From cadb72854b44f53c07ea60d7a6149ccac5928a82 Mon Sep 17 00:00:00 2001

From: Claudio Imbrenda <cimbrend@redhat.com>

Date: Tue, 27 Oct 2020 12:02:15 -0400

Subject: [PATCH 02/18] libvhost-user: handle endianness as mandated by the

 spec

RH-Author: Claudio Imbrenda <cimbrend@redhat.com>

Message-id: <20201027120217.2997314-2-cimbrend@redhat.com>

Patchwork-id: 98723

O-Subject: [RHEL8.4 qemu-kvm PATCH 1/3] libvhost-user: handle endianness as mandated by the spec

Bugzilla: 1857733

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Thomas Huth <thuth@redhat.com>

RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

RH-Acked-by: Cornelia Huck <cohuck@redhat.com>

From: Marc Hartmayer <mhartmay@linux.ibm.com>

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>

(cherry picked from commit 2ffc54708087c6e524297957be2fc5d543abb767)

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 contrib/libvhost-user/libvhost-user.c | 77 +++++++++++++++------------

 1 file changed, 43 insertions(+), 34 deletions(-)

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c

index b89bf185013..b8350b067e3 100644

--- a/contrib/libvhost-user/libvhost-user.c

+++ b/contrib/libvhost-user/libvhost-user.c

@@ -42,6 +42,7 @@

 #include "qemu/atomic.h"

 #include "qemu/osdep.h"

+#include "qemu/bswap.h"

 #include "qemu/memfd.h"

 #include "libvhost-user.h"

@@ -522,6 +523,14 @@ 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);

@@ -886,7 +895,7 @@ 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 &&

@@ -998,7 +1007,7 @@ 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;

@@ -1737,13 +1746,13 @@ 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;

 }

@@ -1751,7 +1760,7 @@ 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

@@ -1839,12 +1848,12 @@ 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();

@@ -1887,8 +1896,8 @@ 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;

             }

@@ -1901,8 +1910,8 @@ 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);

@@ -1929,10 +1938,10 @@ 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;

@@ -2047,7 +2056,7 @@ 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

@@ -2057,7 +2066,7 @@ 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

@@ -2067,7 +2076,7 @@ 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

@@ -2156,14 +2165,14 @@ 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);

@@ -2185,10 +2194,10 @@ 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");

@@ -2196,7 +2205,7 @@ 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. */

@@ -2392,14 +2401,14 @@ 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);

@@ -2425,9 +2434,9 @@ 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;

         }

@@ -2452,15 +2461,15 @@ 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));

-- 

2.27.0