Hi
On Thu, May 21, 2020 at 7:00 AM Raphael Norwitz <raphael.norw...@nutanix.com>
wrote:
> This change introduces a new feature to the vhost-user protocol allowing
> a backend device to specify the maximum number of ram slots it supports.
>
> At this point, the value returned by the backend will be capped at the
> maximum number of ram slots which can be supported by vhost-user, which
> is currently set to 8 because of underlying protocol limitations.
>
> The returned value will be stored inside the VhostUserState struct so
> that on device reconnect we can verify that the ram slot limitation
> has not decreased since the last time the device connected.
>
> Signed-off-by: Raphael Norwitz <raphael.norw...@nutanix.com>
> Signed-off-by: Peter Turschmid <peter.turs...@nutanix.com>
>
Reviewed-by: Marc-André Lureau <marcandre.lur...@redhat.com>
---
> docs/interop/vhost-user.rst | 16 ++++++++++++++
> hw/virtio/vhost-user.c | 49
> ++++++++++++++++++++++++++++++++++++++++--
> include/hw/virtio/vhost-user.h | 1 +
> 3 files changed, 64 insertions(+), 2 deletions(-)
>
> diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
> index 3b1b660..b3cf5c3 100644
> --- a/docs/interop/vhost-user.rst
> +++ b/docs/interop/vhost-user.rst
> @@ -815,6 +815,7 @@ Protocol features
> #define VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD 12
> #define VHOST_USER_PROTOCOL_F_RESET_DEVICE 13
> #define VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS 14
> + #define VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS 15
>
> Master message types
> --------------------
> @@ -1263,6 +1264,21 @@ Master message types
>
> The state.num field is currently reserved and must be set to 0.
>
> +``VHOST_USER_GET_MAX_MEM_SLOTS``
> + :id: 36
> + :equivalent ioctl: N/A
> + :slave payload: u64
> +
> + When the ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol
> + feature has been successfully negotiated, this message is submitted
> + by master to the slave. The slave should return the message with a
> + u64 payload containing the maximum number of memory slots for
> + QEMU to expose to the guest. At this point, the value returned
> + by the backend will be capped at the maximum number of ram slots
> + which can be supported by vhost-user. Currently that limit is set
> + at VHOST_USER_MAX_RAM_SLOTS = 8 because of underlying protocol
> + limitations.
> +
> Slave message types
> -------------------
>
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 442b0d6..0af593f 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -59,6 +59,8 @@ enum VhostUserProtocolFeature {
> VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11,
> VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12,
> VHOST_USER_PROTOCOL_F_RESET_DEVICE = 13,
> + /* Feature 14 reserved for
> VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS. */
> + VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,
> VHOST_USER_PROTOCOL_F_MAX
> };
>
> @@ -100,6 +102,8 @@ typedef enum VhostUserRequest {
> VHOST_USER_SET_INFLIGHT_FD = 32,
> VHOST_USER_GPU_SET_SOCKET = 33,
> VHOST_USER_RESET_DEVICE = 34,
> + /* Message number 35 reserved for VHOST_USER_VRING_KICK. */
> + VHOST_USER_GET_MAX_MEM_SLOTS = 36,
> VHOST_USER_MAX
> } VhostUserRequest;
>
> @@ -895,6 +899,23 @@ static int vhost_user_set_owner(struct vhost_dev *dev)
> return 0;
> }
>
> +static int vhost_user_get_max_memslots(struct vhost_dev *dev,
> + uint64_t *max_memslots)
> +{
> + uint64_t backend_max_memslots;
> + int err;
> +
> + err = vhost_user_get_u64(dev, VHOST_USER_GET_MAX_MEM_SLOTS,
> + &backend_max_memslots);
> + if (err < 0) {
> + return err;
> + }
> +
> + *max_memslots = backend_max_memslots;
> +
> + return 0;
> +}
> +
> static int vhost_user_reset_device(struct vhost_dev *dev)
> {
> VhostUserMsg msg = {
> @@ -1392,7 +1413,7 @@ static int
> vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
>
> static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque)
> {
> - uint64_t features, protocol_features;
> + uint64_t features, protocol_features, ram_slots;
> struct vhost_user *u;
> int err;
>
> @@ -1454,6 +1475,27 @@ static int vhost_user_backend_init(struct vhost_dev
> *dev, void *opaque)
> "slave-req protocol features.");
> return -1;
> }
> +
> + /* get max memory regions if backend supports configurable RAM
> slots */
> + if (!virtio_has_feature(dev->protocol_features,
> +
> VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS)) {
> + u->user->memory_slots = VHOST_MEMORY_MAX_NREGIONS;
> + } else {
> + err = vhost_user_get_max_memslots(dev, &ram_slots);
> + if (err < 0) {
> + return err;
> + }
> +
> + if (ram_slots < u->user->memory_slots) {
> + error_report("The backend specified a max ram slots limit
> "
> + "of %lu, when the prior validated limit was
> %d. "
> + "This limit should never decrease.",
> ram_slots,
> + u->user->memory_slots);
> + return -1;
> + }
> +
> + u->user->memory_slots = MIN(ram_slots,
> VHOST_MEMORY_MAX_NREGIONS);
> + }
> }
>
> if (dev->migration_blocker == NULL &&
> @@ -1519,7 +1561,9 @@ static int vhost_user_get_vq_index(struct vhost_dev
> *dev, int idx)
>
> static int vhost_user_memslots_limit(struct vhost_dev *dev)
> {
> - return VHOST_MEMORY_MAX_NREGIONS;
> + struct vhost_user *u = dev->opaque;
> +
> + return u->user->memory_slots;
> }
>
> static bool vhost_user_requires_shm_log(struct vhost_dev *dev)
> @@ -1904,6 +1948,7 @@ bool vhost_user_init(VhostUserState *user,
> CharBackend *chr, Error **errp)
> return false;
> }
> user->chr = chr;
> + user->memory_slots = 0;
> return true;
> }
>
> diff --git a/include/hw/virtio/vhost-user.h
> b/include/hw/virtio/vhost-user.h
> index 811e325..a9abca3 100644
> --- a/include/hw/virtio/vhost-user.h
> +++ b/include/hw/virtio/vhost-user.h
> @@ -20,6 +20,7 @@ typedef struct VhostUserHostNotifier {
> typedef struct VhostUserState {
> CharBackend *chr;
> VhostUserHostNotifier notifier[VIRTIO_QUEUE_MAX];
> + int memory_slots;
> } VhostUserState;
>
> bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error
> **errp);
> --
> 1.8.3.1
>
>
--
Marc-André Lureau
