From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754150AbeDWFgF (ORCPT ); Mon, 23 Apr 2018 01:36:05 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44248 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754105AbeDWFfv (ORCPT ); Mon, 23 Apr 2018 01:35:51 -0400 From: Jason Wang To: mst@redhat.com, jasowang@redhat.com Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, tiwei.bie@intel.com, jfreimann@redhat.com, wexu@redhat.com Subject: [RFC V3 PATCH 8/8] vhost: event suppression for packed ring Date: Mon, 23 Apr 2018 13:35:00 +0800 Message-Id: <1524461700-5469-9-git-send-email-jasowang@redhat.com> In-Reply-To: <1524461700-5469-1-git-send-email-jasowang@redhat.com> References: <1524461700-5469-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch introduces basic support for event suppression aka driver and device area. Signed-off-by: Jason Wang --- drivers/vhost/vhost.c | 170 ++++++++++++++++++++++++++++++++++++--- drivers/vhost/vhost.h | 10 ++- include/uapi/linux/virtio_ring.h | 19 +++++ 3 files changed, 184 insertions(+), 15 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 7759441..53a4673 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1143,10 +1143,15 @@ static int vq_access_ok_packed(struct vhost_virtqueue *vq, unsigned int num, struct vring_used __user *used) { struct vring_desc_packed *packed = (struct vring_desc_packed *)desc; + struct vring_packed_desc_event *driver_event = + (struct vring_packed_desc_event *)avail; + struct vring_packed_desc_event *device_event = + (struct vring_packed_desc_event *)used; - /* FIXME: check device area and driver area */ return access_ok(VERIFY_READ, packed, num * sizeof(*packed)) && - access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)); + access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)) && + access_ok(VERIFY_READ, driver_event, sizeof(*driver_event)) && + access_ok(VERIFY_WRITE, device_event, sizeof(*device_event)); } static int vq_access_ok_split(struct vhost_virtqueue *vq, unsigned int num, @@ -1221,14 +1226,27 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq, return true; } -int vq_iotlb_prefetch(struct vhost_virtqueue *vq) +int vq_iotlb_prefetch_packed(struct vhost_virtqueue *vq) +{ + int num = vq->num; + + return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc, + num * sizeof(*vq->desc), VHOST_ADDR_DESC) && + iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->desc, + num * sizeof(*vq->desc), VHOST_ADDR_DESC) && + iotlb_access_ok(vq, VHOST_ACCESS_RO, + (u64)(uintptr_t)vq->driver_event, + sizeof(*vq->driver_event), VHOST_ADDR_AVAIL) && + iotlb_access_ok(vq, VHOST_ACCESS_WO, + (u64)(uintptr_t)vq->device_event, + sizeof(*vq->device_event), VHOST_ADDR_USED); +} + +int vq_iotlb_prefetch_split(struct vhost_virtqueue *vq) { size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; unsigned int num = vq->num; - if (!vq->iotlb) - return 1; - return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc, num * sizeof(*vq->desc), VHOST_ADDR_DESC) && iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail, @@ -1240,6 +1258,17 @@ int vq_iotlb_prefetch(struct vhost_virtqueue *vq) num * sizeof(*vq->used->ring) + s, VHOST_ADDR_USED); } + +int vq_iotlb_prefetch(struct vhost_virtqueue *vq) +{ + if (!vq->iotlb) + return 1; + + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) + return vq_iotlb_prefetch_packed(vq); + else + return vq_iotlb_prefetch_split(vq); +} EXPORT_SYMBOL_GPL(vq_iotlb_prefetch); /* Can we log writes? */ @@ -1755,6 +1784,29 @@ static int vhost_update_used_flags(struct vhost_virtqueue *vq) return 0; } +static int vhost_update_device_flags(struct vhost_virtqueue *vq, + __virtio16 device_flags) +{ + void __user *flags; + + if (vhost_put_user(vq, cpu_to_vhost16(vq, device_flags), + &vq->device_event->desc_event_flags, + VHOST_ADDR_USED) < 0) + return -EFAULT; + if (unlikely(vq->log_used)) { + /* Make sure the flag is seen before log. */ + smp_wmb(); + /* Log used flag write. */ + flags = &vq->device_event->desc_event_flags; + log_write(vq->log_base, vq->log_addr + + (flags - (void __user *)vq->device_event), + sizeof(vq->used->flags)); + if (vq->log_ctx) + eventfd_signal(vq->log_ctx, 1); + } + return 0; +} + static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) { if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx), @@ -2671,16 +2723,13 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, } EXPORT_SYMBOL_GPL(vhost_add_used_n); -static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) +static bool vhost_notify_split(struct vhost_dev *dev, + struct vhost_virtqueue *vq) { __u16 old, new; __virtio16 event; bool v; - /* FIXME: check driver area */ - if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) - return false; - /* Flush out used index updates. This is paired * with the barrier that the Guest executes when enabling * interrupts. */ @@ -2713,6 +2762,80 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) return vring_need_event(vhost16_to_cpu(vq, event), new, old); } +static u16 vhost_idx_diff(struct vhost_virtqueue *vq, u16 old, u16 new) +{ + if (new > old) + return new - old; + return (new + vq->num - old); +} + +static bool vhost_vring_packed_need_event(struct vhost_virtqueue *vq, + __u16 event_off, __u16 new, + __u16 old) +{ + return (__u16)(vhost_idx_diff(vq, new, event_off) - 1) < + (__u16)vhost_idx_diff(vq, new, old); +} + +static bool vhost_notify_packed(struct vhost_dev *dev, + struct vhost_virtqueue *vq) +{ + __virtio16 event_off_wrap, event_flags; + __u16 old, new; + bool v, wrap; + int off; + + /* Flush out used descriptors updates. This is paired + * with the barrier that the Guest executes when enabling + * interrupts. + */ + smp_mb(); + + if (vhost_get_avail(vq, event_flags, + &vq->driver_event->desc_event_flags) < 0) { + vq_err(vq, "Failed to get driver desc_event_flags"); + return true; + } + + if (event_flags == cpu_to_vhost16(vq, RING_EVENT_FLAGS_DISABLE)) + return false; + else if (event_flags == cpu_to_vhost16(vq, RING_EVENT_FLAGS_ENABLE)) + return true; + + /* Read desc event flags before event_off and event_wrap */ + smp_rmb(); + + if (vhost_get_avail(vq, event_off_wrap, + &vq->driver_event->desc_event_off_warp) < 0) { + vq_err(vq, "Failed to get driver desc_event_off/wrap"); + return true; + } + + off = vhost16_to_cpu(vq, event_off_wrap); + + wrap = off >> 15; + off = off & ~((1 << 15) - 1); + + old = vq->signalled_used; + v = vq->signalled_used_valid; + new = vq->signalled_used = vq->last_used_idx; + vq->signalled_used_valid = true; + + if (unlikely(!v)) + return true; + + return vhost_vring_packed_need_event(vq, new, old, off) && + wrap == vq->used_wrap_counter; +} + +static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) +{ + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) + return vhost_notify_packed(dev, vq); + else + return vhost_notify_split(dev, vq); +} + /* This actually signals the guest, using eventfd. */ void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) { @@ -2793,7 +2916,17 @@ static bool vhost_enable_notify_packed(struct vhost_dev *dev, __virtio16 flags; int ret; - /* FIXME: disable notification through device area */ + if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) + return false; + vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; + + flags = cpu_to_vhost16(vq, RING_EVENT_FLAGS_ENABLE); + ret = vhost_update_device_flags(vq, flags); + if (ret) { + vq_err(vq, "Failed to enable notification at %p: %d\n", + &vq->device_event->desc_event_flags, ret); + return false; + } /* They could have slipped one in as we were doing that: make * sure it's written, then check again. */ @@ -2859,7 +2992,18 @@ EXPORT_SYMBOL_GPL(vhost_enable_notify); static void vhost_disable_notify_packed(struct vhost_dev *dev, struct vhost_virtqueue *vq) { - /* FIXME: disable notification through device area */ + __virtio16 flags; + int r; + + if (vq->used_flags & VRING_USED_F_NO_NOTIFY) + return; + vq->used_flags |= VRING_USED_F_NO_NOTIFY; + + flags = cpu_to_vhost16(vq, RING_EVENT_FLAGS_DISABLE); + r = vhost_update_device_flags(vq, flags); + if (r) + vq_err(vq, "Failed to enable notification at %p: %d\n", + &vq->device_event->desc_event_flags, r); } static void vhost_disable_notify_split(struct vhost_dev *dev, diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 286b470..0750659 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -96,8 +96,14 @@ struct vhost_virtqueue { struct vring_desc __user *desc; struct vring_desc_packed __user *desc_packed; }; - struct vring_avail __user *avail; - struct vring_used __user *used; + union { + struct vring_avail __user *avail; + struct vring_packed_desc_event __user *driver_event; + }; + union { + struct vring_used __user *used; + struct vring_packed_desc_event __user *device_event; + }; const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS]; struct file *kick; struct eventfd_ctx *call_ctx; diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h index e297580..7cdbf06 100644 --- a/include/uapi/linux/virtio_ring.h +++ b/include/uapi/linux/virtio_ring.h @@ -75,6 +75,25 @@ struct vring_desc_packed { __virtio16 flags; }; +/* Enable events */ +#define RING_EVENT_FLAGS_ENABLE 0x0 +/* Disable events */ +#define RING_EVENT_FLAGS_DISABLE 0x1 +/* + * Enable events for a specific descriptor + * (as specified by Descriptor Ring Change Event Offset/Wrap Counter). + * Only valid if VIRTIO_F_RING_EVENT_IDX has been negotiated. + */ +#define RING_EVENT_FLAGS_DESC 0x2 +/* The value 0x3 is reserved */ + +struct vring_packed_desc_event { + /* Descriptor Ring Change Event Offset and Wrap Counter */ + __virtio16 desc_event_off_warp; + /* Descriptor Ring Change Event Flags */ + __virtio16 desc_event_flags; +}; + /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ struct vring_desc { /* Address (guest-physical). */ -- 2.7.4