diff options
Diffstat (limited to 'net/9p/trans_xen.c')
| -rw-r--r-- | net/9p/trans_xen.c | 590 |
1 files changed, 590 insertions, 0 deletions
diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c new file mode 100644 index 000000000..da0561708 --- /dev/null +++ b/net/9p/trans_xen.c @@ -0,0 +1,590 @@ +/* + * linux/fs/9p/trans_xen + * + * Xen transport layer. + * + * Copyright (C) 2017 by Stefano Stabellini <stefano@aporeto.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License version 2 + * as published by the Free Software Foundation; or, when distributed + * separately from the Linux kernel or incorporated into other + * software packages, subject to the following license: + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this source file (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, modify, + * merge, publish, distribute, sublicense, and/or sell copies of the Software, + * and to permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + */ + +#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; + } + + if (h.size > req->rc.capacity) { + dev_warn(&priv->dev->dev, + "requested packet size too big: %d for tag %d with capacity %zd\n", + h.size, h.tag, req->rc.capacity); + req->status = REQ_STATUS_ERROR; + goto recv_error; + } + + 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)); + +recv_error: + 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++) { + struct xen_9pfs_dataring *ring = &priv->rings[i]; + + cancel_work_sync(&ring->work); + + 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, 0, 0); + } + 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, 0, 0); + 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], 0, 0); + free_pages_exact(bytes, 1UL << (order + XEN_PAGE_SHIFT)); + } + gnttab_end_foreign_access(ring->ref, 0, 0); + free_page((unsigned long)ring->intf); + return ret; +} + +static int xen_9pfs_front_init(struct xenbus_device *dev) +{ + int ret, i; + struct xenbus_transaction xbt; + struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev); + char *versions, *v; + 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); + for (v = versions; *v; v++) { + if (simple_strtoul(v, &v, 10) == 1) { + v = NULL; + break; + } + } + if (v) { + 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->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; + } + + return 0; + + error_xenbus: + xenbus_transaction_end(xbt, 1); + xenbus_dev_fatal(dev, ret, "writing xenstore"); + error: + xen_9pfs_front_free(priv); + return ret; +} + +static int xen_9pfs_front_probe(struct xenbus_device *dev, + const struct xenbus_device_id *id) +{ + struct xen_9pfs_front_priv *priv = NULL; + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->dev = dev; + dev_set_drvdata(&dev->dev, priv); + + write_lock(&xen_9pfs_lock); + list_add_tail(&priv->list, &xen_9pfs_devs); + write_unlock(&xen_9pfs_lock); + + return 0; +} + +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: + if (!xen_9pfs_front_init(dev)) + xenbus_switch_state(dev, XenbusStateInitialised); + 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); + +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_AUTHOR("Stefano Stabellini <stefano@aporeto.com>"); +MODULE_DESCRIPTION("Xen Transport for 9P"); +MODULE_LICENSE("GPL"); |