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libvhost-user: handle endianness as mandated by the spec

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Since virtio existed even before it got standardized, the virtio
standard defines the following types of virtio devices:

 + legacy device (pre-virtio 1.0)
 + non-legacy or VIRTIO 1.0 device
 + transitional device (which can act both as legacy and non-legacy)

Virtio 1.0 defines the fields of the virtqueues as little endian,
while legacy uses guest's native endian [1]. Currently libvhost-user
does not handle virtio endianness at all, i.e. it works only if the
native endianness matches with whatever is actually needed. That means
things break spectacularly on big-endian targets. Let us handle virtio
endianness for non-legacy as required by the virtio specification [1]
and fence legacy virtio, as there is no safe way to figure out the
needed endianness conversions for all cases. The fencing of legacy
virtio devices is done in `vu_set_features_exec`.

[1] https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html#x1-210003

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Message-id: 20200901150019.29229-3-mhartmay@linux.ibm.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Marc Hartmayer 2020-09-01 17:00:19 +02:00 committed by Stefan Hajnoczi
parent 1a94978983
commit 2ffc547080
1 changed files with 43 additions and 34 deletions
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77
contrib/libvhost-user/libvhost-user.c
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@ -42,6 +42,7 @@
#include "qemu/atomic.h"
#include "qemu/osdep.h"
#include "qemu/bswap.h"
#include "qemu/memfd.h"
#include "libvhost-user.h"
@ -539,6 +540,14 @@ vu_set_features_exec(VuDev *dev, VhostUserMsg *vmsg)
DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
dev->features = vmsg->payload.u64;
if (!vu_has_feature(dev, VIRTIO_F_VERSION_1)) {
/*
* We only support devices conforming to VIRTIO 1.0 or
* later
*/
vu_panic(dev, "virtio legacy devices aren't supported by libvhost-user");
return false;
}
if (!(dev->features & VHOST_USER_F_PROTOCOL_FEATURES)) {
vu_set_enable_all_rings(dev, true);
@ -1074,7 +1083,7 @@ vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *vmsg)
return false;
}
vq->used_idx = vq->vring.used->idx;
vq->used_idx = lduw_le_p(&vq->vring.used->idx);
if (vq->last_avail_idx != vq->used_idx) {
bool resume = dev->iface->queue_is_processed_in_order &&
@ -1191,7 +1200,7 @@ vu_check_queue_inflights(VuDev *dev, VuVirtq *vq)
return 0;
}
vq->used_idx = vq->vring.used->idx;
vq->used_idx = lduw_le_p(&vq->vring.used->idx);
vq->resubmit_num = 0;
vq->resubmit_list = NULL;
vq->counter = 0;
@ -2021,13 +2030,13 @@ vu_queue_started(const VuDev *dev, const VuVirtq *vq)
static inline uint16_t
vring_avail_flags(VuVirtq *vq)
{
return vq->vring.avail->flags;
return lduw_le_p(&vq->vring.avail->flags);
}
static inline uint16_t
vring_avail_idx(VuVirtq *vq)
{
vq->shadow_avail_idx = vq->vring.avail->idx;
vq->shadow_avail_idx = lduw_le_p(&vq->vring.avail->idx);
return vq->shadow_avail_idx;
}
@ -2035,7 +2044,7 @@ vring_avail_idx(VuVirtq *vq)
static inline uint16_t
vring_avail_ring(VuVirtq *vq, int i)
{
return vq->vring.avail->ring[i];
return lduw_le_p(&vq->vring.avail->ring[i]);
}
static inline uint16_t
@ -2123,12 +2132,12 @@ virtqueue_read_next_desc(VuDev *dev, struct vring_desc *desc,
int i, unsigned int max, unsigned int *next)
{
/* If this descriptor says it doesn't chain, we're done. */
if (!(desc[i].flags & VRING_DESC_F_NEXT)) {
if (!(lduw_le_p(&desc[i].flags) & VRING_DESC_F_NEXT)) {
return VIRTQUEUE_READ_DESC_DONE;
}
/* Check they're not leading us off end of descriptors. */
*next = desc[i].next;
*next = lduw_le_p(&desc[i].next);
/* Make sure compiler knows to grab that: we don't want it changing! */
smp_wmb();
@ -2171,8 +2180,8 @@ vu_queue_get_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int *in_bytes,
}
desc = vq->vring.desc;
if (desc[i].flags & VRING_DESC_F_INDIRECT) {
if (desc[i].len % sizeof(struct vring_desc)) {
if (lduw_le_p(&desc[i].flags) & VRING_DESC_F_INDIRECT) {
if (ldl_le_p(&desc[i].len) % sizeof(struct vring_desc)) {
vu_panic(dev, "Invalid size for indirect buffer table");
goto err;
}
@ -2185,8 +2194,8 @@ vu_queue_get_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int *in_bytes,
/* loop over the indirect descriptor table */
indirect = 1;
desc_addr = desc[i].addr;
desc_len = desc[i].len;
desc_addr = ldq_le_p(&desc[i].addr);
desc_len = ldl_le_p(&desc[i].len);
max = desc_len / sizeof(struct vring_desc);
read_len = desc_len;
desc = vu_gpa_to_va(dev, &read_len, desc_addr);
@ -2213,10 +2222,10 @@ vu_queue_get_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int *in_bytes,
goto err;
}
if (desc[i].flags & VRING_DESC_F_WRITE) {
in_total += desc[i].len;
if (lduw_le_p(&desc[i].flags) & VRING_DESC_F_WRITE) {
in_total += ldl_le_p(&desc[i].len);
} else {
out_total += desc[i].len;
out_total += ldl_le_p(&desc[i].len);
}
if (in_total >= max_in_bytes && out_total >= max_out_bytes) {
goto done;
@ -2367,7 +2376,7 @@ vring_used_flags_set_bit(VuVirtq *vq, int mask)
flags = (uint16_t *)((char*)vq->vring.used +
offsetof(struct vring_used, flags));
*flags |= mask;
stw_le_p(flags, lduw_le_p(flags) | mask);
}
static inline void
@ -2377,7 +2386,7 @@ vring_used_flags_unset_bit(VuVirtq *vq, int mask)
flags = (uint16_t *)((char*)vq->vring.used +
offsetof(struct vring_used, flags));
*flags &= ~mask;
stw_le_p(flags, lduw_le_p(flags) & ~mask);
}
static inline void
@ -2387,7 +2396,7 @@ vring_set_avail_event(VuVirtq *vq, uint16_t val)
return;
}
*((uint16_t *) &vq->vring.used->ring[vq->vring.num]) = val;
stw_le_p(&vq->vring.used->ring[vq->vring.num], val);
}
void
@ -2476,14 +2485,14 @@ vu_queue_map_desc(VuDev *dev, VuVirtq *vq, unsigned int idx, size_t sz)
struct vring_desc desc_buf[VIRTQUEUE_MAX_SIZE];
int rc;
if (desc[i].flags & VRING_DESC_F_INDIRECT) {
if (desc[i].len % sizeof(struct vring_desc)) {
if (lduw_le_p(&desc[i].flags) & VRING_DESC_F_INDIRECT) {
if (ldl_le_p(&desc[i].len) % sizeof(struct vring_desc)) {
vu_panic(dev, "Invalid size for indirect buffer table");
}
/* loop over the indirect descriptor table */
desc_addr = desc[i].addr;
desc_len = desc[i].len;
desc_addr = ldq_le_p(&desc[i].addr);
desc_len = ldl_le_p(&desc[i].len);
max = desc_len / sizeof(struct vring_desc);
read_len = desc_len;
desc = vu_gpa_to_va(dev, &read_len, desc_addr);
@ -2505,10 +2514,10 @@ vu_queue_map_desc(VuDev *dev, VuVirtq *vq, unsigned int idx, size_t sz)
/* Collect all the descriptors */
do {
if (desc[i].flags & VRING_DESC_F_WRITE) {
if (lduw_le_p(&desc[i].flags) & VRING_DESC_F_WRITE) {
virtqueue_map_desc(dev, &in_num, iov + out_num,
VIRTQUEUE_MAX_SIZE - out_num, true,
desc[i].addr, desc[i].len);
ldq_le_p(&desc[i].addr), ldl_le_p(&desc[i].len));
} else {
if (in_num) {
vu_panic(dev, "Incorrect order for descriptors");
@ -2516,7 +2525,7 @@ vu_queue_map_desc(VuDev *dev, VuVirtq *vq, unsigned int idx, size_t sz)
}
virtqueue_map_desc(dev, &out_num, iov,
VIRTQUEUE_MAX_SIZE, false,
desc[i].addr, desc[i].len);
ldq_le_p(&desc[i].addr), ldl_le_p(&desc[i].len));
}
/* If we've got too many, that implies a descriptor loop. */
@ -2712,14 +2721,14 @@ vu_log_queue_fill(VuDev *dev, VuVirtq *vq,
max = vq->vring.num;
i = elem->index;
if (desc[i].flags & VRING_DESC_F_INDIRECT) {
if (desc[i].len % sizeof(struct vring_desc)) {
if (lduw_le_p(&desc[i].flags) & VRING_DESC_F_INDIRECT) {
if (ldl_le_p(&desc[i].len) % sizeof(struct vring_desc)) {
vu_panic(dev, "Invalid size for indirect buffer table");
}
/* loop over the indirect descriptor table */
desc_addr = desc[i].addr;
desc_len = desc[i].len;
desc_addr = ldq_le_p(&desc[i].addr);
desc_len = ldl_le_p(&desc[i].len);
max = desc_len / sizeof(struct vring_desc);
read_len = desc_len;
desc = vu_gpa_to_va(dev, &read_len, desc_addr);
@ -2745,9 +2754,9 @@ vu_log_queue_fill(VuDev *dev, VuVirtq *vq,
return;
}
if (desc[i].flags & VRING_DESC_F_WRITE) {
min = MIN(desc[i].len, len);
vu_log_write(dev, desc[i].addr, min);
if (lduw_le_p(&desc[i].flags) & VRING_DESC_F_WRITE) {
min = MIN(ldl_le_p(&desc[i].len), len);
vu_log_write(dev, ldq_le_p(&desc[i].addr), min);
len -= min;
}
@ -2772,15 +2781,15 @@ vu_queue_fill(VuDev *dev, VuVirtq *vq,
idx = (idx + vq->used_idx) % vq->vring.num;
uelem.id = elem->index;
uelem.len = len;
stl_le_p(&uelem.id, elem->index);
stl_le_p(&uelem.len, len);
vring_used_write(dev, vq, &uelem, idx);
}
static inline
void vring_used_idx_set(VuDev *dev, VuVirtq *vq, uint16_t val)
{
vq->vring.used->idx = val;
stw_le_p(&vq->vring.used->idx, val);
vu_log_write(dev,
vq->vring.log_guest_addr + offsetof(struct vring_used, idx),
sizeof(vq->vring.used->idx));