From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753408AbZI0Hpd (ORCPT ); Sun, 27 Sep 2009 03:45:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753371AbZI0Hpb (ORCPT ); Sun, 27 Sep 2009 03:45:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45617 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753299AbZI0Hp2 (ORCPT ); Sun, 27 Sep 2009 03:45:28 -0400 Date: Sun, 27 Sep 2009 09:43:03 +0200 From: "Michael S. Tsirkin" To: "Ira W. Snyder" Cc: netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu, linux-mm@kvack.org, akpm@linux-foundation.org, hpa@zytor.com, gregory.haskins@gmail.com, Rusty Russell , s.hetze@linux-ag.com Subject: Re: [PATCHv5 3/3] vhost_net: a kernel-level virtio server Message-ID: <20090927074302.GA3690@redhat.com> References: <20090827160750.GD23722@redhat.com> <20090925170158.GA16014@ovro.caltech.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090925170158.GA16014@ovro.caltech.edu> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 25, 2009 at 10:01:58AM -0700, Ira W. Snyder wrote: > > + case VHOST_SET_VRING_KICK: > > + r = copy_from_user(&f, argp, sizeof f); > > + if (r < 0) > > + break; > > + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); > > + if (IS_ERR(eventfp)) > > + return PTR_ERR(eventfp); > > + if (eventfp != vq->kick) { > > + pollstop = filep = vq->kick; > > + pollstart = vq->kick = eventfp; > > + } else > > + filep = eventfp; > > + break; > > + case VHOST_SET_VRING_CALL: > > + r = copy_from_user(&f, argp, sizeof f); > > + if (r < 0) > > + break; > > + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); > > + if (IS_ERR(eventfp)) > > + return PTR_ERR(eventfp); > > + if (eventfp != vq->call) { > > + filep = vq->call; > > + ctx = vq->call_ctx; > > + vq->call = eventfp; > > + vq->call_ctx = eventfp ? > > + eventfd_ctx_fileget(eventfp) : NULL; > > + } else > > + filep = eventfp; > > + break; > > + case VHOST_SET_VRING_ERR: > > + r = copy_from_user(&f, argp, sizeof f); > > + if (r < 0) > > + break; > > + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); > > + if (IS_ERR(eventfp)) > > + return PTR_ERR(eventfp); > > + if (eventfp != vq->error) { > > + filep = vq->error; > > + vq->error = eventfp; > > + ctx = vq->error_ctx; > > + vq->error_ctx = eventfp ? > > + eventfd_ctx_fileget(eventfp) : NULL; > > + } else > > + filep = eventfp; > > + break; > > I'm not sure how these eventfd's save a trip to userspace. > > AFAICT, eventfd's cannot be used to signal another part of the kernel, > they can only be used to wake up userspace. Yes, they can. See irqfd code in virt/kvm/eventfd.c. > In my system, when an IRQ for kick() comes in, I have an eventfd which > gets signalled to notify userspace. When I want to send a call(), I have > to use a special ioctl(), just like lguest does. > > Doesn't this mean that for call(), vhost is just going to signal an > eventfd to wake up userspace, which is then going to call ioctl(), and > then we're back in kernelspace. Seems like a wasted userspace > round-trip. > > Or am I mis-reading this code? Yes. Kernel can poll eventfd and deliver an interrupt directly without involving userspace. > PS - you can see my current code at: > http://www.mmarray.org/~iws/virtio-phys/ > > Thanks, > Ira > > > + default: > > + r = -ENOIOCTLCMD; > > + } > > + > > + if (pollstop && vq->handle_kick) > > + vhost_poll_stop(&vq->poll); > > + > > + if (ctx) > > + eventfd_ctx_put(ctx); > > + if (filep) > > + fput(filep); > > + > > + if (pollstart && vq->handle_kick) > > + vhost_poll_start(&vq->poll, vq->kick); > > + > > + mutex_unlock(&vq->mutex); > > + > > + if (pollstop && vq->handle_kick) > > + vhost_poll_flush(&vq->poll); > > + return 0; > > +} > > + > > +long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg) > > +{ > > + void __user *argp = (void __user *)arg; > > + long r; > > + > > + mutex_lock(&d->mutex); > > + /* If you are not the owner, you can become one */ > > + if (ioctl == VHOST_SET_OWNER) { > > + r = vhost_dev_set_owner(d); > > + goto done; > > + } > > + > > + /* You must be the owner to do anything else */ > > + r = vhost_dev_check_owner(d); > > + if (r) > > + goto done; > > + > > + switch (ioctl) { > > + case VHOST_SET_MEM_TABLE: > > + r = vhost_set_memory(d, argp); > > + break; > > + default: > > + r = vhost_set_vring(d, ioctl, argp); > > + break; > > + } > > +done: > > + mutex_unlock(&d->mutex); > > + return r; > > +} > > + > > +static const struct vhost_memory_region *find_region(struct vhost_memory *mem, > > + __u64 addr, __u32 len) > > +{ > > + struct vhost_memory_region *reg; > > + int i; > > + /* linear search is not brilliant, but we really have on the order of 6 > > + * regions in practice */ > > + for (i = 0; i < mem->nregions; ++i) { > > + reg = mem->regions + i; > > + if (reg->guest_phys_addr <= addr && > > + reg->guest_phys_addr + reg->memory_size - 1 >= addr) > > + return reg; > > + } > > + return NULL; > > +} > > + > > +int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, > > + struct iovec iov[], int iov_size) > > +{ > > + const struct vhost_memory_region *reg; > > + struct vhost_memory *mem; > > + struct iovec *_iov; > > + u64 s = 0; > > + int ret = 0; > > + > > + rcu_read_lock(); > > + > > + mem = rcu_dereference(dev->memory); > > + while ((u64)len > s) { > > + u64 size; > > + if (ret >= iov_size) { > > + ret = -ENOBUFS; > > + break; > > + } > > + reg = find_region(mem, addr, len); > > + if (!reg) { > > + ret = -EFAULT; > > + break; > > + } > > + _iov = iov + ret; > > + size = reg->memory_size - addr + reg->guest_phys_addr; > > + _iov->iov_len = min((u64)len, size); > > + _iov->iov_base = (void *) > > + (reg->userspace_addr + addr - reg->guest_phys_addr); > > + s += size; > > + addr += size; > > + ++ret; > > + } > > + > > + rcu_read_unlock(); > > + return ret; > > +} > > + > > +/* Each buffer in the virtqueues is actually a chain of descriptors. This > > + * function returns the next descriptor in the chain, or vq->vring.num if we're > > + * at the end. */ > > +static unsigned next_desc(struct vhost_virtqueue *vq, 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 vq->num; > > + > > + /* 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(); > > + > > + if (next >= vq->num) { > > + vq_err(vq, "Desc next is %u > %u", next, vq->num); > > + return vq->num; > > + } > > + > > + 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. */ > > +unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, > > + struct iovec iov[], > > + unsigned int *out_num, unsigned int *in_num) > > +{ > > + struct vring_desc desc; > > + unsigned int i, head; > > + u16 last_avail_idx; > > + int ret; > > + > > + /* Check it isn't doing very strange things with descriptor numbers. */ > > + last_avail_idx = vq->last_avail_idx; > > + if (get_user(vq->avail_idx, &vq->avail->idx)) { > > + vq_err(vq, "Failed to access avail idx at %p\n", > > + &vq->avail->idx); > > + return vq->num; > > + } > > + > > + if ((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 vq->num; > > + } > > + > > + /* If there's nothing new since last we looked, return invalid. */ > > + if (vq->avail_idx == last_avail_idx) > > + return vq->num; > > + > > + /* Grab the next descriptor number they're advertising, and increment > > + * the index we've seen. */ > > + if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) { > > + vq_err(vq, "Failed to read head: idx %d address %p\n", > > + last_avail_idx, > > + &vq->avail->ring[last_avail_idx % vq->num]); > > + return vq->num; > > + } > > + > > + /* If their number is silly, that's an error. */ > > + if (head >= vq->num) { > > + vq_err(vq, "Guest says index %u > %u is available", > > + head, vq->num); > > + return vq->num; > > + } > > + > > + vq->last_avail_idx++; > > + > > + /* When we start there are none of either input nor output. */ > > + *out_num = *in_num = 0; > > + > > + i = head; > > + do { > > + unsigned iov_count = *in_num + *out_num; > > + if (copy_from_user(&desc, vq->desc + i, sizeof desc)) { > > + vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", > > + i, vq->desc + i); > > + return vq->num; > > + } > > + ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, > > + VHOST_NET_MAX_SG - iov_count); > > + if (ret < 0) { > > + vq_err(vq, "Translation failure %d descriptor idx %d\n", > > + ret, i); > > + return vq->num; > > + } > > + /* If this is an input descriptor, increment that count. */ > > + if (desc.flags & VRING_DESC_F_WRITE) > > + *in_num += ret; > > + else { > > + /* If it's an output descriptor, they're all supposed > > + * to come before any input descriptors. */ > > + if (*in_num) { > > + vq_err(vq, "Descriptor has out after in: " > > + "idx %d\n", i); > > + return vq->num; > > + } > > + *out_num += ret; > > + } > > + } while ((i = next_desc(vq, &desc)) != vq->num); > > + return head; > > +} > > + > > +/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ > > +void vhost_discard_vq_desc(struct vhost_virtqueue *vq) > > +{ > > + vq->last_avail_idx--; > > +} > > + > > +/* After we've used one of their buffers, we tell them about it. We'll then > > + * want to send them an interrupt, using vq->call. */ > > +int vhost_add_used(struct vhost_virtqueue *vq, > > + unsigned int head, int len) > > +{ > > + struct vring_used_elem *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]; > > + if (put_user(head, &used->id)) { > > + vq_err(vq, "Failed to write used id"); > > + return -EFAULT; > > + } > > + if (put_user(len, &used->len)) { > > + vq_err(vq, "Failed to write used len"); > > + return -EFAULT; > > + } > > + /* Make sure buffer is written before we update index. */ > > + wmb(); > > + if (put_user(vq->last_used_idx + 1, &vq->used->idx)) { > > + vq_err(vq, "Failed to increment used idx"); > > + return -EFAULT; > > + } > > + vq->last_used_idx++; > > + return 0; > > +} > > + > > +/* This actually sends the interrupt for this virtqueue */ > > +void vhost_trigger_irq(struct vhost_dev *dev, struct vhost_virtqueue *vq) > > +{ > > + __u16 flags = 0; > > + if (get_user(flags, &vq->avail->flags)) { > > + vq_err(vq, "Failed to get flags"); > > + return; > > + } > > + > > + /* If they don't want an interrupt, don't send one, unless empty. */ > > + if ((flags & VRING_AVAIL_F_NO_INTERRUPT) && > > + (!vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) || > > + vq->avail_idx != vq->last_avail_idx)) > > + return; > > + > > + /* Send the Guest an interrupt tell them we used something up. */ > > + if (vq->call_ctx) > > + eventfd_signal(vq->call_ctx, 1); > > +} > > + > > +/* And here's the combo meal deal. Supersize me! */ > > +void vhost_add_used_and_trigger(struct vhost_dev *dev, > > + struct vhost_virtqueue *vq, > > + unsigned int head, int len) > > +{ > > + vhost_add_used(vq, head, len); > > + vhost_trigger_irq(dev, vq); > > +} > > + > > +/* OK, now we need to know about added descriptors. */ > > +bool vhost_notify(struct vhost_virtqueue *vq) > > +{ > > + int r; > > + if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) > > + return false; > > + vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; > > + r = put_user(vq->used_flags, &vq->used->flags); > > + if (r) > > + vq_err(vq, "Failed to disable notification: %d\n", r); > > + /* They could have slipped one in as we were doing that: make > > + * sure it's written, tell caller it needs to check again. */ > > + mb(); > > + return true; > > +} > > + > > +/* We don't need to be notified again. */ > > +void vhost_no_notify(struct vhost_virtqueue *vq) > > +{ > > + int r; > > + if (vq->used_flags & VRING_USED_F_NO_NOTIFY) > > + return; > > + vq->used_flags |= VRING_USED_F_NO_NOTIFY; > > + r = put_user(vq->used_flags, &vq->used->flags); > > + if (r) > > + vq_err(vq, "Failed to enable notification: %d\n", r); > > +} > > + > > +int vhost_init(void) > > +{ > > + vhost_workqueue = create_workqueue("vhost"); > > + if (!vhost_workqueue) > > + return -ENOMEM; > > + return 0; > > +} > > + > > +void vhost_cleanup(void) > > +{ > > + destroy_workqueue(vhost_workqueue); > > +} > > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > > new file mode 100644 > > index 0000000..8e13d06 > > --- /dev/null > > +++ b/drivers/vhost/vhost.h > > @@ -0,0 +1,122 @@ > > +#ifndef _VHOST_H > > +#define _VHOST_H > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +struct vhost_device; > > + > > +enum { > > + VHOST_NET_MAX_SG = MAX_SKB_FRAGS + 2, > > +}; > > + > > +/* Poll a file (eventfd or socket) */ > > +/* Note: there's nothing vhost specific about this structure. */ > > +struct vhost_poll { > > + poll_table table; > > + wait_queue_head_t *wqh; > > + wait_queue_t wait; > > + /* struct which will handle all actual work. */ > > + struct work_struct work; > > + unsigned long mask; > > +}; > > + > > +void vhost_poll_init(struct vhost_poll *poll, work_func_t func, > > + unsigned long mask); > > +void vhost_poll_start(struct vhost_poll *poll, struct file *file); > > +void vhost_poll_stop(struct vhost_poll *poll); > > +void vhost_poll_flush(struct vhost_poll *poll); > > + > > +/* The virtqueue structure describes a queue attached to a device. */ > > +struct vhost_virtqueue { > > + struct vhost_dev *dev; > > + > > + /* The actual ring of buffers. */ > > + struct mutex mutex; > > + unsigned int num; > > + struct vring_desc __user *desc; > > + struct vring_avail __user *avail; > > + struct vring_used __user *used; > > + struct file *kick; > > + struct file *call; > > + struct file *error; > > + struct eventfd_ctx *call_ctx; > > + struct eventfd_ctx *error_ctx; > > + > > + struct vhost_poll poll; > > + > > + /* The routine to call when the Guest pings us, or timeout. */ > > + work_func_t handle_kick; > > + > > + /* Last available index we saw. */ > > + u16 last_avail_idx; > > + > > + /* Caches available index value from user. */ > > + u16 avail_idx; > > + > > + /* Last index we used. */ > > + u16 last_used_idx; > > + > > + /* Used flags */ > > + u16 used_flags; > > + > > + struct iovec iov[VHOST_NET_MAX_SG]; > > + struct iovec hdr[VHOST_NET_MAX_SG]; > > +}; > > + > > +struct vhost_dev { > > + /* Readers use RCU to access memory table pointer. > > + * Writers use mutex below.*/ > > + struct vhost_memory *memory; > > + struct mm_struct *mm; > > + struct vhost_virtqueue *vqs; > > + int nvqs; > > + struct mutex mutex; > > + unsigned acked_features; > > +}; > > + > > +long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs); > > +long vhost_dev_check_owner(struct vhost_dev *); > > +long vhost_dev_reset_owner(struct vhost_dev *); > > +void vhost_dev_cleanup(struct vhost_dev *); > > +long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg); > > + > > +unsigned vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *, > > + struct iovec iov[], > > + unsigned int *out_num, unsigned int *in_num); > > +void vhost_discard_vq_desc(struct vhost_virtqueue *); > > + > > +int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len); > > +void vhost_trigger_irq(struct vhost_dev *, struct vhost_virtqueue *); > > +void vhost_add_used_and_trigger(struct vhost_dev *, struct vhost_virtqueue *, > > + unsigned int head, int len); > > +void vhost_no_notify(struct vhost_virtqueue *); > > +bool vhost_notify(struct vhost_virtqueue *); > > + > > +int vhost_init(void); > > +void vhost_cleanup(void); > > + > > +#define vq_err(vq, fmt, ...) do { \ > > + pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ > > + if ((vq)->error_ctx) \ > > + eventfd_signal((vq)->error_ctx, 1);\ > > + } while (0) > > + > > +enum { > > + VHOST_FEATURES = 1 << VIRTIO_F_NOTIFY_ON_EMPTY, > > +}; > > + > > +static inline int vhost_has_feature(struct vhost_dev *dev, int bit) > > +{ > > + return dev->acked_features & (1 << bit); > > +} > > + > > +#endif > > diff --git a/include/linux/Kbuild b/include/linux/Kbuild > > index dec2f18..975df9a 100644 > > --- a/include/linux/Kbuild > > +++ b/include/linux/Kbuild > > @@ -360,6 +360,7 @@ unifdef-y += uio.h > > unifdef-y += unistd.h > > unifdef-y += usbdevice_fs.h > > unifdef-y += utsname.h > > +unifdef-y += vhost.h > > unifdef-y += videodev2.h > > unifdef-y += videodev.h > > unifdef-y += virtio_config.h > > diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h > > index 0521177..781a8bb 100644 > > --- a/include/linux/miscdevice.h > > +++ b/include/linux/miscdevice.h > > @@ -30,6 +30,7 @@ > > #define HPET_MINOR 228 > > #define FUSE_MINOR 229 > > #define KVM_MINOR 232 > > +#define VHOST_NET_MINOR 233 > > #define MISC_DYNAMIC_MINOR 255 > > > > struct device; > > diff --git a/include/linux/vhost.h b/include/linux/vhost.h > > new file mode 100644 > > index 0000000..3f441a9 > > --- /dev/null > > +++ b/include/linux/vhost.h > > @@ -0,0 +1,101 @@ > > +#ifndef _LINUX_VHOST_H > > +#define _LINUX_VHOST_H > > +/* Userspace interface for in-kernel virtio accelerators. */ > > + > > +/* vhost is used to reduce the number of system calls involved in virtio. > > + * > > + * Existing virtio net code is used in the guest without modification. > > + * > > + * This header includes interface used by userspace hypervisor for > > + * device configuration. > > + */ > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +struct vhost_vring_state { > > + unsigned int index; > > + unsigned int num; > > +}; > > + > > +struct vhost_vring_file { > > + unsigned int index; > > + int fd; > > +}; > > + > > +struct vhost_vring_addr { > > + unsigned int index; > > + unsigned int padding; > > + __u64 user_addr; > > +}; > > + > > +struct vhost_memory_region { > > + __u64 guest_phys_addr; > > + __u64 memory_size; /* bytes */ > > + __u64 userspace_addr; > > + __u64 padding; /* read/write protection? */ > > +}; > > + > > +struct vhost_memory { > > + __u32 nregions; > > + __u32 padding; > > + struct vhost_memory_region regions[0]; > > +}; > > + > > +/* ioctls */ > > + > > +#define VHOST_VIRTIO 0xAF > > + > > +/* Features bitmask for forward compatibility. Transport bits are used for > > + * vhost specific features. */ > > +#define VHOST_GET_FEATURES _IOR(VHOST_VIRTIO, 0x00, __u64) > > +#define VHOST_ACK_FEATURES _IOW(VHOST_VIRTIO, 0x00, __u64) > > + > > +/* Set current process as the (exclusive) owner of this file descriptor. This > > + * must be called before any other vhost command. Further calls to > > + * VHOST_OWNER_SET fail until VHOST_OWNER_RESET is called. */ > > +#define VHOST_SET_OWNER _IO(VHOST_VIRTIO, 0x01) > > +/* Give up ownership, and reset the device to default values. > > + * Allows subsequent call to VHOST_OWNER_SET to succeed. */ > > +#define VHOST_RESET_OWNER _IO(VHOST_VIRTIO, 0x02) > > + > > +/* Set up/modify memory layout */ > > +#define VHOST_SET_MEM_TABLE _IOW(VHOST_VIRTIO, 0x03, struct vhost_memory) > > + > > +/* Ring setup. These parameters can not be modified while ring is running > > + * (bound to a device). */ > > +/* Set number of descriptors in ring */ > > +#define VHOST_SET_VRING_NUM _IOW(VHOST_VIRTIO, 0x10, struct vhost_vring_state) > > +/* Start of array of descriptors (virtually contiguous) */ > > +#define VHOST_SET_VRING_DESC _IOW(VHOST_VIRTIO, 0x11, struct vhost_vring_addr) > > +/* Used structure address */ > > +#define VHOST_SET_VRING_USED _IOW(VHOST_VIRTIO, 0x12, struct vhost_vring_addr) > > +/* Available structure address */ > > +#define VHOST_SET_VRING_AVAIL _IOW(VHOST_VIRTIO, 0x13, struct vhost_vring_addr) > > +/* Base value where queue looks for available descriptors */ > > +#define VHOST_SET_VRING_BASE _IOW(VHOST_VIRTIO, 0x14, struct vhost_vring_state) > > +/* Get accessor: reads index, writes value in num */ > > +#define VHOST_GET_VRING_BASE _IOWR(VHOST_VIRTIO, 0x14, struct vhost_vring_state) > > + > > +/* The following ioctls use eventfd file descriptors to signal and poll > > + * for events. */ > > + > > +/* Set eventfd to poll for added buffers */ > > +#define VHOST_SET_VRING_KICK _IOW(VHOST_VIRTIO, 0x20, struct vhost_vring_file) > > +/* Set eventfd to signal when buffers have beed used */ > > +#define VHOST_SET_VRING_CALL _IOW(VHOST_VIRTIO, 0x21, struct vhost_vring_file) > > +/* Set eventfd to signal an error */ > > +#define VHOST_SET_VRING_ERR _IOW(VHOST_VIRTIO, 0x22, struct vhost_vring_file) > > + > > +/* VHOST_NET specific defines */ > > + > > +/* Attach virtio net device to a raw socket. The socket must be already > > + * bound to an ethernet device, this device will be used for transmit. > > + * Pass -1 to unbind from the socket and the transmit device. > > + * This can be used to stop the device (e.g. for migration). */ > > +#define VHOST_NET_SET_SOCKET _IOW(VHOST_VIRTIO, 0x30, int) > > + > > +#endif > > -- > > 1.6.2.5 > > -- > > To unsubscribe from this list: send the line "unsubscribe netdev" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCHv5 3/3] vhost_net: a kernel-level virtio server Date: Sun, 27 Sep 2009 09:43:03 +0200 Message-ID: <20090927074302.GA3690@redhat.com> References: <20090827160750.GD23722@redhat.com> <20090925170158.GA16014@ovro.caltech.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu, linux-mm@kvack.org, akpm@linux-foundation.org, hpa@zytor.com, gregory.haskins@gmail.com, Rusty Russell , s.hetze@linux-ag.com To: "Ira W. Snyder" Return-path: Content-Disposition: inline In-Reply-To: <20090925170158.GA16014@ovro.caltech.edu> Sender: owner-linux-mm@kvack.org List-Id: netdev.vger.kernel.org On Fri, Sep 25, 2009 at 10:01:58AM -0700, Ira W. Snyder wrote: > > + case VHOST_SET_VRING_KICK: > > + r = copy_from_user(&f, argp, sizeof f); > > + if (r < 0) > > + break; > > + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); > > + if (IS_ERR(eventfp)) > > + return PTR_ERR(eventfp); > > + if (eventfp != vq->kick) { > > + pollstop = filep = vq->kick; > > + pollstart = vq->kick = eventfp; > > + } else > > + filep = eventfp; > > + break; > > + case VHOST_SET_VRING_CALL: > > + r = copy_from_user(&f, argp, sizeof f); > > + if (r < 0) > > + break; > > + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); > > + if (IS_ERR(eventfp)) > > + return PTR_ERR(eventfp); > > + if (eventfp != vq->call) { > > + filep = vq->call; > > + ctx = vq->call_ctx; > > + vq->call = eventfp; > > + vq->call_ctx = eventfp ? > > + eventfd_ctx_fileget(eventfp) : NULL; > > + } else > > + filep = eventfp; > > + break; > > + case VHOST_SET_VRING_ERR: > > + r = copy_from_user(&f, argp, sizeof f); > > + if (r < 0) > > + break; > > + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); > > + if (IS_ERR(eventfp)) > > + return PTR_ERR(eventfp); > > + if (eventfp != vq->error) { > > + filep = vq->error; > > + vq->error = eventfp; > > + ctx = vq->error_ctx; > > + vq->error_ctx = eventfp ? > > + eventfd_ctx_fileget(eventfp) : NULL; > > + } else > > + filep = eventfp; > > + break; > > I'm not sure how these eventfd's save a trip to userspace. > > AFAICT, eventfd's cannot be used to signal another part of the kernel, > they can only be used to wake up userspace. Yes, they can. See irqfd code in virt/kvm/eventfd.c. > In my system, when an IRQ for kick() comes in, I have an eventfd which > gets signalled to notify userspace. When I want to send a call(), I have > to use a special ioctl(), just like lguest does. > > Doesn't this mean that for call(), vhost is just going to signal an > eventfd to wake up userspace, which is then going to call ioctl(), and > then we're back in kernelspace. Seems like a wasted userspace > round-trip. > > Or am I mis-reading this code? Yes. Kernel can poll eventfd and deliver an interrupt directly without involving userspace. > PS - you can see my current code at: > http://www.mmarray.org/~iws/virtio-phys/ > > Thanks, > Ira > > > + default: > > + r = -ENOIOCTLCMD; > > + } > > + > > + if (pollstop && vq->handle_kick) > > + vhost_poll_stop(&vq->poll); > > + > > + if (ctx) > > + eventfd_ctx_put(ctx); > > + if (filep) > > + fput(filep); > > + > > + if (pollstart && vq->handle_kick) > > + vhost_poll_start(&vq->poll, vq->kick); > > + > > + mutex_unlock(&vq->mutex); > > + > > + if (pollstop && vq->handle_kick) > > + vhost_poll_flush(&vq->poll); > > + return 0; > > +} > > + > > +long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg) > > +{ > > + void __user *argp = (void __user *)arg; > > + long r; > > + > > + mutex_lock(&d->mutex); > > + /* If you are not the owner, you can become one */ > > + if (ioctl == VHOST_SET_OWNER) { > > + r = vhost_dev_set_owner(d); > > + goto done; > > + } > > + > > + /* You must be the owner to do anything else */ > > + r = vhost_dev_check_owner(d); > > + if (r) > > + goto done; > > + > > + switch (ioctl) { > > + case VHOST_SET_MEM_TABLE: > > + r = vhost_set_memory(d, argp); > > + break; > > + default: > > + r = vhost_set_vring(d, ioctl, argp); > > + break; > > + } > > +done: > > + mutex_unlock(&d->mutex); > > + return r; > > +} > > + > > +static const struct vhost_memory_region *find_region(struct vhost_memory *mem, > > + __u64 addr, __u32 len) > > +{ > > + struct vhost_memory_region *reg; > > + int i; > > + /* linear search is not brilliant, but we really have on the order of 6 > > + * regions in practice */ > > + for (i = 0; i < mem->nregions; ++i) { > > + reg = mem->regions + i; > > + if (reg->guest_phys_addr <= addr && > > + reg->guest_phys_addr + reg->memory_size - 1 >= addr) > > + return reg; > > + } > > + return NULL; > > +} > > + > > +int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, > > + struct iovec iov[], int iov_size) > > +{ > > + const struct vhost_memory_region *reg; > > + struct vhost_memory *mem; > > + struct iovec *_iov; > > + u64 s = 0; > > + int ret = 0; > > + > > + rcu_read_lock(); > > + > > + mem = rcu_dereference(dev->memory); > > + while ((u64)len > s) { > > + u64 size; > > + if (ret >= iov_size) { > > + ret = -ENOBUFS; > > + break; > > + } > > + reg = find_region(mem, addr, len); > > + if (!reg) { > > + ret = -EFAULT; > > + break; > > + } > > + _iov = iov + ret; > > + size = reg->memory_size - addr + reg->guest_phys_addr; > > + _iov->iov_len = min((u64)len, size); > > + _iov->iov_base = (void *) > > + (reg->userspace_addr + addr - reg->guest_phys_addr); > > + s += size; > > + addr += size; > > + ++ret; > > + } > > + > > + rcu_read_unlock(); > > + return ret; > > +} > > + > > +/* Each buffer in the virtqueues is actually a chain of descriptors. This > > + * function returns the next descriptor in the chain, or vq->vring.num if we're > > + * at the end. */ > > +static unsigned next_desc(struct vhost_virtqueue *vq, 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 vq->num; > > + > > + /* 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(); > > + > > + if (next >= vq->num) { > > + vq_err(vq, "Desc next is %u > %u", next, vq->num); > > + return vq->num; > > + } > > + > > + 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. */ > > +unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, > > + struct iovec iov[], > > + unsigned int *out_num, unsigned int *in_num) > > +{ > > + struct vring_desc desc; > > + unsigned int i, head; > > + u16 last_avail_idx; > > + int ret; > > + > > + /* Check it isn't doing very strange things with descriptor numbers. */ > > + last_avail_idx = vq->last_avail_idx; > > + if (get_user(vq->avail_idx, &vq->avail->idx)) { > > + vq_err(vq, "Failed to access avail idx at %p\n", > > + &vq->avail->idx); > > + return vq->num; > > + } > > + > > + if ((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 vq->num; > > + } > > + > > + /* If there's nothing new since last we looked, return invalid. */ > > + if (vq->avail_idx == last_avail_idx) > > + return vq->num; > > + > > + /* Grab the next descriptor number they're advertising, and increment > > + * the index we've seen. */ > > + if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) { > > + vq_err(vq, "Failed to read head: idx %d address %p\n", > > + last_avail_idx, > > + &vq->avail->ring[last_avail_idx % vq->num]); > > + return vq->num; > > + } > > + > > + /* If their number is silly, that's an error. */ > > + if (head >= vq->num) { > > + vq_err(vq, "Guest says index %u > %u is available", > > + head, vq->num); > > + return vq->num; > > + } > > + > > + vq->last_avail_idx++; > > + > > + /* When we start there are none of either input nor output. */ > > + *out_num = *in_num = 0; > > + > > + i = head; > > + do { > > + unsigned iov_count = *in_num + *out_num; > > + if (copy_from_user(&desc, vq->desc + i, sizeof desc)) { > > + vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", > > + i, vq->desc + i); > > + return vq->num; > > + } > > + ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, > > + VHOST_NET_MAX_SG - iov_count); > > + if (ret < 0) { > > + vq_err(vq, "Translation failure %d descriptor idx %d\n", > > + ret, i); > > + return vq->num; > > + } > > + /* If this is an input descriptor, increment that count. */ > > + if (desc.flags & VRING_DESC_F_WRITE) > > + *in_num += ret; > > + else { > > + /* If it's an output descriptor, they're all supposed > > + * to come before any input descriptors. */ > > + if (*in_num) { > > + vq_err(vq, "Descriptor has out after in: " > > + "idx %d\n", i); > > + return vq->num; > > + } > > + *out_num += ret; > > + } > > + } while ((i = next_desc(vq, &desc)) != vq->num); > > + return head; > > +} > > + > > +/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ > > +void vhost_discard_vq_desc(struct vhost_virtqueue *vq) > > +{ > > + vq->last_avail_idx--; > > +} > > + > > +/* After we've used one of their buffers, we tell them about it. We'll then > > + * want to send them an interrupt, using vq->call. */ > > +int vhost_add_used(struct vhost_virtqueue *vq, > > + unsigned int head, int len) > > +{ > > + struct vring_used_elem *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]; > > + if (put_user(head, &used->id)) { > > + vq_err(vq, "Failed to write used id"); > > + return -EFAULT; > > + } > > + if (put_user(len, &used->len)) { > > + vq_err(vq, "Failed to write used len"); > > + return -EFAULT; > > + } > > + /* Make sure buffer is written before we update index. */ > > + wmb(); > > + if (put_user(vq->last_used_idx + 1, &vq->used->idx)) { > > + vq_err(vq, "Failed to increment used idx"); > > + return -EFAULT; > > + } > > + vq->last_used_idx++; > > + return 0; > > +} > > + > > +/* This actually sends the interrupt for this virtqueue */ > > +void vhost_trigger_irq(struct vhost_dev *dev, struct vhost_virtqueue *vq) > > +{ > > + __u16 flags = 0; > > + if (get_user(flags, &vq->avail->flags)) { > > + vq_err(vq, "Failed to get flags"); > > + return; > > + } > > + > > + /* If they don't want an interrupt, don't send one, unless empty. */ > > + if ((flags & VRING_AVAIL_F_NO_INTERRUPT) && > > + (!vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) || > > + vq->avail_idx != vq->last_avail_idx)) > > + return; > > + > > + /* Send the Guest an interrupt tell them we used something up. */ > > + if (vq->call_ctx) > > + eventfd_signal(vq->call_ctx, 1); > > +} > > + > > +/* And here's the combo meal deal. Supersize me! */ > > +void vhost_add_used_and_trigger(struct vhost_dev *dev, > > + struct vhost_virtqueue *vq, > > + unsigned int head, int len) > > +{ > > + vhost_add_used(vq, head, len); > > + vhost_trigger_irq(dev, vq); > > +} > > + > > +/* OK, now we need to know about added descriptors. */ > > +bool vhost_notify(struct vhost_virtqueue *vq) > > +{ > > + int r; > > + if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) > > + return false; > > + vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; > > + r = put_user(vq->used_flags, &vq->used->flags); > > + if (r) > > + vq_err(vq, "Failed to disable notification: %d\n", r); > > + /* They could have slipped one in as we were doing that: make > > + * sure it's written, tell caller it needs to check again. */ > > + mb(); > > + return true; > > +} > > + > > +/* We don't need to be notified again. */ > > +void vhost_no_notify(struct vhost_virtqueue *vq) > > +{ > > + int r; > > + if (vq->used_flags & VRING_USED_F_NO_NOTIFY) > > + return; > > + vq->used_flags |= VRING_USED_F_NO_NOTIFY; > > + r = put_user(vq->used_flags, &vq->used->flags); > > + if (r) > > + vq_err(vq, "Failed to enable notification: %d\n", r); > > +} > > + > > +int vhost_init(void) > > +{ > > + vhost_workqueue = create_workqueue("vhost"); > > + if (!vhost_workqueue) > > + return -ENOMEM; > > + return 0; > > +} > > + > > +void vhost_cleanup(void) > > +{ > > + destroy_workqueue(vhost_workqueue); > > +} > > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > > new file mode 100644 > > index 0000000..8e13d06 > > --- /dev/null > > +++ b/drivers/vhost/vhost.h > > @@ -0,0 +1,122 @@ > > +#ifndef _VHOST_H > > +#define _VHOST_H > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +struct vhost_device; > > + > > +enum { > > + VHOST_NET_MAX_SG = MAX_SKB_FRAGS + 2, > > +}; > > + > > +/* Poll a file (eventfd or socket) */ > > +/* Note: there's nothing vhost specific about this structure. */ > > +struct vhost_poll { > > + poll_table table; > > + wait_queue_head_t *wqh; > > + wait_queue_t wait; > > + /* struct which will handle all actual work. */ > > + struct work_struct work; > > + unsigned long mask; > > +}; > > + > > +void vhost_poll_init(struct vhost_poll *poll, work_func_t func, > > + unsigned long mask); > > +void vhost_poll_start(struct vhost_poll *poll, struct file *file); > > +void vhost_poll_stop(struct vhost_poll *poll); > > +void vhost_poll_flush(struct vhost_poll *poll); > > + > > +/* The virtqueue structure describes a queue attached to a device. */ > > +struct vhost_virtqueue { > > + struct vhost_dev *dev; > > + > > + /* The actual ring of buffers. */ > > + struct mutex mutex; > > + unsigned int num; > > + struct vring_desc __user *desc; > > + struct vring_avail __user *avail; > > + struct vring_used __user *used; > > + struct file *kick; > > + struct file *call; > > + struct file *error; > > + struct eventfd_ctx *call_ctx; > > + struct eventfd_ctx *error_ctx; > > + > > + struct vhost_poll poll; > > + > > + /* The routine to call when the Guest pings us, or timeout. */ > > + work_func_t handle_kick; > > + > > + /* Last available index we saw. */ > > + u16 last_avail_idx; > > + > > + /* Caches available index value from user. */ > > + u16 avail_idx; > > + > > + /* Last index we used. */ > > + u16 last_used_idx; > > + > > + /* Used flags */ > > + u16 used_flags; > > + > > + struct iovec iov[VHOST_NET_MAX_SG]; > > + struct iovec hdr[VHOST_NET_MAX_SG]; > > +}; > > + > > +struct vhost_dev { > > + /* Readers use RCU to access memory table pointer. > > + * Writers use mutex below.*/ > > + struct vhost_memory *memory; > > + struct mm_struct *mm; > > + struct vhost_virtqueue *vqs; > > + int nvqs; > > + struct mutex mutex; > > + unsigned acked_features; > > +}; > > + > > +long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs); > > +long vhost_dev_check_owner(struct vhost_dev *); > > +long vhost_dev_reset_owner(struct vhost_dev *); > > +void vhost_dev_cleanup(struct vhost_dev *); > > +long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg); > > + > > +unsigned vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *, > > + struct iovec iov[], > > + unsigned int *out_num, unsigned int *in_num); > > +void vhost_discard_vq_desc(struct vhost_virtqueue *); > > + > > +int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len); > > +void vhost_trigger_irq(struct vhost_dev *, struct vhost_virtqueue *); > > +void vhost_add_used_and_trigger(struct vhost_dev *, struct vhost_virtqueue *, > > + unsigned int head, int len); > > +void vhost_no_notify(struct vhost_virtqueue *); > > +bool vhost_notify(struct vhost_virtqueue *); > > + > > +int vhost_init(void); > > +void vhost_cleanup(void); > > + > > +#define vq_err(vq, fmt, ...) do { \ > > + pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ > > + if ((vq)->error_ctx) \ > > + eventfd_signal((vq)->error_ctx, 1);\ > > + } while (0) > > + > > +enum { > > + VHOST_FEATURES = 1 << VIRTIO_F_NOTIFY_ON_EMPTY, > > +}; > > + > > +static inline int vhost_has_feature(struct vhost_dev *dev, int bit) > > +{ > > + return dev->acked_features & (1 << bit); > > +} > > + > > +#endif > > diff --git a/include/linux/Kbuild b/include/linux/Kbuild > > index dec2f18..975df9a 100644 > > --- a/include/linux/Kbuild > > +++ b/include/linux/Kbuild > > @@ -360,6 +360,7 @@ unifdef-y += uio.h > > unifdef-y += unistd.h > > unifdef-y += usbdevice_fs.h > > unifdef-y += utsname.h > > +unifdef-y += vhost.h > > unifdef-y += videodev2.h > > unifdef-y += videodev.h > > unifdef-y += virtio_config.h > > diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h > > index 0521177..781a8bb 100644 > > --- a/include/linux/miscdevice.h > > +++ b/include/linux/miscdevice.h > > @@ -30,6 +30,7 @@ > > #define HPET_MINOR 228 > > #define FUSE_MINOR 229 > > #define KVM_MINOR 232 > > +#define VHOST_NET_MINOR 233 > > #define MISC_DYNAMIC_MINOR 255 > > > > struct device; > > diff --git a/include/linux/vhost.h b/include/linux/vhost.h > > new file mode 100644 > > index 0000000..3f441a9 > > --- /dev/null > > +++ b/include/linux/vhost.h > > @@ -0,0 +1,101 @@ > > +#ifndef _LINUX_VHOST_H > > +#define _LINUX_VHOST_H > > +/* Userspace interface for in-kernel virtio accelerators. */ > > + > > +/* vhost is used to reduce the number of system calls involved in virtio. > > + * > > + * Existing virtio net code is used in the guest without modification. > > + * > > + * This header includes interface used by userspace hypervisor for > > + * device configuration. > > + */ > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +struct vhost_vring_state { > > + unsigned int index; > > + unsigned int num; > > +}; > > + > > +struct vhost_vring_file { > > + unsigned int index; > > + int fd; > > +}; > > + > > +struct vhost_vring_addr { > > + unsigned int index; > > + unsigned int padding; > > + __u64 user_addr; > > +}; > > + > > +struct vhost_memory_region { > > + __u64 guest_phys_addr; > > + __u64 memory_size; /* bytes */ > > + __u64 userspace_addr; > > + __u64 padding; /* read/write protection? */ > > +}; > > + > > +struct vhost_memory { > > + __u32 nregions; > > + __u32 padding; > > + struct vhost_memory_region regions[0]; > > +}; > > + > > +/* ioctls */ > > + > > +#define VHOST_VIRTIO 0xAF > > + > > +/* Features bitmask for forward compatibility. Transport bits are used for > > + * vhost specific features. */ > > +#define VHOST_GET_FEATURES _IOR(VHOST_VIRTIO, 0x00, __u64) > > +#define VHOST_ACK_FEATURES _IOW(VHOST_VIRTIO, 0x00, __u64) > > + > > +/* Set current process as the (exclusive) owner of this file descriptor. This > > + * must be called before any other vhost command. Further calls to > > + * VHOST_OWNER_SET fail until VHOST_OWNER_RESET is called. */ > > +#define VHOST_SET_OWNER _IO(VHOST_VIRTIO, 0x01) > > +/* Give up ownership, and reset the device to default values. > > + * Allows subsequent call to VHOST_OWNER_SET to succeed. */ > > +#define VHOST_RESET_OWNER _IO(VHOST_VIRTIO, 0x02) > > + > > +/* Set up/modify memory layout */ > > +#define VHOST_SET_MEM_TABLE _IOW(VHOST_VIRTIO, 0x03, struct vhost_memory) > > + > > +/* Ring setup. These parameters can not be modified while ring is running > > + * (bound to a device). */ > > +/* Set number of descriptors in ring */ > > +#define VHOST_SET_VRING_NUM _IOW(VHOST_VIRTIO, 0x10, struct vhost_vring_state) > > +/* Start of array of descriptors (virtually contiguous) */ > > +#define VHOST_SET_VRING_DESC _IOW(VHOST_VIRTIO, 0x11, struct vhost_vring_addr) > > +/* Used structure address */ > > +#define VHOST_SET_VRING_USED _IOW(VHOST_VIRTIO, 0x12, struct vhost_vring_addr) > > +/* Available structure address */ > > +#define VHOST_SET_VRING_AVAIL _IOW(VHOST_VIRTIO, 0x13, struct vhost_vring_addr) > > +/* Base value where queue looks for available descriptors */ > > +#define VHOST_SET_VRING_BASE _IOW(VHOST_VIRTIO, 0x14, struct vhost_vring_state) > > +/* Get accessor: reads index, writes value in num */ > > +#define VHOST_GET_VRING_BASE _IOWR(VHOST_VIRTIO, 0x14, struct vhost_vring_state) > > + > > +/* The following ioctls use eventfd file descriptors to signal and poll > > + * for events. */ > > + > > +/* Set eventfd to poll for added buffers */ > > +#define VHOST_SET_VRING_KICK _IOW(VHOST_VIRTIO, 0x20, struct vhost_vring_file) > > +/* Set eventfd to signal when buffers have beed used */ > > +#define VHOST_SET_VRING_CALL _IOW(VHOST_VIRTIO, 0x21, struct vhost_vring_file) > > +/* Set eventfd to signal an error */ > > +#define VHOST_SET_VRING_ERR _IOW(VHOST_VIRTIO, 0x22, struct vhost_vring_file) > > + > > +/* VHOST_NET specific defines */ > > + > > +/* Attach virtio net device to a raw socket. The socket must be already > > + * bound to an ethernet device, this device will be used for transmit. > > + * Pass -1 to unbind from the socket and the transmit device. > > + * This can be used to stop the device (e.g. for migration). */ > > +#define VHOST_NET_SET_SOCKET _IOW(VHOST_VIRTIO, 0x30, int) > > + > > +#endif > > -- > > 1.6.2.5 > > -- > > To unsubscribe from this list: send the line "unsubscribe netdev" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org