From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junjie Chen Subject: [PATCH v5] vhost: support virtqueue interrupt/notification suppression Date: Sat, 23 Dec 2017 11:55:53 -0500 Message-ID: <1514048153-82959-1-git-send-email-junjie.j.chen@intel.com> References: <20171128110200.60032-1-junjie.j.chen@intel.com> Cc: dev@dpdk.org, Junjie Chen To: yliu@fridaylinux.org, maxime.coquelin@redhat.com, tiwei.bie@intel.com, xiao.w.wang@intel.com Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 2BABC1B636 for ; Sat, 23 Dec 2017 10:15:18 +0100 (CET) In-Reply-To: <20171128110200.60032-1-junjie.j.chen@intel.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" The driver can suppress interrupt when VIRTIO_F_EVENT_IDX feature bit is negotiated. The driver set vring flags to 0, and MAY use used_event in available ring to advise device interrupt util reach an index specified by used_event. The device ignore the lower bit of vring flags, and send an interrupt when index reach used_event. The device can suppress notification in a manner analogous to the ways driver suppress interrupt. The device manipulates flags or avail_event in the used ringin the same way the driver manipulates flags or used_event in available ring. This patch is to enable this feature in vhost. Signed-off-by: Junjie Chen v5: Remove updating avail event index in backend. v2-v4: Use definition of VIRTIO_F_EVENT_IDX from kernel. --- lib/librte_vhost/Makefile | 1 + lib/librte_vhost/vhost.h | 3 +++ lib/librte_vhost/virtio_net.c | 47 +++++++++++++++++++++++++++++-------------- 3 files changed, 36 insertions(+), 15 deletions(-) diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile index be18279..85695d4 100644 --- a/lib/librte_vhost/Makefile +++ b/lib/librte_vhost/Makefile @@ -40,6 +40,7 @@ LIBABIVER := 4 CFLAGS += $(WERROR_FLAGS) -I$(SRCDIR) -O3 -D_FILE_OFFSET_BITS=64 CFLAGS += -I vhost_user +CFLAGS += -fno-strict-aliasing LDLIBS += -lpthread ifeq ($(CONFIG_RTE_LIBRTE_VHOST_NUMA),y) diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index 1cc81c1..fc41c20 100644 --- a/lib/librte_vhost/vhost.h +++ b/lib/librte_vhost/vhost.h @@ -103,6 +103,8 @@ struct vhost_virtqueue { uint16_t last_avail_idx; uint16_t last_used_idx; + /* Last used index we notify to front end. */ + uint16_t signalled_used; #define VIRTIO_INVALID_EVENTFD (-1) #define VIRTIO_UNINITIALIZED_EVENTFD (-2) @@ -211,6 +213,7 @@ struct vhost_msg { (1ULL << VIRTIO_NET_F_GUEST_TSO4) | \ (1ULL << VIRTIO_NET_F_GUEST_TSO6) | \ (1ULL << VIRTIO_RING_F_INDIRECT_DESC) | \ + (1ULL << VIRTIO_RING_F_EVENT_IDX) | \ (1ULL << VIRTIO_NET_F_MTU) | \ (1ULL << VIRTIO_F_IOMMU_PLATFORM)) diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index 6fee16e..2badeda 100644 --- a/lib/librte_vhost/virtio_net.c +++ b/lib/librte_vhost/virtio_net.c @@ -52,6 +52,35 @@ #define MAX_BATCH_LEN 256 +#define vhost_used_event(vr) ((vr)->avail->ring[(vr)->size]) +#define vhost_avail_event(vr) \ + (*(volatile uint16_t *)&(vr)->used->ring[(vr)->size]) + +static __rte_always_inline void +vhost_notify(struct virtio_net *dev, struct vhost_virtqueue *vq) +{ + /* Don't notify guest if we don't reach index specified by guest. */ + if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) { + uint16_t old = vq->signalled_used; + uint16_t new = vq->last_used_idx; + + LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d, new=%d\n", + __func__, + vhost_used_event(vq), + old, new); + if (vring_need_event(vhost_used_event(vq), new, old) + && (vq->callfd >= 0)) { + vq->signalled_used = vq->last_used_idx; + eventfd_write(vq->callfd, (eventfd_t) 1); + } + } else { + /* Kick the guest if necessary. */ + if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT) + && (vq->callfd >= 0)) + eventfd_write(vq->callfd, (eventfd_t)1); + } +} + static bool is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t nr_vring) { @@ -410,11 +439,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id, /* flush used->idx update before we read avail->flags. */ rte_mb(); - - /* Kick the guest if necessary. */ - if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT) - && (vq->callfd >= 0)) - eventfd_write(vq->callfd, (eventfd_t)1); + vhost_notify(dev, vq); out: if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) vhost_user_iotlb_rd_unlock(vq); @@ -704,11 +729,7 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id, /* flush used->idx update before we read avail->flags. */ rte_mb(); - - /* Kick the guest if necessary. */ - if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT) - && (vq->callfd >= 0)) - eventfd_write(vq->callfd, (eventfd_t)1); + vhost_notify(dev, vq); } out: @@ -1106,11 +1127,7 @@ update_used_idx(struct virtio_net *dev, struct vhost_virtqueue *vq, vq->used->idx += count; vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx), sizeof(vq->used->idx)); - - /* Kick guest if required. */ - if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT) - && (vq->callfd >= 0)) - eventfd_write(vq->callfd, (eventfd_t)1); + vhost_notify(dev, vq); } static __rte_always_inline struct zcopy_mbuf * -- 2.0.1