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Commit 5fc83528 authored by Linus Torvalds's avatar Linus Torvalds
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Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost 

Pull virtio/vhost cross endian support from Michael Tsirkin:
 "I have just queued some more bugfix patches today but none fix
  regressions and none are related to these ones, so it looks like a
  good time for a merge for -rc1.

  The motivation for this is support for legacy BE guests on the new LE
  hosts.  There are two redeeming properties that made me merge this:

   - It's a trivial amount of code: since we wrap host/guest accesses
     anyway, almost all of it is well hidden from drivers.

   - Sane platforms would never set flags like VHOST_CROSS_ENDIAN_LEGACY,
     and when it's clear, there's zero overhead (as some point it was
     tested by compiling with and without the patches, got the same
     stripped binary).

  Maybe we could create a Kconfig symbol to enforce the second point:
  prevent people from enabling it eg on x86.  I will look into this"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio-pci: alloc only resources actually used.
  macvtap/tun: cross-endian support for little-endian hosts
  vhost: cross-endian support for legacy devices
  virtio: add explicit big-endian support to memory accessors
  vhost: introduce vhost_is_little_endian() helper
  vringh: introduce vringh_is_little_endian() helper
  macvtap: introduce macvtap_is_little_endian() helper
  tun: add tun_is_little_endian() helper
  virtio: introduce virtio_is_little_endian() helper
parents 0cbee992 59a5b0f7

drivers/net/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -258,6 +258,20 @@ config TUN 


	  If you don't know what to use this for, you don't need it.



config TUN_VNET_CROSS_LE

	bool "Support for cross-endian vnet headers on little-endian kernels"

	default n

	---help---

	  This option allows TUN/TAP and MACVTAP device drivers in a

	  little-endian kernel to parse vnet headers that come from a

	  big-endian legacy virtio device.



	  Userspace programs can control the feature using the TUNSETVNETBE

	  and TUNGETVNETBE ioctls.



	  Unless you have a little-endian system hosting a big-endian virtual

	  machine with a legacy virtio NIC, you should say N.



config VETH

	tristate "Virtual ethernet pair device"

	---help---

drivers/net/macvtap.c

+63 −2
Original line number Diff line number Diff line
@@ -48,15 +48,70 @@ struct macvtap_queue { 
#define MACVTAP_FEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)



#define MACVTAP_VNET_LE 0x80000000

#define MACVTAP_VNET_BE 0x40000000



#ifdef CONFIG_TUN_VNET_CROSS_LE

static inline bool macvtap_legacy_is_little_endian(struct macvtap_queue *q)

{

	return q->flags & MACVTAP_VNET_BE ? false :

		virtio_legacy_is_little_endian();

}



static long macvtap_get_vnet_be(struct macvtap_queue *q, int __user *sp)

{

	int s = !!(q->flags & MACVTAP_VNET_BE);



	if (put_user(s, sp))

		return -EFAULT;



	return 0;

}



static long macvtap_set_vnet_be(struct macvtap_queue *q, int __user *sp)

{

	int s;



	if (get_user(s, sp))

		return -EFAULT;



	if (s)

		q->flags |= MACVTAP_VNET_BE;

	else

		q->flags &= ~MACVTAP_VNET_BE;



	return 0;

}

#else

static inline bool macvtap_legacy_is_little_endian(struct macvtap_queue *q)

{

	return virtio_legacy_is_little_endian();

}



static long macvtap_get_vnet_be(struct macvtap_queue *q, int __user *argp)

{

	return -EINVAL;

}



static long macvtap_set_vnet_be(struct macvtap_queue *q, int __user *argp)

{

	return -EINVAL;

}

#endif /* CONFIG_TUN_VNET_CROSS_LE */



static inline bool macvtap_is_little_endian(struct macvtap_queue *q)

{

	return q->flags & MACVTAP_VNET_LE ||

		macvtap_legacy_is_little_endian(q);

}



static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)

{

	return __virtio16_to_cpu(q->flags & MACVTAP_VNET_LE, val);

	return __virtio16_to_cpu(macvtap_is_little_endian(q), val);

}



static inline __virtio16 cpu_to_macvtap16(struct macvtap_queue *q, u16 val)

{

	return __cpu_to_virtio16(q->flags & MACVTAP_VNET_LE, val);

	return __cpu_to_virtio16(macvtap_is_little_endian(q), val);

}



static struct proto macvtap_proto = {
@@ -1085,6 +1140,12 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd, 
			q->flags &= ~MACVTAP_VNET_LE;

		return 0;



	case TUNGETVNETBE:

		return macvtap_get_vnet_be(q, sp);



	case TUNSETVNETBE:

		return macvtap_set_vnet_be(q, sp);



	case TUNSETOFFLOAD:

		/* let the user check for future flags */

		if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |

drivers/net/tun.c

+65 −2
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ do { \ 
#define TUN_FASYNC	IFF_ATTACH_QUEUE

/* High bits in flags field are unused. */

#define TUN_VNET_LE     0x80000000

#define TUN_VNET_BE     0x40000000



#define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \

		      IFF_MULTI_QUEUE)
@@ -205,14 +206,68 @@ struct tun_struct { 
	u32 flow_count;

};



#ifdef CONFIG_TUN_VNET_CROSS_LE

static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)

{

	return tun->flags & TUN_VNET_BE ? false :

		virtio_legacy_is_little_endian();

}



static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)

{

	int be = !!(tun->flags & TUN_VNET_BE);



	if (put_user(be, argp))

		return -EFAULT;



	return 0;

}



static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)

{

	int be;



	if (get_user(be, argp))

		return -EFAULT;



	if (be)

		tun->flags |= TUN_VNET_BE;

	else

		tun->flags &= ~TUN_VNET_BE;



	return 0;

}

#else

static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)

{

	return virtio_legacy_is_little_endian();

}



static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)

{

	return -EINVAL;

}



static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)

{

	return -EINVAL;

}

#endif /* CONFIG_TUN_VNET_CROSS_LE */



static inline bool tun_is_little_endian(struct tun_struct *tun)

{

	return tun->flags & TUN_VNET_LE ||

		tun_legacy_is_little_endian(tun);

}



static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)

{

	return __virtio16_to_cpu(tun->flags & TUN_VNET_LE, val);

	return __virtio16_to_cpu(tun_is_little_endian(tun), val);

}



static inline __virtio16 cpu_to_tun16(struct tun_struct *tun, u16 val)

{

	return __cpu_to_virtio16(tun->flags & TUN_VNET_LE, val);

	return __cpu_to_virtio16(tun_is_little_endian(tun), val);

}



static inline u32 tun_hashfn(u32 rxhash)
@@ -2044,6 +2099,14 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, 
			tun->flags &= ~TUN_VNET_LE;

		break;



	case TUNGETVNETBE:

		ret = tun_get_vnet_be(tun, argp);

		break;



	case TUNSETVNETBE:

		ret = tun_set_vnet_be(tun, argp);

		break;



	case TUNATTACHFILTER:

		/* Can be set only for TAPs */

		ret = -EINVAL;

drivers/vhost/Kconfig

+15 −0
Original line number Diff line number Diff line
@@ -32,3 +32,18 @@ config VHOST 
	---help---

	  This option is selected by any driver which needs to access

	  the core of vhost.



config VHOST_CROSS_ENDIAN_LEGACY

	bool "Cross-endian support for vhost"

	default n

	---help---

	  This option allows vhost to support guests with a different byte

	  ordering from host while using legacy virtio.



	  Userspace programs can control the feature using the

	  VHOST_SET_VRING_ENDIAN and VHOST_GET_VRING_ENDIAN ioctls.



	  This is only useful on a few platforms (ppc64 and arm64). Since it

	  adds some overhead, it is disabled by default.



	  If unsure, say "N".

drivers/vhost/vhost.c

+84 −1
Original line number Diff line number Diff line
@@ -36,6 +36,77 @@ enum { 
#define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])

#define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])



#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY

static void vhost_vq_reset_user_be(struct vhost_virtqueue *vq)

{

	vq->user_be = !virtio_legacy_is_little_endian();

}



static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)

{

	struct vhost_vring_state s;



	if (vq->private_data)

		return -EBUSY;



	if (copy_from_user(&s, argp, sizeof(s)))

		return -EFAULT;



	if (s.num != VHOST_VRING_LITTLE_ENDIAN &&

	    s.num != VHOST_VRING_BIG_ENDIAN)

		return -EINVAL;



	vq->user_be = s.num;



	return 0;

}



static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,

				   int __user *argp)

{

	struct vhost_vring_state s = {

		.index = idx,

		.num = vq->user_be

	};



	if (copy_to_user(argp, &s, sizeof(s)))

		return -EFAULT;



	return 0;

}



static void vhost_init_is_le(struct vhost_virtqueue *vq)

{

	/* Note for legacy virtio: user_be is initialized at reset time

	 * according to the host endianness. If userspace does not set an

	 * explicit endianness, the default behavior is native endian, as

	 * expected by legacy virtio.

	 */

	vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;

}

#else

static void vhost_vq_reset_user_be(struct vhost_virtqueue *vq)

{

}



static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)

{

	return -ENOIOCTLCMD;

}



static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,

				   int __user *argp)

{

	return -ENOIOCTLCMD;

}



static void vhost_init_is_le(struct vhost_virtqueue *vq)

{

	if (vhost_has_feature(vq, VIRTIO_F_VERSION_1))

		vq->is_le = true;

}

#endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */



static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,

			    poll_table *pt)

{
@@ -199,6 +270,8 @@ static void vhost_vq_reset(struct vhost_dev *dev, 
	vq->call = NULL;

	vq->log_ctx = NULL;

	vq->memory = NULL;

	vq->is_le = virtio_legacy_is_little_endian();

	vhost_vq_reset_user_be(vq);

}



static int vhost_worker(void *data)
@@ -806,6 +879,12 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) 
		} else

			filep = eventfp;

		break;

	case VHOST_SET_VRING_ENDIAN:

		r = vhost_set_vring_endian(vq, argp);

		break;

	case VHOST_GET_VRING_ENDIAN:

		r = vhost_get_vring_endian(vq, idx, argp);

		break;

	default:

		r = -ENOIOCTLCMD;

	}
@@ -1044,8 +1123,12 @@ int vhost_init_used(struct vhost_virtqueue *vq) 
{

	__virtio16 last_used_idx;

	int r;

	if (!vq->private_data)

	if (!vq->private_data) {

		vq->is_le = virtio_legacy_is_little_endian();

		return 0;

	}



	vhost_init_is_le(vq);



	r = vhost_update_used_flags(vq);

	if (r)