host/vhost/mic_vhost.c

/* Copyright (C) 2009 Red Hat, Inc.
 * Copyright (C) 2006 Rusty Russell IBM Corporation
 *
 * Author: Michael S. Tsirkin <mst@redhat.com>
 *
 * (C) Badari Pulavarty pbadari@us.ibm.com 2010 with the following comment.
 * Inspiration, some code, and most witty comments come from
 * Documentation/lguest/lguest.c, by Rusty Russell
 *
 * This work is licensed under the terms of the GNU GPL, version 2.

 * For adapting to MIC
 * (C) Copyright 2012 Intel Corporation
 * Author: Caz Yokoyama <Caz.Yokoyama@intel.com>
 *
 * Generic code for virtio server in host kernel.
 */

#include <linux/version.h>
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,34)) || \
        defined(RHEL_RELEASE_CODE)

#include <linux/eventfd.h>
#ifdef RHEL_RELEASE_CODE
#include <linux/vhost.h>
#else
#include "./linux/vhost.h"
#endif
#include <linux/virtio_net.h>
#include <linux/mm.h>
#include <linux/mmu_context.h>
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/poll.h>
#include <linux/file.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/cgroup.h>

#include <linux/net.h>
#include <linux/if_packet.h>
#include <linux/if_arp.h>

#include <net/sock.h>

#ifndef VIRTIO_RING_F_EVENT_IDX  /* virtio_ring.h of rhel6.0 does not define */
#define VIRTIO_RING_F_EVENT_IDX         29
#endif
#include "vhost.h"
#include "mic/micveth_dma.h"

#define mic_addr_in_host(va, pa) ((u8 *)(va) + (u64)(pa))

enum {
        VHOST_MEMORY_MAX_NREGIONS = 64,
        VHOST_MEMORY_F_LOG = 0x1,
};

#if 0
static unsigned vhost_zcopy_mask __read_mostly;
#endif

static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
                            poll_table *pt)
{
        struct vhost_poll *poll;
        poll = container_of(pt, struct vhost_poll, table);

        poll->wqh = wqh;
        add_wait_queue(wqh, &poll->wait);
}

static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
                             void *key)
{
        struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);

        if (!((unsigned long)key & poll->mask))
                return 0;

        vhost_poll_queue(poll);
        return 0;
}

static void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
{
        INIT_LIST_HEAD(&work->node);
        work->fn = fn;
        init_waitqueue_head(&work->done);
        work->flushing = 0;
        work->queue_seq = work->done_seq = 0;
}

/* Init poll structure */
void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
                     unsigned long mask, struct vhost_dev *dev)
{
        init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
        init_poll_funcptr(&poll->table, vhost_poll_func);
        poll->mask = mask;
        poll->dev = dev;

        vhost_work_init(&poll->work, fn);
}

#if 0
/* Start polling a file. We add ourselves to file's wait queue. The caller must
 * keep a reference to a file until after vhost_poll_stop is called. */
void vhost_poll_start(struct vhost_poll *poll, struct file *file)
{
        unsigned long mask;
        mask = file->f_op->poll(file, &poll->table);
        if (mask)
                vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
}
#endif

/* Stop polling a file. After this function returns, it becomes safe to drop the
 * file reference. You must also flush afterwards. */
void vhost_poll_stop(struct vhost_poll *poll)
{
        remove_wait_queue(poll->wqh, &poll->wait);
}

static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
                                unsigned seq)
{
        int left;
        spin_lock_irq(&dev->work_lock);
        left = seq - work->done_seq;
        spin_unlock_irq(&dev->work_lock);
        return left <= 0;
}

static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
{
        unsigned seq;
        int flushing;

        spin_lock_irq(&dev->work_lock);
        seq = work->queue_seq;
        work->flushing++;
        spin_unlock_irq(&dev->work_lock);
        wait_event(work->done, vhost_work_seq_done(dev, work, seq));
        spin_lock_irq(&dev->work_lock);
        flushing = --work->flushing;
        spin_unlock_irq(&dev->work_lock);
        BUG_ON(flushing < 0);
}

/* Flush any work that has been scheduled. When calling this, don't hold any
 * locks that are also used by the callback. */
void vhost_poll_flush(struct vhost_poll *poll)
{
        vhost_work_flush(poll->dev, &poll->work);
}

static inline void vhost_work_queue(struct vhost_dev *dev,
                                    struct vhost_work *work)
{
        unsigned long flags;

        spin_lock_irqsave(&dev->work_lock, flags);
        if (list_empty(&work->node)) {
                list_add_tail(&work->node, &dev->work_list);
                work->queue_seq++;
                wake_up_process(dev->worker);
        }
        spin_unlock_irqrestore(&dev->work_lock, flags);
}

void vhost_poll_queue(struct vhost_poll *poll)
{
        vhost_work_queue(poll->dev, &poll->work);
}

static void vhost_vq_reset(struct vhost_dev *dev,
                           struct vhost_virtqueue *vq)
{
        vq->num = 1;
        vq->desc = NULL;
        vq->avail = NULL;
        vq->used = NULL;
        vq->last_avail_idx = 0;
        vq->avail_idx = 0;
        vq->last_used_idx = 0;
        vq->signalled_used = 0;
        vq->signalled_used_valid = false;
        vq->used_flags = 0;
        vq->log_used = false;
        vq->log_addr = -1ull;
        vq->vhost_hlen = 0;
        vq->sock_hlen = 0;
        vq->private_data = NULL;
        vq->log_base = NULL;
        vq->error_ctx = NULL;
        vq->error = NULL;
        vq->kick = NULL;
        vq->call_ctx = NULL;
        vq->call = NULL;
        vq->log_ctx = NULL;
        vq->upend_idx = 0;
        vq->done_idx = 0;
        vq->ubufs = NULL;
}

static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
{
        kfree(vq->indirect);
        vq->indirect = NULL;
        kfree(vq->log);
        vq->log = NULL;
        kfree(vq->heads);
        vq->heads = NULL;
        kfree(vq->ubuf_info);
        vq->ubuf_info = NULL;
}

#if 0
void vhost_enable_zcopy(int vq)
{
        vhost_zcopy_mask |= 0x1 << vq;
}
#endif

static void vhost_dev_free_iovecs(struct vhost_dev *dev)
{
        int i;
        for (i = 0; i < dev->nvqs; ++i)
                vhost_vq_free_iovecs(&dev->vqs[i]);
}

long vhost_dev_init(struct vhost_dev *dev,
                    struct vhost_virtqueue *vqs, int nvqs)
{
        int i;

        dev->vqs = vqs;
        dev->nvqs = nvqs;
        mutex_init(&dev->mutex);
        dev->log_ctx = NULL;
        dev->log_file = NULL;
        dev->memory = NULL;
        dev->mm = NULL;
        spin_lock_init(&dev->work_lock);
        INIT_LIST_HEAD(&dev->work_list);
        dev->worker = NULL;

        for (i = 0; i < dev->nvqs; ++i) {
                dev->vqs[i].log = NULL;
                dev->vqs[i].indirect = NULL;
                dev->vqs[i].heads = NULL;
                dev->vqs[i].ubuf_info = NULL;
                dev->vqs[i].dev = dev;
                mutex_init(&dev->vqs[i].mutex);
                vhost_vq_reset(dev, dev->vqs + i);
                if (dev->vqs[i].handle_kick)
                        vhost_poll_init(&dev->vqs[i].poll,
                                        dev->vqs[i].handle_kick, POLLIN, dev);
        }

        return 0;
}

#if 0
/* Caller should have device mutex */
long vhost_dev_check_owner(struct vhost_dev *dev)
{
        /* Are you the owner? If not, I don't think you mean to do that */
        return dev->mm == current->mm ? 0 : -EPERM;
}
#endif

struct vhost_attach_cgroups_struct {
        struct vhost_work work;
        struct task_struct *owner;
        int ret;
};

#if 0
/* Caller should have device mutex */
long vhost_dev_reset_owner(struct vhost_dev *dev)
{
        struct vhost_memory *memory;

        /* Restore memory to default empty mapping. */
        memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
        if (!memory)
                return -ENOMEM;

        vhost_dev_cleanup(dev);

        memory->nregions = 0;
        dev->memory = memory;
        return 0;
}
#endif

/* In case of DMA done not in order in lower device driver for some reason.
 * upend_idx is used to track end of used idx, done_idx is used to track head
 * of used idx. Once lower device DMA done contiguously, we will signal KVM
 * guest used idx.
 */
int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq)
{
        int i;
        int j = 0;

        for (i = vq->done_idx; i != vq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
                if ((vq->heads[i].len == VHOST_DMA_DONE_LEN)) {
                        vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
                        vhost_add_used_and_signal(vq->dev, vq,
                                                  vq->heads[i].id, 0);
                        ++j;
                } else
                        break;
        }
        if (j)
                vq->done_idx = i;
        return j;
}

/* Caller should have device mutex */
void vhost_dev_cleanup(struct vhost_dev *dev)
{
        int i;
        for (i = 0; i < dev->nvqs; ++i) {
                if (dev->vqs[i].kick && dev->vqs[i].handle_kick) {
                        vhost_poll_stop(&dev->vqs[i].poll);
                        vhost_poll_flush(&dev->vqs[i].poll);
                }
                BUG_ON(dev->vqs[i].ubufs != NULL);

                /* Signal guest as appropriate. */
                vhost_zerocopy_signal_used(&dev->vqs[i]);

                if (dev->vqs[i].error_ctx)
                        eventfd_ctx_put(dev->vqs[i].error_ctx);
                if (dev->vqs[i].error)
                        fput(dev->vqs[i].error);
                if (dev->vqs[i].kick)
                        fput(dev->vqs[i].kick);
                if (dev->vqs[i].call_ctx)
                        eventfd_ctx_put(dev->vqs[i].call_ctx);
                if (dev->vqs[i].call)
                        fput(dev->vqs[i].call);
                vhost_vq_reset(dev, dev->vqs + i);
        }
        vhost_dev_free_iovecs(dev);
        if (dev->log_ctx)
                eventfd_ctx_put(dev->log_ctx);
        dev->log_ctx = NULL;
        if (dev->log_file)
                fput(dev->log_file);
        dev->log_file = NULL;
        /* No one will access memory at this point */
        kfree(dev->memory);
        dev->memory = NULL;
        WARN_ON(!list_empty(&dev->work_list));
        if (dev->worker) {
                kthread_stop(dev->worker);
                dev->worker = NULL;
        }
        if (dev->mm)
                mmput(dev->mm);
        dev->mm = NULL;
}

#if 0
/* Caller must have device mutex */
long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
{
        return 0;
}
#endif

static int vhost_update_used_flags(struct vhost_virtqueue *vq)
{
  iowrite16(vq->used_flags, mic_addr_in_host(vq->log_addr, &vq->used->flags));
  return 0;
}

#if 0
int vhost_init_used(struct vhost_virtqueue *vq)
{
        int r;
        if (!vq->private_data)
                return 0;

        r = vhost_update_used_flags(vq);
        if (r)
                return r;
        vq->signalled_used_valid = false;
        vq->last_used_idx = ioread16(mic_addr_in_host(vq->log_addr, &vq->used->idx));
        return 0;
}
#endif

/* Each buffer in the virtqueues is actually a chain of descriptors.  This
 * function returns the next descriptor in the chain,
 * or -1U if we're at the end. */
static unsigned next_desc(struct vring_desc *desc)
{
        unsigned int next;

        /* If this descriptor says it doesn't chain, we're done. */
        if (!(desc->flags & VRING_DESC_F_NEXT))
                return -1U;

        /* Check they're not leading us off end of descriptors. */
        next = desc->next;
        /* Make sure compiler knows to grab that: we don't want it changing! */
        /* We will use the result as an index in an array, so most
         * architectures only need a compiler barrier here. */
        read_barrier_depends();

        return next;
}

/* This looks in the virtqueue and for the first available buffer, and converts
 * it to an iovec for convenient access.  Since descriptors consist of some
 * number of output then some number of input descriptors, it's actually two
 * iovecs, but we pack them into one and note how many of each there were.
 *
 * This function returns the descriptor number found, or vq->num (which is
 * never a valid descriptor number) if none was found.  A negative code is
 * returned on error. */
int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
                      struct iovec iov[], unsigned int iov_size,
                      unsigned int *out_num, unsigned int *in_num,
                      struct vhost_log *log, unsigned int *log_num)
{
        struct vring_desc desc;
        unsigned int i, head, found = 0;
        u16 last_avail_idx;
        int ret;

        /* Check it isn't doing very strange things with descriptor numbers. */
        last_avail_idx = vq->last_avail_idx;
        vq->avail_idx = ioread16(mic_addr_in_host(vq->log_addr, &vq->avail->idx));

        if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
                vq_err(vq, "Guest moved used index from %u to %u",
                       last_avail_idx, vq->avail_idx);
                return -EFAULT;
        }

        /* If there's nothing new since last we looked, return invalid. */
        if (vq->avail_idx == last_avail_idx)
                return vq->num;

        /* Only get avail ring entries after they have been exposed by guest. */
        smp_rmb();

        /* Grab the next descriptor number they're advertising, and increment
         * the index we've seen. */
        head = ioread16(mic_addr_in_host(vq->log_addr,
                                                                         &vq->avail->ring[last_avail_idx % vq->num]));

        /* If their number is silly, that's an error. */
        if (unlikely(head >= vq->num)) {
                vq_err(vq, "Guest says index %u > %u is available",
                       head, vq->num);
                return -EINVAL;
        }

        /* When we start there are none of either input nor output. */
        *out_num = *in_num = 0;
        if (unlikely(log))
                *log_num = 0;

        i = head;
        do {
                unsigned iov_count = *in_num + *out_num;
                if (unlikely(i >= vq->num)) {
                        vq_err(vq, "Desc index is %u > %u, head = %u",
                               i, vq->num, head);
                        return -EINVAL;
                }
                if (unlikely(++found > vq->num)) {
                        vq_err(vq, "Loop detected: last one at %u "
                               "vq size %u head %u\n",
                               i, vq->num, head);
                        return -EINVAL;
                }
                memcpy_fromio(&desc, mic_addr_in_host(vq->log_addr, vq->desc + i), sizeof(desc));

                (iov + iov_count)->iov_base = (void *)desc.addr;
                (iov + iov_count)->iov_len = desc.len;
                ret = 1;
                if (desc.flags & VRING_DESC_F_WRITE) {
                        /* If this is an input descriptor,
                         * increment that count. */
                        *in_num += ret;
                        if (unlikely(log)) {
                                log[*log_num].addr = desc.addr;
                                log[*log_num].len = desc.len;
                                ++*log_num;
                        }
                } else {
                        /* If it's an output descriptor, they're all supposed
                         * to come before any input descriptors. */
                        if (unlikely(*in_num)) {
                                vq_err(vq, "Descriptor has out after in: "
                                       "idx %d\n", i);
                                return -EINVAL;
                        }
                        *out_num += ret;
                }
        } while ((i = next_desc(&desc)) != -1);

        /* On success, increment avail index. */
        vq->last_avail_idx++;

        /* Assume notifications from guest are disabled at this point,
         * if they aren't we would need to update avail_event index. */
        BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
        return head;
}

/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
{
        vq->last_avail_idx -= n;
}

/* After we've used one of their buffers, we tell them about it.  We'll then
 * want to notify the guest, using eventfd. */
int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
{
        struct vring_used_elem __user *used;

        /* The virtqueue contains a ring of used buffers.  Get a pointer to the
         * next entry in that used ring. */
        used = &vq->used->ring[vq->last_used_idx % vq->num];
        iowrite16(head, mic_addr_in_host(vq->log_addr, &used->id));
        iowrite16(len, mic_addr_in_host(vq->log_addr, &used->len));
        /* Make sure buffer is written before we update index. */
        smp_wmb();
        ioread16(mic_addr_in_host(vq->log_addr, &used->id));
        iowrite16(vq->last_used_idx + 1, mic_addr_in_host(vq->log_addr, &vq->used->idx));

        vq->last_used_idx++;

        /* If the driver never bothers to signal in a very long while,
         * used index might wrap around. If that happens, invalidate
         * signalled_used index we stored. TODO: make sure driver
         * signals at least once in 2^16 and remove this. */
        if (unlikely(vq->last_used_idx == vq->signalled_used))
                vq->signalled_used_valid = false;
        return 0;
}

static int __vhost_add_used_n(struct vhost_virtqueue *vq,
                            struct vring_used_elem *heads,
                            unsigned count)
{
        struct vring_used_elem __user *used;
        u16 old, new;
        int start;

        start = vq->last_used_idx % vq->num;
        used = vq->used->ring + start;
        memcpy_toio(mic_addr_in_host(vq->log_addr, used), heads, count * sizeof(*used));
        old = vq->last_used_idx;
        new = (vq->last_used_idx += count);
        /* If the driver never bothers to signal in a very long while,
         * used index might wrap around. If that happens, invalidate
         * signalled_used index we stored. TODO: make sure driver
         * signals at least once in 2^16 and remove this. */
        if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
                vq->signalled_used_valid = false;
        return 0;
}

/* After we've used one of their buffers, we tell them about it.  We'll then
 * want to notify the guest, using eventfd. */
int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
                     unsigned count)
{
        int start, n, r;

        start = vq->last_used_idx % vq->num;
        n = vq->num - start;
        if (n < count) {
                r = __vhost_add_used_n(vq, heads, n);
                if (r < 0)
                        return r;
                heads += n;
                count -= n;
        }
        r = __vhost_add_used_n(vq, heads, count);

        /* Make sure buffer is written before we update index. */
        smp_wmb();
        iowrite16(vq->last_used_idx, mic_addr_in_host(vq->log_addr, &vq->used->idx));
        return r;
}

static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
        __u16 old, new;
        bool v;
        /* Flush out used index updates. This is paired
         * with the barrier that the Guest executes when enabling
         * interrupts. */
        smp_mb();

        if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
            unlikely(vq->avail_idx == vq->last_avail_idx))
                return true;

        if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
                __u16 flags;
                flags = ioread16(mic_addr_in_host(vq->log_addr, &vq->avail->flags));
                return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
        }
        old = vq->signalled_used;
        v = vq->signalled_used_valid;
        new = vq->signalled_used = vq->last_used_idx;
        vq->signalled_used_valid = true;

        if (unlikely(!v))
                return true;

        return false;
}

/* This actually signals the guest, using eventfd. */
void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
        /* Signal the Guest tell them we used something up. */
        if (vq->log_base && vhost_notify(dev, vq))
                mic_send_virtio_intr((struct _mic_ctx_t *)vq->log_base);
}

/* And here's the combo meal deal.  Supersize me! */
void vhost_add_used_and_signal(struct vhost_dev *dev,
                               struct vhost_virtqueue *vq,
                               unsigned int head, int len)
{
        vhost_add_used(vq, head, len);
        vhost_signal(dev, vq);
}

#if 0
/* multi-buffer version of vhost_add_used_and_signal */
void vhost_add_used_and_signal_n(struct vhost_dev *dev,
                                 struct vhost_virtqueue *vq,
                                 struct vring_used_elem *heads, unsigned count)
{
        vhost_add_used_n(vq, heads, count);
        vhost_signal(dev, vq);
}
#endif

/* OK, now we need to know about added descriptors. */
bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
        u16 avail_idx;
        int r;
        if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
                return false;
        vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
        if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
                r = vhost_update_used_flags(vq);
                if (r) {
                        vq_err(vq, "Failed to enable notification at %p: %d\n",
                               &vq->used->flags, r);
                        return false;
                }
        }
        /* They could have slipped one in as we were doing that: make
         * sure it's written, then check again. */
        smp_mb();
        avail_idx = ioread16(mic_addr_in_host(vq->log_addr, &vq->avail->idx));

        return avail_idx != vq->avail_idx;
}

/* We don't need to be notified again. */
void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
        int r;
        if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
                return;
        vq->used_flags |= VRING_USED_F_NO_NOTIFY;
        if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
                r = vhost_update_used_flags(vq);
                if (r)
                        vq_err(vq, "Failed to enable notification at %p: %d\n",
                               &vq->used->flags, r);
        }
}
#endif