It turns out the lguest (and possibly kvm) want the addresses in the
ring buffer to only cover a certain part of memory, and be offset.
It makes sense that this be an ioctl.
Signed-off-by: Rusty Russell <[EMAIL PROTECTED]>
diff -r 08fb00b8acab Documentation/ioctl-number.txt
--- a/Documentation/ioctl-number.txt Sat Apr 05 21:31:40 2008 +1100
+++ b/Documentation/ioctl-number.txt Sat Apr 05 22:00:10 2008 +1100
@@ -183,6 +183,7 @@ 0xAC 00-1F linux/raw.h
0xAC 00-1F linux/raw.h
0xAD 00 Netfilter device in development:
<mailto:[EMAIL PROTECTED]>
+0xAE 00-01 linux/vring.h
0xB0 all RATIO devices in development:
<mailto:[EMAIL PROTECTED]>
0xB1 00-1F PPPoX <mailto:[EMAIL PROTECTED]>
diff -r 08fb00b8acab fs/vring.c
--- a/fs/vring.c Sat Apr 05 21:31:40 2008 +1100
+++ b/fs/vring.c Sat Apr 05 22:00:10 2008 +1100
@@ -38,6 +38,8 @@ struct vring_info
u16 mask;
u16 __user *last_used;
u16 last_avail;
+
+ unsigned long base, limit;
const struct vring_ops *ops;
void *ops_data;
@@ -120,10 +122,30 @@ static int vring_release(struct inode *i
return 0;
}
+static int vring_ioctl(struct inode *in, struct file *filp,
+ unsigned int cmd, unsigned long arg)
+{
+ struct vring_info *vr = filp->private_data;
+
+ switch (cmd) {
+ case VRINGSETBASE:
+ vr->base = arg;
+ break;
+ case VRINGSETLIMIT:
+ vr->limit = arg;
+ break;
+ default:
+ return -ENOTTY;
+ }
+
+ return 0;
+}
+
static const struct file_operations vring_fops = {
.release = vring_release,
.write = vring_write,
.poll = vring_poll,
+ .ioctl = vring_ioctl,
};
asmlinkage long sys_vringfd(void __user *addr,
@@ -166,6 +188,8 @@ asmlinkage long sys_vringfd(void __user
vr->mask = num_descs - 1;
vr->ops = NULL;
vr->used = NULL;
+ vr->limit = -1UL;
+ vr->base = 0;
err = get_user(vr->last_avail, &vr->ring.avail->idx);
if (err)
@@ -208,12 +232,15 @@ int vring_get_buffer(struct vring_info *
out_len = &dummy;
*in_len = *out_len = 0;
-
- if (unlikely(get_user(head, &vr->ring.avail->ring[head]) != 0))
+
+ if (unlikely(get_user(head, &vr->ring.avail->ring[vr->last_avail
+ % vr->ring.num])))
return -EFAULT;
i = head;
do {
+ void __user *base;
+
if (unlikely(i >= vr->ring.num)) {
pr_debug("vring: bad index: %u\n", i);
return -EINVAL;
@@ -222,24 +249,38 @@ int vring_get_buffer(struct vring_info *
if (copy_from_user(&d, &vr->ring.desc[i], sizeof(d)) != 0)
return -EFAULT;
+ if (d.addr + d.len > vr->limit || (d.addr + d.len < d.addr)) {
+ pr_debug("vring: bad addr/len: [EMAIL PROTECTED]",
+ d.len, (void *)(unsigned long)d.addr);
+ return -EINVAL;
+ }
+
+ base = (void __user *)(unsigned long)d.addr + vr->base;
+
if (d.flags & VRING_DESC_F_WRITE) {
/* Check for length and iovec overflows */
- if (!num_in)
+ if (!num_in) {
+ pr_debug("vring: writable desc %u in ring %p\n",
+ i, vr->ring.desc);
return -EINVAL;
+ }
if (in == *num_in || *in_len + d.len < *in_len)
return -E2BIG;
in_iov[in].iov_len = d.len;
*in_len += d.len;
- in_iov[in].iov_base = (void __user*)(long)d.addr;
+ in_iov[in].iov_base = base;
in++;
} else {
- if (!num_out)
+ if (!num_out) {
+ pr_debug("vring: readable desc %u in ring %p\n",
+ i, vr->ring.desc);
return -EINVAL;
+ }
if (out == *num_out || *out_len + d.len < *out_len)
return -E2BIG;
out_iov[out].iov_len = d.len;
*out_len += d.len;
- out_iov[out].iov_base = (void __user*)(long)d.addr;
+ out_iov[out].iov_base = base;
out++;
}
diff -r 08fb00b8acab include/linux/vring.h
--- a/include/linux/vring.h Sat Apr 05 21:31:40 2008 +1100
+++ b/include/linux/vring.h Sat Apr 05 22:00:10 2008 +1100
@@ -18,7 +18,13 @@
*/
#ifndef _LINUX_VRING_H
#define _LINUX_VRING_H
+#include <linux/types.h>
+/* Ioctl defines, as in "ioctls are AEgly". */
+#define VRINGSETBASE _IO(0xAE, 0)
+#define VRINGSETLIMIT _IO(0xAE, 1)
+
+#ifdef __KERNEL__
/* All members are optional */
struct vring_ops
{
@@ -51,4 +57,6 @@ void vring_used_buffer_atomic(struct vri
void vring_used_buffer_atomic(struct vring_info *vr, int id, u32 len);
void vring_wake(struct vring_info *vr);
+#endif /* __KERNEL__ */
+
#endif /* _LINUX_VRING_H */
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