diff options
Diffstat (limited to 'tools/lguest/lguest.c')
| -rw-r--r-- | tools/lguest/lguest.c | 32 |
1 files changed, 23 insertions, 9 deletions
diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c index 07a03452c227..68f67cf3d318 100644 --- a/tools/lguest/lguest.c +++ b/tools/lguest/lguest.c @@ -42,14 +42,6 @@ #include <pwd.h> #include <grp.h> -#include <linux/virtio_config.h> -#include <linux/virtio_net.h> -#include <linux/virtio_blk.h> -#include <linux/virtio_console.h> -#include <linux/virtio_rng.h> -#include <linux/virtio_ring.h> -#include <asm/bootparam.h> -#include "../../include/linux/lguest_launcher.h" /*L:110 * We can ignore the 43 include files we need for this program, but I do want * to draw attention to the use of kernel-style types. @@ -65,6 +57,15 @@ typedef uint16_t u16; typedef uint8_t u8; /*:*/ +#include <linux/virtio_config.h> +#include <linux/virtio_net.h> +#include <linux/virtio_blk.h> +#include <linux/virtio_console.h> +#include <linux/virtio_rng.h> +#include <linux/virtio_ring.h> +#include <asm/bootparam.h> +#include "../../include/linux/lguest_launcher.h" + #define BRIDGE_PFX "bridge:" #ifndef SIOCBRADDIF #define SIOCBRADDIF 0x89a2 /* add interface to bridge */ @@ -177,7 +178,8 @@ static struct termios orig_term; * in precise order. */ #define wmb() __asm__ __volatile__("" : : : "memory") -#define mb() __asm__ __volatile__("" : : : "memory") +#define rmb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory") +#define mb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory") /* Wrapper for the last available index. Makes it easier to change. */ #define lg_last_avail(vq) ((vq)->last_avail_idx) @@ -676,6 +678,12 @@ static unsigned wait_for_vq_desc(struct virtqueue *vq, errx(1, "Guest moved used index from %u to %u", last_avail, vq->vring.avail->idx); + /* + * Make sure we read the descriptor number *after* we read the ring + * update; don't let the cpu or compiler change the order. + */ + rmb(); + /* * Grab the next descriptor number they're advertising, and increment * the index we've seen. @@ -695,6 +703,12 @@ static unsigned wait_for_vq_desc(struct virtqueue *vq, i = head; /* + * We have to read the descriptor after we read the descriptor number, + * but there's a data dependency there so the CPU shouldn't reorder + * that: no rmb() required. + */ + + /* * If this is an indirect entry, then this buffer contains a descriptor * table which we handle as if it's any normal descriptor chain. */ |