[PATCH 0/2] Enable virtio-fs on s390x

[PATCH 0/2] Enable virtio-fs on s390x

[Marc Hartmayer]

This patch series is about enabling virtio-fs on s390x. For that we need
 + some shim code (first patch), and we need
 + libvhost-user to deal with virtio endiannes for non-legacy virtio
   devices as mandated by the spec.

How to use?

For general instructions how to use virtio-fs (on x86) please have a
look at https://virtio-fs.gitlab.io/howto-qemu.html. Most of the
instructions can also be applied on s390x.

In short:

1. Install self-compiled QEMU with this patch series applied
2. Prepare host and guest kernel so they support virtio-fs

Start virtiofsd on the host

 $ virtiofsd -f --socket-path=/tmp/vhostqemu -o source=/tmp/shared

Now you can start QEMU in a separate shell on the host:

 $ qemu-system-s390x -machine type=s390-ccw-virtio,accel=kvm,memory-backend=mem \
   -object memory-backend-file,id=mem,size=2G,mem-path=/dev/shm/virtiofs,share=on,prealloc=on,prealloc-threads=1 \
   -chardev socket,id=char0,path=/tmp/vhostqemu -device vhost-user-fs-ccw,queue-size=1024,chardev=char0,tag=myfs \
   -drive if=virtio,file=disk.qcow2 \
   -m 2G -smp 2 -nographic

Log into the guest and mount it

 $ mount -t virtiofs myfs /mnt

Changelog:
 RFC v2 -> v1:
 - patch 1:
  + Added `force_revision_1 = true` (Conny)
  + I didn't add the r-b from Stefan Hajnoczi as I've added the
    changes suggested by Conny
 - squashed patches 2 and 3:
  + removed assertion in performance critical code path (Stefan)
  + dropped all dead code (Stefan)
  + removed libvhost-access.h
  
 RFC v1 -> RFC v2:
  + rebased
  + drop patch "libvhost-user: print invalid address on vu_panic" as it's not related to this series
  + drop patch "[RFC 4/4] HACK: Hard-code the libvhost-user.o-cflags for s390x"
  + patch "virtio: add vhost-user-fs-ccw device": replace qdev_set_parent_bus and object_property_set_bool by qdev_realize
  + patch "libvhost-user: handle endianness as mandated by the spec":
    Drop support for legacy virtio devices
  + add patch to fence legacy virtio devices
*** BLURB HERE ***

Halil Pasic (1):
  virtio: add vhost-user-fs-ccw device

Marc Hartmayer (1):
  libvhost-user: handle endianness as mandated by the spec

 contrib/libvhost-user/libvhost-user.c | 77 +++++++++++++++------------
 hw/s390x/Makefile.objs                |  1 +
 hw/s390x/vhost-user-fs-ccw.c          | 75 ++++++++++++++++++++++++++
 3 files changed, 119 insertions(+), 34 deletions(-)
 create mode 100644 hw/s390x/vhost-user-fs-ccw.c

-- 
2.25.4

[PATCH 1/2] virtio: add vhost-user-fs-ccw device

[Marc Hartmayer]

From: Halil Pasic <pasic@linux.ibm.com>

Wire up the CCW device for vhost-user-fs.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
---
 hw/s390x/Makefile.objs       |  1 +
 hw/s390x/vhost-user-fs-ccw.c | 75 ++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 hw/s390x/vhost-user-fs-ccw.c

diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
index a46a1c7894e0..c4086ec3171e 100644
--- a/hw/s390x/Makefile.objs
+++ b/hw/s390x/Makefile.objs
@@ -20,6 +20,7 @@ obj-$(CONFIG_VIRTIO_NET) += virtio-ccw-net.o
 obj-$(CONFIG_VIRTIO_BLK) += virtio-ccw-blk.o
 obj-$(call land,$(CONFIG_VIRTIO_9P),$(CONFIG_VIRTFS)) += virtio-ccw-9p.o
 obj-$(CONFIG_VHOST_VSOCK) += vhost-vsock-ccw.o
+obj-$(CONFIG_VHOST_USER_FS) += vhost-user-fs-ccw.o
 endif
 obj-y += css-bridge.o
 obj-y += ccw-device.o
diff --git a/hw/s390x/vhost-user-fs-ccw.c b/hw/s390x/vhost-user-fs-ccw.c
new file mode 100644
index 000000000000..6c6f26929301
--- /dev/null
+++ b/hw/s390x/vhost-user-fs-ccw.c
@@ -0,0 +1,75 @@
+/*
+ * virtio ccw vhost-user-fs implementation
+ *
+ * Copyright 2020 IBM Corp.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+#include "qemu/osdep.h"
+#include "hw/qdev-properties.h"
+#include "qapi/error.h"
+#include "hw/virtio/vhost-user-fs.h"
+#include "virtio-ccw.h"
+
+typedef struct VHostUserFSCcw {
+    VirtioCcwDevice parent_obj;
+    VHostUserFS vdev;
+} VHostUserFSCcw;
+
+#define TYPE_VHOST_USER_FS_CCW "vhost-user-fs-ccw"
+#define VHOST_USER_FS_CCW(obj) \
+        OBJECT_CHECK(VHostUserFSCcw, (obj), TYPE_VHOST_USER_FS_CCW)
+
+
+static Property vhost_user_fs_ccw_properties[] = {
+    DEFINE_PROP_BIT("ioeventfd", VirtioCcwDevice, flags,
+                    VIRTIO_CCW_FLAG_USE_IOEVENTFD_BIT, true),
+    DEFINE_PROP_UINT32("max_revision", VirtioCcwDevice, max_rev,
+                       VIRTIO_CCW_MAX_REV),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void vhost_user_fs_ccw_realize(VirtioCcwDevice *ccw_dev, Error **errp)
+{
+    VHostUserFSCcw *dev = VHOST_USER_FS_CCW(ccw_dev);
+    DeviceState *vdev = DEVICE(&dev->vdev);
+
+    qdev_realize(vdev, BUS(&ccw_dev->bus), errp);
+}
+
+static void vhost_user_fs_ccw_instance_init(Object *obj)
+{
+    VHostUserFSCcw *dev = VHOST_USER_FS_CCW(obj);
+    VirtioCcwDevice *ccw_dev = VIRTIO_CCW_DEVICE(obj);
+
+    ccw_dev->force_revision_1 = true;
+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
+                                TYPE_VHOST_USER_FS);
+}
+
+static void vhost_user_fs_ccw_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtIOCCWDeviceClass *k = VIRTIO_CCW_DEVICE_CLASS(klass);
+
+    k->realize = vhost_user_fs_ccw_realize;
+    device_class_set_props(dc, vhost_user_fs_ccw_properties);
+    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
+}
+
+static const TypeInfo vhost_user_fs_ccw = {
+    .name          = TYPE_VHOST_USER_FS_CCW,
+    .parent        = TYPE_VIRTIO_CCW_DEVICE,
+    .instance_size = sizeof(VHostUserFSCcw),
+    .instance_init = vhost_user_fs_ccw_instance_init,
+    .class_init    = vhost_user_fs_ccw_class_init,
+};
+
+static void vhost_user_fs_ccw_register(void)
+{
+    type_register_static(&vhost_user_fs_ccw);
+}
+
+type_init(vhost_user_fs_ccw_register)
-- 
2.25.4

[PATCH 2/2] libvhost-user: handle endianness as mandated by the spec

[Marc Hartmayer]

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]. 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

Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.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 53f16bdf082c..e2238a0400c9 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"
@@ -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));
-- 
2.25.4

Re: [PATCH 1/2] virtio: add vhost-user-fs-ccw device

[Cornelia Huck]

On Thu, 30 Jul 2020 16:07:30 +0200
Marc Hartmayer <mhartmay@linux.ibm.com> wrote:

> From: Halil Pasic <pasic@linux.ibm.com>
> 
> Wire up the CCW device for vhost-user-fs.
> 
> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
> ---
>  hw/s390x/Makefile.objs       |  1 +
>  hw/s390x/vhost-user-fs-ccw.c | 75 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 76 insertions(+)
>  create mode 100644 hw/s390x/vhost-user-fs-ccw.c

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

Re: [PATCH 2/2] libvhost-user: handle endianness as mandated by the spec

[Michael S. Tsirkin]

On Thu, Jul 30, 2020 at 04:07:31PM +0200, Marc Hartmayer wrote:
> 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]. 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
> 
> Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>


Reviewed-by: Michael S. Tsirkin <mst@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 53f16bdf082c..e2238a0400c9 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"
> @@ -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));
> -- 
> 2.25.4

Re: [PATCH 0/2] Enable virtio-fs on s390x

[Michael S. Tsirkin]

On Thu, Jul 30, 2020 at 04:07:29PM +0200, Marc Hartmayer wrote:
> This patch series is about enabling virtio-fs on s390x. For that we need
>  + some shim code (first patch), and we need
>  + libvhost-user to deal with virtio endiannes for non-legacy virtio
>    devices as mandated by the spec.
> 
> How to use?
> 
> For general instructions how to use virtio-fs (on x86) please have a
> look at https://virtio-fs.gitlab.io/howto-qemu.html. Most of the
> instructions can also be applied on s390x.
> 
> In short:
> 
> 1. Install self-compiled QEMU with this patch series applied
> 2. Prepare host and guest kernel so they support virtio-fs
> 
> Start virtiofsd on the host
> 
>  $ virtiofsd -f --socket-path=/tmp/vhostqemu -o source=/tmp/shared
> 
> Now you can start QEMU in a separate shell on the host:
> 
>  $ qemu-system-s390x -machine type=s390-ccw-virtio,accel=kvm,memory-backend=mem \
>    -object memory-backend-file,id=mem,size=2G,mem-path=/dev/shm/virtiofs,share=on,prealloc=on,prealloc-threads=1 \
>    -chardev socket,id=char0,path=/tmp/vhostqemu -device vhost-user-fs-ccw,queue-size=1024,chardev=char0,tag=myfs \
>    -drive if=virtio,file=disk.qcow2 \
>    -m 2G -smp 2 -nographic
> 
> Log into the guest and mount it
> 
>  $ mount -t virtiofs myfs /mnt

Who's merging this? My tree?

> Changelog:
>  RFC v2 -> v1:
>  - patch 1:
>   + Added `force_revision_1 = true` (Conny)
>   + I didn't add the r-b from Stefan Hajnoczi as I've added the
>     changes suggested by Conny
>  - squashed patches 2 and 3:
>   + removed assertion in performance critical code path (Stefan)
>   + dropped all dead code (Stefan)
>   + removed libvhost-access.h
>   
>  RFC v1 -> RFC v2:
>   + rebased
>   + drop patch "libvhost-user: print invalid address on vu_panic" as it's not related to this series
>   + drop patch "[RFC 4/4] HACK: Hard-code the libvhost-user.o-cflags for s390x"
>   + patch "virtio: add vhost-user-fs-ccw device": replace qdev_set_parent_bus and object_property_set_bool by qdev_realize
>   + patch "libvhost-user: handle endianness as mandated by the spec":
>     Drop support for legacy virtio devices
>   + add patch to fence legacy virtio devices
> *** BLURB HERE ***
> 
> Halil Pasic (1):
>   virtio: add vhost-user-fs-ccw device
> 
> Marc Hartmayer (1):
>   libvhost-user: handle endianness as mandated by the spec
> 
>  contrib/libvhost-user/libvhost-user.c | 77 +++++++++++++++------------
>  hw/s390x/Makefile.objs                |  1 +
>  hw/s390x/vhost-user-fs-ccw.c          | 75 ++++++++++++++++++++++++++
>  3 files changed, 119 insertions(+), 34 deletions(-)
>  create mode 100644 hw/s390x/vhost-user-fs-ccw.c
> 
> -- 
> 2.25.4

Re: [PATCH 2/2] libvhost-user: handle endianness as mandated by the spec

[Cornelia Huck]

On Thu, 30 Jul 2020 16:07:31 +0200
Marc Hartmayer <mhartmay@linux.ibm.com> wrote:

> 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]. 

Maybe add

"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`.

Not that I disagree with fencing legacy virtio, but looking at some
vhost-user* drivers, I'm not sure everything will work as desired for
those (I might be missing something, though.)

- vhost-user-blk lists VERSION_1 in the supported features, but
  vhost-user-scsi doesn't... is there some inheritance going on that
  I'm missing?
- vhost-user-gpu-pci inherits from virtio-gpu-pci, so I guess it's fine
- vhost-user-input should also always have been virtio-1

So, has anybody been using vhost-user-scsi and can confirm that it
still works, or at least can be made to work?

> 
> [1] https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html#x1-210003
> 
> Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
> ---
>  contrib/libvhost-user/libvhost-user.c | 77 +++++++++++++++------------
>  1 file changed, 43 insertions(+), 34 deletions(-)

The code change per se LGTM.

Re: [PATCH 2/2] libvhost-user: handle endianness as mandated by the spec

[Marc Hartmayer]

On Sun, Aug 02, 2020 at 01:13 AM -0400, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Thu, Jul 30, 2020 at 04:07:31PM +0200, Marc Hartmayer wrote:
>> 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]. 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
>> 
>> Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>
>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Thanks.

[…snip]

-- 
Kind regards / Beste Grüße
   Marc Hartmayer

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Gregor Pillen 
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294

Re: [PATCH 0/2] Enable virtio-fs on s390x

[Dr. David Alan Gilbert]

* Michael S. Tsirkin (mst@redhat.com) wrote:
> On Thu, Jul 30, 2020 at 04:07:29PM +0200, Marc Hartmayer wrote:
> > This patch series is about enabling virtio-fs on s390x. For that we need
> >  + some shim code (first patch), and we need
> >  + libvhost-user to deal with virtio endiannes for non-legacy virtio
> >    devices as mandated by the spec.
> > 
> > How to use?
> > 
> > For general instructions how to use virtio-fs (on x86) please have a
> > look at https://virtio-fs.gitlab.io/howto-qemu.html. Most of the
> > instructions can also be applied on s390x.
> > 
> > In short:
> > 
> > 1. Install self-compiled QEMU with this patch series applied
> > 2. Prepare host and guest kernel so they support virtio-fs
> > 
> > Start virtiofsd on the host
> > 
> >  $ virtiofsd -f --socket-path=/tmp/vhostqemu -o source=/tmp/shared
> > 
> > Now you can start QEMU in a separate shell on the host:
> > 
> >  $ qemu-system-s390x -machine type=s390-ccw-virtio,accel=kvm,memory-backend=mem \
> >    -object memory-backend-file,id=mem,size=2G,mem-path=/dev/shm/virtiofs,share=on,prealloc=on,prealloc-threads=1 \
> >    -chardev socket,id=char0,path=/tmp/vhostqemu -device vhost-user-fs-ccw,queue-size=1024,chardev=char0,tag=myfs \
> >    -drive if=virtio,file=disk.qcow2 \
> >    -m 2G -smp 2 -nographic
> > 
> > Log into the guest and mount it
> > 
> >  $ mount -t virtiofs myfs /mnt
> 
> Who's merging this? My tree?

I think so; it seems either generic virtio or s390 more than actually
virtiofs specific in most of it.

Dave

> > Changelog:
> >  RFC v2 -> v1:
> >  - patch 1:
> >   + Added `force_revision_1 = true` (Conny)
> >   + I didn't add the r-b from Stefan Hajnoczi as I've added the
> >     changes suggested by Conny
> >  - squashed patches 2 and 3:
> >   + removed assertion in performance critical code path (Stefan)
> >   + dropped all dead code (Stefan)
> >   + removed libvhost-access.h
> >   
> >  RFC v1 -> RFC v2:
> >   + rebased
> >   + drop patch "libvhost-user: print invalid address on vu_panic" as it's not related to this series
> >   + drop patch "[RFC 4/4] HACK: Hard-code the libvhost-user.o-cflags for s390x"
> >   + patch "virtio: add vhost-user-fs-ccw device": replace qdev_set_parent_bus and object_property_set_bool by qdev_realize
> >   + patch "libvhost-user: handle endianness as mandated by the spec":
> >     Drop support for legacy virtio devices
> >   + add patch to fence legacy virtio devices
> > *** BLURB HERE ***
> > 
> > Halil Pasic (1):
> >   virtio: add vhost-user-fs-ccw device
> > 
> > Marc Hartmayer (1):
> >   libvhost-user: handle endianness as mandated by the spec
> > 
> >  contrib/libvhost-user/libvhost-user.c | 77 +++++++++++++++------------
> >  hw/s390x/Makefile.objs                |  1 +
> >  hw/s390x/vhost-user-fs-ccw.c          | 75 ++++++++++++++++++++++++++
> >  3 files changed, 119 insertions(+), 34 deletions(-)
> >  create mode 100644 hw/s390x/vhost-user-fs-ccw.c
> > 
> > -- 
> > 2.25.4
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [PATCH 2/2] libvhost-user: handle endianness as mandated by the spec

[Marc Hartmayer]

On Mon, Aug 03, 2020 at 11:26 AM +0200, Cornelia Huck <cohuck@redhat.com> wrote:
> On Thu, 30 Jul 2020 16:07:31 +0200
> Marc Hartmayer <mhartmay@linux.ibm.com> wrote:
>
>> 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]. 
>
> Maybe add
>
> "and fence legacy virtio, as there is no safe way to figure out the
> needed endianness conversions for all cases."

Okay.

>
>> The fencing of legacy virtio devices is done in
>> `vu_set_features_exec`.
>
> Not that I disagree with fencing legacy virtio, but looking at some
> vhost-user* drivers, I'm not sure everything will work as desired for
> those (I might be missing something, though.)
>
> - vhost-user-blk lists VERSION_1 in the supported features, but
>   vhost-user-scsi doesn't... is there some inheritance going on that
>   I'm missing?
> - vhost-user-gpu-pci inherits from virtio-gpu-pci, so I guess it's fine
> - vhost-user-input should also always have been virtio-1
>
> So, has anybody been using vhost-user-scsi and can confirm that it
> still works, or at least can be made to work?

Unfortunately, I don’t have the required hardware :/ Can please anybody
verify this?

>
>> 
>> [1] https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html#x1-210003
>> 
>> Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>> ---
>>  contrib/libvhost-user/libvhost-user.c | 77 +++++++++++++++------------
>>  1 file changed, 43 insertions(+), 34 deletions(-)
>
> The code change per se LGTM.

Thanks for the feedback!

>
-- 
Kind regards / Beste Grüße
   Marc Hartmayer

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Gregor Pillen 
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294

Re: [PATCH 0/2] Enable virtio-fs on s390x

[Michael S. Tsirkin]

On Thu, Jul 30, 2020 at 04:07:29PM +0200, Marc Hartmayer wrote:
> This patch series is about enabling virtio-fs on s390x. For that we need
>  + some shim code (first patch), and we need
>  + libvhost-user to deal with virtio endiannes for non-legacy virtio
>    devices as mandated by the spec.


Please rebase, address Cornelia's minor comments and repost.
Thanks!

> How to use?
> 
> For general instructions how to use virtio-fs (on x86) please have a
> look at https://virtio-fs.gitlab.io/howto-qemu.html. Most of the
> instructions can also be applied on s390x.
> 
> In short:
> 
> 1. Install self-compiled QEMU with this patch series applied
> 2. Prepare host and guest kernel so they support virtio-fs
> 
> Start virtiofsd on the host
> 
>  $ virtiofsd -f --socket-path=/tmp/vhostqemu -o source=/tmp/shared
> 
> Now you can start QEMU in a separate shell on the host:
> 
>  $ qemu-system-s390x -machine type=s390-ccw-virtio,accel=kvm,memory-backend=mem \
>    -object memory-backend-file,id=mem,size=2G,mem-path=/dev/shm/virtiofs,share=on,prealloc=on,prealloc-threads=1 \
>    -chardev socket,id=char0,path=/tmp/vhostqemu -device vhost-user-fs-ccw,queue-size=1024,chardev=char0,tag=myfs \
>    -drive if=virtio,file=disk.qcow2 \
>    -m 2G -smp 2 -nographic
> 
> Log into the guest and mount it
> 
>  $ mount -t virtiofs myfs /mnt
> 
> Changelog:
>  RFC v2 -> v1:
>  - patch 1:
>   + Added `force_revision_1 = true` (Conny)
>   + I didn't add the r-b from Stefan Hajnoczi as I've added the
>     changes suggested by Conny
>  - squashed patches 2 and 3:
>   + removed assertion in performance critical code path (Stefan)
>   + dropped all dead code (Stefan)
>   + removed libvhost-access.h
>   
>  RFC v1 -> RFC v2:
>   + rebased
>   + drop patch "libvhost-user: print invalid address on vu_panic" as it's not related to this series
>   + drop patch "[RFC 4/4] HACK: Hard-code the libvhost-user.o-cflags for s390x"
>   + patch "virtio: add vhost-user-fs-ccw device": replace qdev_set_parent_bus and object_property_set_bool by qdev_realize
>   + patch "libvhost-user: handle endianness as mandated by the spec":
>     Drop support for legacy virtio devices
>   + add patch to fence legacy virtio devices
> *** BLURB HERE ***
> 
> Halil Pasic (1):
>   virtio: add vhost-user-fs-ccw device
> 
> Marc Hartmayer (1):
>   libvhost-user: handle endianness as mandated by the spec
> 
>  contrib/libvhost-user/libvhost-user.c | 77 +++++++++++++++------------
>  hw/s390x/Makefile.objs                |  1 +
>  hw/s390x/vhost-user-fs-ccw.c          | 75 ++++++++++++++++++++++++++
>  3 files changed, 119 insertions(+), 34 deletions(-)
>  create mode 100644 hw/s390x/vhost-user-fs-ccw.c
> 
> -- 
> 2.25.4

Re: [PATCH 0/2] Enable virtio-fs on s390x

[Cornelia Huck]

On Thu, 27 Aug 2020 08:19:44 -0400
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Thu, Jul 30, 2020 at 04:07:29PM +0200, Marc Hartmayer wrote:
> > This patch series is about enabling virtio-fs on s390x. For that we need
> >  + some shim code (first patch), and we need
> >  + libvhost-user to deal with virtio endiannes for non-legacy virtio
> >    devices as mandated by the spec.  
> 
> 
> Please rebase, address Cornelia's minor comments and repost.

I think we're still waiting for someone to confirm the status of
vhost-user-scsi?