pfs_front_priv *priv; |
| RING_IDX cons, prod, masked_cons, masked_prod; |
| unsigned long flags; |
| u32 size = p9_req->tc.size; |
| struct xen_9pfs_dataring *ring; |
| int num; |
| |
| read_lock(&xen_9pfs_lock); |
| list_for_each_entry(priv, &xen_9pfs_devs, list) { |
| if (priv->client == client) |
| break; |
| } |
| read_unlock(&xen_9pfs_lock); |
| if (list_entry_is_head(priv, &xen_9pfs_devs, list)) |
| return -EINVAL; |
| |
| num = p9_req->tc.tag % priv->num_rings; |
| ring = &priv->rings[num]; |
| |
| again: |
| while (wait_event_killable(ring->wq, |
| p9_xen_write_todo(ring, size)) != 0) |
| ; |
| |
| spin_lock_irqsave(&ring->lock, flags); |
| cons = ring->intf->out_cons; |
| prod = ring->intf->out_prod; |
| virt_mb(); |
| |
| if (XEN_9PFS_RING_SIZE(ring) - |
| xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) < size) { |
| spin_unlock_irqrestore(&ring->lock, flags); |
| goto again; |
| } |
| |
| masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring)); |
| masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring)); |
| |
| xen_9pfs_write_packet(ring->data.out, p9_req->tc.sdata, size, |
| &masked_prod, masked_cons, |
| XEN_9PFS_RING_SIZE(ring)); |
| |
| p9_req->status = REQ_STATUS_SENT; |
| virt_wmb(); /* write ring before updating pointer */ |
| prod += size; |
| ring->intf->out_prod = prod; |
| spin_unlock_irqrestore(&ring->lock, flags); |
| notify_remote_via_irq(ring->irq); |
| p9_req_put(p9_req); |
| |
| return 0; |
| } |
| |
| static void p9_xen_response(struct work_struct *work) |
| { |
| struct xen_9pfs_front_priv *priv; |
| struct xen_9pfs_dataring *ring; |
| RING_IDX cons, prod, masked_cons, masked_prod; |
| struct xen_9pfs_header h; |
| struct p9_req_t *req; |
| int status; |
| |
| ring = container_of(work, struct xen_9pfs_dataring, work); |
| priv = ring->priv; |
| |
| while (1) { |
| cons = ring->intf->in_cons; |
| prod = ring->intf->in_prod; |
| virt_rmb(); |
| |
| if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) < |
| sizeof(h)) { |
| notify_remote_via_irq(ring->irq); |
| return; |
| } |
| |
| masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring)); |
| masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring)); |
| |
| /* First, read just the header */ |
| xen_9pfs_read_packet(&h, ring->data.in, sizeof(h), |
| masked_prod, &masked_cons, |
| XEN_9PFS_RING_SIZE(ring)); |
| |
| req = p9_tag_lookup(priv->client, h.tag); |
| if (!req || req->status != REQ_STATUS_SENT) { |
| dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag); |
| cons += h.size; |
| virt_mb(); |
| ring->intf->in_cons = cons; |
| continue; |
| } |
| |
| memcpy(&req->rc, &h, sizeof(h)); |
| req->rc.offset = 0; |
| |
| masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring)); |
| /* Then, read the whole packet (including the header) */ |
| xen_9pfs_read_packet(req->rc.sdata, ring->data.in, h.size, |
| masked_prod, &masked_cons, |
| XEN_9PFS_RING_SIZE(ring)); |
| |
| virt_mb(); |
| cons += h.size; |
| ring->intf->in_cons = cons; |
| |
| status = (req->status != REQ_STATUS_ERROR) ? |
| REQ_STATUS_RCVD : REQ_STATUS_ERROR; |
| |
| p9_client_cb(priv->client, req, status); |
| } |
| } |
| |
| static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r) |
| { |
| struct xen_9pfs_dataring *ring = r; |
| |
| if (!ring || !ring->priv->client) { |
| /* ignore spurious interrupt */ |
| return IRQ_HANDLED; |
| } |
| |
| wake_up_interruptible(&ring->wq); |
| schedule_work(&ring->work); |
| |
| return IRQ_HANDLED; |
| } |
| |
| static struct p9_trans_module p9_xen_trans = { |
| .name = "xen", |
| .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT - 2), |
| .def = 1, |
| .create = p9_xen_create, |
| .close = p9_xen_close, |
| .request = p9_xen_request, |
| .cancel = p9_xen_cancel, |
| .owner = THIS_MODULE, |
| }; |
| |
| static const struct xenbus_device_id xen_9pfs_front_ids[] = { |
| { "9pfs" }, |
| { "" } |
| }; |
| |
| static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) |
| { |
| int i, j; |
| |
| write_lock(&xen_9pfs_lock); |
| list_del(&priv->list); |
| write_unlock(&xen_9pfs_lock); |
| |
| for (i = 0; i < priv->num_rings; i++) { |
| if (!priv->rings[i].intf) |
| break; |
| if (priv->rings[i].irq > 0) |
| unbind_from_irqhandler(priv->rings[i].irq, priv->dev); |
| if (priv->rings[i].data.in) { |
| for (j = 0; |
| j < (1 << priv->rings[i].intf->ring_order); |
| j++) { |
| grant_ref_t ref; |
| |
| ref = priv->rings[i].intf->ref[j]; |
| gnttab_end_foreign_access(ref, NULL); |
| } |
| free_pages_exact(priv->rings[i].data.in, |
| 1UL << (priv->rings[i].intf->ring_order + |
| XEN_PAGE_SHIFT)); |
| } |
| gnttab_end_foreign_access(priv->rings[i].ref, NULL); |
| free_page((unsigned long)priv->rings[i].intf); |
| } |
| kfree(priv->rings); |
| kfree(priv->tag); |
| kfree(priv); |
| } |
| |
| static int xen_9pfs_front_remove(struct xenbus_device *dev) |
| { |
| struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev); |
| |
| dev_set_drvdata(&dev->dev, NULL); |
| xen_9pfs_front_free(priv); |
| return 0; |
| } |
| |
| static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev, |
| struct xen_9pfs_dataring *ring, |
| unsigned int order) |
| { |
| int i = 0; |
| int ret = -ENOMEM; |
| void *bytes = NULL; |
| |
| init_waitqueue_head(&ring->wq); |
| spin_lock_init(&ring->lock); |
| INIT_WORK(&ring->work, p9_xen_response); |
| |
| ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL); |
| if (!ring->intf) |
| return ret; |
| ret = gnttab_grant_foreign_access(dev->otherend_id, |
| virt_to_gfn(ring->intf), 0); |
| if (ret < 0) |
| goto out; |
| ring->ref = ret; |
| bytes = alloc_pages_exact(1UL << (order + XEN_PAGE_SHIFT), |
| GFP_KERNEL | __GFP_ZERO); |
| if (!bytes) { |
| ret = -ENOMEM; |
| goto out; |
| } |
| for (; i < (1 << order); i++) { |
| ret = gnttab_grant_foreign_access( |
| dev->otherend_id, virt_to_gfn(bytes) + i, 0); |
| if (ret < 0) |
| goto out; |
| ring->intf->ref[i] = ret; |
| } |
| ring->intf->ring_order = order; |
| ring->data.in = bytes; |
| ring->data.out = bytes + XEN_FLEX_RING_SIZE(order); |
| |
| ret = xenbus_alloc_evtchn(dev, &ring->evtchn); |
| if (ret) |
| goto out; |
| ring->irq = bind_evtchn_to_irqhandler(ring->evtchn, |
| xen_9pfs_front_event_handler, |
| 0, "xen_9pfs-frontend", ring); |
| if (ring->irq >= 0) |
| return 0; |
| |
| xenbus_free_evtchn(dev, ring->evtchn); |
| ret = ring->irq; |
| out: |
| if (bytes) { |
| for (i--; i >= 0; i--) |
| gnttab_end_foreign_access(ring->intf->ref[i], NULL); |
| free_pages_exact(bytes, 1UL << (order + XEN_PAGE_SHIFT)); |
| } |
| gnttab_end_foreign_access(ring->ref, NULL); |
| free_page((unsigned long)ring->intf); |
| return ret; |
| } |
| |
| static int xen_9pfs_front_probe(struct xenbus_device *dev, |
| const struct xenbus_device_id *id) |
| { |
| int ret, i; |
| struct xenbus_transaction xbt; |
| struct xen_9pfs_front_priv *priv = NULL; |
| char *versions; |
| unsigned int max_rings, max_ring_order, len = 0; |
| |
| versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len); |
| if (IS_ERR(versions)) |
| return PTR_ERR(versions); |
| if (strcmp(versions, "1")) { |
| kfree(versions); |
| return -EINVAL; |
| } |
| kfree(versions); |
| max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0); |
| if (max_rings < XEN_9PFS_NUM_RINGS) |
| return -EINVAL; |
| max_ring_order = xenbus_read_unsigned(dev->otherend, |
| "max-ring-page-order", 0); |
| if (max_ring_order > XEN_9PFS_RING_ORDER) |
| max_ring_order = XEN_9PFS_RING_ORDER; |
| if (p9_xen_trans.maxsize > XEN_FLEX_RING_SIZE(max_ring_order)) |
| p9_xen_trans.maxsize = XEN_FLEX_RING_SIZE(max_ring_order) / 2; |
| |
| priv = kzalloc(sizeof(*priv), GFP_KERNEL); |
| if (!priv) |
| return -ENOMEM; |
| |
| priv->dev = dev; |
| priv->num_rings = XEN_9PFS_NUM_RINGS; |
| priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings), |
| GFP_KERNEL); |
| if (!priv->rings) { |
| kfree(priv); |
| return -ENOMEM; |
| } |
| |
| for (i = 0; i < priv->num_rings; i++) { |
| priv->rings[i].priv = priv; |
| ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i], |
| max_ring_order); |
| if (ret < 0) |
| goto error; |
| } |
| |
| again: |
| ret = xenbus_transaction_start(&xbt); |
| if (ret) { |
| xenbus_dev_fatal(dev, ret, "starting transaction"); |
| goto error; |
| } |
| ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1); |
| if (ret) |
| goto error_xenbus; |
| ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u", |
| priv->num_rings); |
| if (ret) |
| goto error_xenbus; |
| for (i = 0; i < priv->num_rings; i++) { |
| char str[16]; |
| |
| BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9); |
| sprintf(str, "ring-ref%d", i); |
| ret = xenbus_printf(xbt, dev->nodename, str, "%d", |
| priv->rings[i].ref); |
| if (ret) |
| goto error_xenbus; |
| |
| sprintf(str, "event-channel-%d", i); |
| ret = xenbus_printf(xbt, dev->nodename, str, "%u", |
| priv->rings[i].evtchn); |
| if (ret) |
| goto error_xenbus; |
| } |
| priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL); |
| if (IS_ERR(priv->tag)) { |
| ret = PTR_ERR(priv->tag); |
| goto error_xenbus; |
| } |
| ret = xenbus_transaction_end(xbt, 0); |
| if (ret) { |
| if (ret == -EAGAIN) |
| goto again; |
| xenbus_dev_fatal(dev, ret, "completing transaction"); |
| goto error; |
| } |
| |
| write_lock(&xen_9pfs_lock); |
| list_add_tail(&priv->list, &xen_9pfs_devs); |
| write_unlock(&xen_9pfs_lock); |
| dev_set_drvdata(&dev->dev, priv); |
| xenbus_switch_state(dev, XenbusStateInitialised); |
| |
| return 0; |
| |
| error_xenbus: |
| xenbus_transaction_end(xbt, 1); |
| xenbus_dev_fatal(dev, ret, "writing xenstore"); |
| error: |
| dev_set_drvdata(&dev->dev, NULL); |
| xen_9pfs_front_free(priv); |
| return ret; |
| } |
| |
| static int xen_9pfs_front_resume(struct xenbus_device *dev) |
| { |
| dev_warn(&dev->dev, "suspend/resume unsupported\n"); |
| return 0; |
| } |
| |
| static void xen_9pfs_front_changed(struct xenbus_device *dev, |
| enum xenbus_state backend_state) |
| { |
| switch (backend_state) { |
| case XenbusStateReconfiguring: |
| case XenbusStateReconfigured: |
| case XenbusStateInitialising: |
| case XenbusStateInitialised: |
| case XenbusStateUnknown: |
| break; |
| |
| case XenbusStateInitWait: |
| break; |
| |
| case XenbusStateConnected: |
| xenbus_switch_state(dev, XenbusStateConnected); |
| break; |
| |
| case XenbusStateClosed: |
| if (dev->state == XenbusStateClosed) |
| break; |
| fallthrough; /* Missed the backend's CLOSING state */ |
| case XenbusStateClosing: |
| xenbus_frontend_closed(dev); |
| break; |
| } |
| } |
| |
| static struct xenbus_driver xen_9pfs_front_driver = { |
| .ids = xen_9pfs_front_ids, |
| .probe = xen_9pfs_front_probe, |
| .remove = xen_9pfs_front_remove, |
| .resume = xen_9pfs_front_resume, |
| .otherend_changed = xen_9pfs_front_changed, |
| }; |
| |
| static int p9_trans_xen_init(void) |
| { |
| int rc; |
| |
| if (!xen_domain()) |
| return -ENODEV; |
| |
| pr_info("Initialising Xen transport for 9pfs\n"); |
| |
| v9fs_register_trans(&p9_xen_trans); |
| rc = xenbus_register_frontend(&xen_9pfs_front_driver); |
| if (rc) |
| v9fs_unregister_trans(&p9_xen_trans); |
| |
| return rc; |
| } |
| module_init(p9_trans_xen_init); |
| MODULE_ALIAS_9P("xen"); |
| |
| static void p9_trans_xen_exit(void) |
| { |
| v9fs_unregister_trans(&p9_xen_trans); |
| return xenbus_unregister_driver(&xen_9pfs_front_driver); |
| } |
| module_exit(p9_trans_xen_exit); |
| |
| MODULE_ALIAS("xen:9pfs"); |
| MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>"); |
| MODULE_DESCRIPTION("Xen Transport for 9P"); |
| MODULE_LICENSE("GPL"); |