From patchwork Mon Mar 15 19:48:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eugenio Perez Martin X-Patchwork-Id: 12140583 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76E3BC433E0 for ; Mon, 15 Mar 2021 19:57:23 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C491964EF3 for ; Mon, 15 Mar 2021 19:57:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C491964EF3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43040 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lLtL7-0006iV-HI for qemu-devel@archiver.kernel.org; Mon, 15 Mar 2021 15:57:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37836) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lLtDt-0005oO-VS for qemu-devel@nongnu.org; Mon, 15 Mar 2021 15:49:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:26015) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lLtDr-0004Bm-EN for qemu-devel@nongnu.org; Mon, 15 Mar 2021 15:49:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615837790; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u9cqwMQ+rFXawpf7AL1LTcnF7tvSq1hGLTxiqTMVF4Q=; b=LasuY81j4WWfl+keqSN3HD8ZiBSoqEz/D/N6zin7+k8a+ZSagmWRIEsZlnj0+0zTrPR+9T xeYHEJPaUjpLESbRSFPnEDx4u4RvXGn4n+MPE2AFrazdyGiz/zjWVf1WU/SgntL2mELs8M kZa6JuOJJ6uPUA+HbnZpm+EnFY7t+D0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-441-tZnxKVtWNuGC17YXl0FjGQ-1; Mon, 15 Mar 2021 15:49:49 -0400 X-MC-Unique: tZnxKVtWNuGC17YXl0FjGQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2F262108BD07; Mon, 15 Mar 2021 19:49:47 +0000 (UTC) Received: from eperezma.remote.csb (ovpn-112-173.ams2.redhat.com [10.36.112.173]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9D7125F9B8; Mon, 15 Mar 2021 19:49:43 +0000 (UTC) From: =?utf-8?q?Eugenio_P=C3=A9rez?= To: qemu-devel@nongnu.org Subject: [RFC v2 11/13] vhost: Shadow virtqueue buffers forwarding Date: Mon, 15 Mar 2021 20:48:40 +0100 Message-Id: <20210315194842.277740-12-eperezma@redhat.com> In-Reply-To: <20210315194842.277740-1-eperezma@redhat.com> References: <20210315194842.277740-1-eperezma@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eperezma@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=eperezma@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.25, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Parav Pandit , "Michael S. Tsirkin" , Guru Prasad , Jason Wang , Juan Quintela , Markus Armbruster , virtualization@lists.linux-foundation.org, Harpreet Singh Anand , Xiao W Wang , Eli Cohen , Stefano Garzarella , Michael Lilja , Jim Harford , Rob Miller Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Initial version of shadow virtqueue that actually forward buffers. It reuses the VirtQueue code for the device part. The driver part is based on Linux's virtio_ring driver, but with stripped functionality and optimizations so it's easier to review. These will be added in later commits. Signed-off-by: Eugenio Pérez --- hw/virtio/vhost-shadow-virtqueue.c | 212 +++++++++++++++++++++++++++-- hw/virtio/vhost.c | 113 ++++++++++++++- 2 files changed, 312 insertions(+), 13 deletions(-) diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c index 1460d1d5d1..68ed0f2740 100644 --- a/hw/virtio/vhost-shadow-virtqueue.c +++ b/hw/virtio/vhost-shadow-virtqueue.c @@ -9,6 +9,7 @@ #include "hw/virtio/vhost-shadow-virtqueue.h" #include "hw/virtio/vhost.h" +#include "hw/virtio/virtio-access.h" #include "standard-headers/linux/vhost_types.h" @@ -55,11 +56,96 @@ typedef struct VhostShadowVirtqueue { /* Virtio device */ VirtIODevice *vdev; + /* Map for returning guest's descriptors */ + VirtQueueElement **ring_id_maps; + + /* Next head to expose to device */ + uint16_t avail_idx_shadow; + + /* Next free descriptor */ + uint16_t free_head; + + /* Last seen used idx */ + uint16_t shadow_used_idx; + + /* Next head to consume from device */ + uint16_t used_idx; + /* Descriptors copied from guest */ vring_desc_t descs[]; } VhostShadowVirtqueue; -/* Forward guest notifications */ +static void vhost_vring_write_descs(VhostShadowVirtqueue *svq, + const struct iovec *iovec, + size_t num, bool more_descs, bool write) +{ + uint16_t i = svq->free_head, last = svq->free_head; + unsigned n; + uint16_t flags = write ? virtio_tswap16(svq->vdev, VRING_DESC_F_WRITE) : 0; + vring_desc_t *descs = svq->vring.desc; + + if (num == 0) { + return; + } + + for (n = 0; n < num; n++) { + if (more_descs || (n + 1 < num)) { + descs[i].flags = flags | virtio_tswap16(svq->vdev, + VRING_DESC_F_NEXT); + } else { + descs[i].flags = flags; + } + descs[i].addr = virtio_tswap64(svq->vdev, (hwaddr)iovec[n].iov_base); + descs[i].len = virtio_tswap32(svq->vdev, iovec[n].iov_len); + + last = i; + i = virtio_tswap16(svq->vdev, descs[i].next); + } + + svq->free_head = virtio_tswap16(svq->vdev, descs[last].next); +} + +static unsigned vhost_shadow_vq_add_split(VhostShadowVirtqueue *svq, + VirtQueueElement *elem) +{ + int head; + unsigned avail_idx; + vring_avail_t *avail = svq->vring.avail; + + head = svq->free_head; + + /* We need some descriptors here */ + assert(elem->out_num || elem->in_num); + + vhost_vring_write_descs(svq, elem->out_sg, elem->out_num, + elem->in_num > 0, false); + vhost_vring_write_descs(svq, elem->in_sg, elem->in_num, false, true); + + /* + * Put entry in available array (but don't update avail->idx until they + * do sync). + */ + avail_idx = svq->avail_idx_shadow & (svq->vring.num - 1); + avail->ring[avail_idx] = virtio_tswap16(svq->vdev, head); + svq->avail_idx_shadow++; + + /* Expose descriptors to device */ + smp_wmb(); + avail->idx = virtio_tswap16(svq->vdev, svq->avail_idx_shadow); + + return head; + +} + +static void vhost_shadow_vq_add(VhostShadowVirtqueue *svq, + VirtQueueElement *elem) +{ + unsigned qemu_head = vhost_shadow_vq_add_split(svq, elem); + + svq->ring_id_maps[qemu_head] = elem; +} + +/* Handle guest->device notifications */ static void vhost_handle_guest_kick(EventNotifier *n) { VhostShadowVirtqueue *svq = container_of(n, VhostShadowVirtqueue, @@ -69,7 +155,72 @@ static void vhost_handle_guest_kick(EventNotifier *n) return; } - event_notifier_set(&svq->kick_notifier); + /* Make available as many buffers as possible */ + do { + if (virtio_queue_get_notification(svq->vq)) { + /* No more notifications until process all available */ + virtio_queue_set_notification(svq->vq, false); + } + + while (true) { + VirtQueueElement *elem; + if (virtio_queue_full(svq->vq)) { + break; + } + + elem = virtqueue_pop(svq->vq, sizeof(*elem)); + if (!elem) { + break; + } + + vhost_shadow_vq_add(svq, elem); + event_notifier_set(&svq->kick_notifier); + } + + virtio_queue_set_notification(svq->vq, true); + } while (!virtio_queue_empty(svq->vq)); +} + +static bool vhost_shadow_vq_more_used(VhostShadowVirtqueue *svq) +{ + if (svq->used_idx != svq->shadow_used_idx) { + return true; + } + + /* Get used idx must not be reordered */ + smp_rmb(); + svq->shadow_used_idx = virtio_tswap16(svq->vdev, svq->vring.used->idx); + + return svq->used_idx != svq->shadow_used_idx; +} + +static VirtQueueElement *vhost_shadow_vq_get_buf(VhostShadowVirtqueue *svq) +{ + vring_desc_t *descs = svq->vring.desc; + const vring_used_t *used = svq->vring.used; + vring_used_elem_t used_elem; + uint16_t last_used; + + if (!vhost_shadow_vq_more_used(svq)) { + return NULL; + } + + last_used = svq->used_idx & (svq->vring.num - 1); + used_elem.id = virtio_tswap32(svq->vdev, used->ring[last_used].id); + used_elem.len = virtio_tswap32(svq->vdev, used->ring[last_used].len); + + if (unlikely(used_elem.id >= svq->vring.num)) { + error_report("Device %s says index %u is available", svq->vdev->name, + used_elem.id); + return NULL; + } + + descs[used_elem.id].next = svq->free_head; + svq->free_head = used_elem.id; + + svq->used_idx++; + svq->ring_id_maps[used_elem.id]->len = used_elem.len; + return g_steal_pointer(&svq->ring_id_maps[used_elem.id]); } /* Forward vhost notifications */ @@ -78,6 +229,7 @@ static void vhost_shadow_vq_handle_call_no_test(EventNotifier *n) VhostShadowVirtqueue *svq = container_of(n, VhostShadowVirtqueue, call_notifier); EventNotifier *masked_notifier; + VirtQueue *vq = svq->vq; /* Signal start of using masked notifier */ qemu_event_reset(&svq->masked_notifier.is_free); @@ -86,14 +238,29 @@ static void vhost_shadow_vq_handle_call_no_test(EventNotifier *n) qemu_event_set(&svq->masked_notifier.is_free); } - if (!masked_notifier) { - unsigned n = virtio_get_queue_index(svq->vq); - virtio_queue_invalidate_signalled_used(svq->vdev, n); - virtio_notify_irqfd(svq->vdev, svq->vq); - } else if (!svq->masked_notifier.signaled) { - svq->masked_notifier.signaled = true; - event_notifier_set(svq->masked_notifier.n); - } + /* Make as many buffers as possible used. */ + do { + unsigned i = 0; + + /* TODO: Use VRING_AVAIL_F_NO_INTERRUPT */ + while (true) { + g_autofree VirtQueueElement *elem = vhost_shadow_vq_get_buf(svq); + if (!elem) { + break; + } + + assert(i < svq->vring.num); + virtqueue_fill(vq, elem, elem->len, i++); + } + + virtqueue_flush(vq, i); + if (!masked_notifier) { + virtio_notify_irqfd(svq->vdev, svq->vq); + } else if (!svq->masked_notifier.signaled) { + svq->masked_notifier.signaled = true; + event_notifier_set(svq->masked_notifier.n); + } + } while (vhost_shadow_vq_more_used(svq)); if (masked_notifier) { /* Signal not using it anymore */ @@ -103,7 +270,6 @@ static void vhost_shadow_vq_handle_call_no_test(EventNotifier *n) static void vhost_shadow_vq_handle_call(EventNotifier *n) { - if (likely(event_notifier_test_and_clear(n))) { vhost_shadow_vq_handle_call_no_test(n); } @@ -254,7 +420,11 @@ void vhost_shadow_vq_stop(struct vhost_dev *dev, unsigned idx, VhostShadowVirtqueue *svq) { + int i; int r = vhost_shadow_vq_restore_vdev_host_notifier(dev, idx, svq); + + assert(!dev->shadow_vqs_enabled); + if (unlikely(r < 0)) { error_report("Couldn't restore vq kick fd: %s", strerror(-r)); } @@ -272,6 +442,18 @@ void vhost_shadow_vq_stop(struct vhost_dev *dev, /* Restore vhost call */ vhost_virtqueue_mask(dev, dev->vdev, dev->vq_index + idx, dev->vqs[idx].notifier_is_masked); + + + for (i = 0; i < svq->vring.num; ++i) { + g_autofree VirtQueueElement *elem = svq->ring_id_maps[i]; + /* + * Although the doc says we must unpop in order, it's ok to unpop + * everything. + */ + if (elem) { + virtqueue_unpop(svq->vq, elem, elem->len); + } + } } /* @@ -284,7 +466,7 @@ VhostShadowVirtqueue *vhost_shadow_vq_new(struct vhost_dev *dev, int idx) unsigned num = virtio_queue_get_num(dev->vdev, vq_idx); size_t ring_size = vring_size(num, VRING_DESC_ALIGN_SIZE); g_autofree VhostShadowVirtqueue *svq = g_malloc0(sizeof(*svq) + ring_size); - int r; + int r, i; r = event_notifier_init(&svq->kick_notifier, 0); if (r != 0) { @@ -303,6 +485,11 @@ VhostShadowVirtqueue *vhost_shadow_vq_new(struct vhost_dev *dev, int idx) vring_init(&svq->vring, num, svq->descs, VRING_DESC_ALIGN_SIZE); svq->vq = virtio_get_queue(dev->vdev, vq_idx); svq->vdev = dev->vdev; + for (i = 0; i < num - 1; i++) { + svq->descs[i].next = virtio_tswap16(dev->vdev, i + 1); + } + + svq->ring_id_maps = g_new0(VirtQueueElement *, num); event_notifier_set_handler(&svq->call_notifier, vhost_shadow_vq_handle_call); qemu_event_init(&svq->masked_notifier.is_free, true); @@ -324,5 +511,6 @@ void vhost_shadow_vq_free(VhostShadowVirtqueue *vq) event_notifier_cleanup(&vq->kick_notifier); event_notifier_set_handler(&vq->call_notifier, NULL); event_notifier_cleanup(&vq->call_notifier); + g_free(vq->ring_id_maps); g_free(vq); } diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index eab3e334f2..a373999bc4 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -1021,6 +1021,19 @@ int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write) trace_vhost_iotlb_miss(dev, 1); + if (qatomic_load_acquire(&dev->shadow_vqs_enabled)) { + uaddr = iova; + len = 4096; + ret = vhost_backend_update_device_iotlb(dev, iova, uaddr, len, + IOMMU_RW); + if (ret) { + trace_vhost_iotlb_miss(dev, 2); + error_report("Fail to update device iotlb"); + } + + return ret; + } + iotlb = address_space_get_iotlb_entry(dev->vdev->dma_as, iova, write, MEMTXATTRS_UNSPECIFIED); @@ -1227,8 +1240,28 @@ static int vhost_sw_live_migration_stop(struct vhost_dev *dev) /* Can be read by vhost_virtqueue_mask, from vm exit */ qatomic_store_release(&dev->shadow_vqs_enabled, false); + dev->vhost_ops->vhost_set_vring_enable(dev, false); + if (vhost_backend_invalidate_device_iotlb(dev, 0, -1ULL)) { + error_report("Fail to invalidate device iotlb"); + } + for (idx = 0; idx < dev->nvqs; ++idx) { + /* + * Update used ring information for IOTLB to work correctly, + * vhost-kernel code requires for this. + */ + struct vhost_virtqueue *vq = dev->vqs + idx; + vhost_device_iotlb_miss(dev, vq->used_phys, true); + vhost_shadow_vq_stop(dev, idx, dev->shadow_vqs[idx]); + vhost_virtqueue_start(dev, dev->vdev, &dev->vqs[idx], + dev->vq_index + idx); + } + + /* Enable guest's vq vring */ + dev->vhost_ops->vhost_set_vring_enable(dev, true); + + for (idx = 0; idx < dev->nvqs; ++idx) { vhost_shadow_vq_free(dev->shadow_vqs[idx]); } @@ -1237,6 +1270,59 @@ static int vhost_sw_live_migration_stop(struct vhost_dev *dev) return 0; } +/* + * Start shadow virtqueue in a given queue. + * In failure case, this function leaves queue working as regular vhost mode. + */ +static bool vhost_sw_live_migration_start_vq(struct vhost_dev *dev, + unsigned idx) +{ + struct vhost_vring_addr addr = { + .index = idx, + }; + struct vhost_vring_state s = { + .index = idx, + }; + int r; + bool ok; + + vhost_virtqueue_stop(dev, dev->vdev, &dev->vqs[idx], dev->vq_index + idx); + ok = vhost_shadow_vq_start(dev, idx, dev->shadow_vqs[idx]); + if (unlikely(!ok)) { + return false; + } + + /* From this point, vhost_virtqueue_start can reset these changes */ + vhost_shadow_vq_get_vring_addr(dev->shadow_vqs[idx], &addr); + r = dev->vhost_ops->vhost_set_vring_addr(dev, &addr); + if (unlikely(r != 0)) { + VHOST_OPS_DEBUG("vhost_set_vring_addr for shadow vq failed"); + goto err; + } + + r = dev->vhost_ops->vhost_set_vring_base(dev, &s); + if (unlikely(r != 0)) { + VHOST_OPS_DEBUG("vhost_set_vring_base for shadow vq failed"); + goto err; + } + + /* + * Update used ring information for IOTLB to work correctly, + * vhost-kernel code requires for this. + */ + r = vhost_device_iotlb_miss(dev, addr.used_user_addr, true); + if (unlikely(r != 0)) { + /* Debug message already printed */ + goto err; + } + + return true; + +err: + vhost_virtqueue_start(dev, dev->vdev, &dev->vqs[idx], dev->vq_index + idx); + return false; +} + static int vhost_sw_live_migration_start(struct vhost_dev *dev) { int idx, stop_idx; @@ -1249,24 +1335,35 @@ static int vhost_sw_live_migration_start(struct vhost_dev *dev) } } + dev->vhost_ops->vhost_set_vring_enable(dev, false); + if (vhost_backend_invalidate_device_iotlb(dev, 0, -1ULL)) { + error_report("Fail to invalidate device iotlb"); + } + /* Can be read by vhost_virtqueue_mask, from vm exit */ qatomic_store_release(&dev->shadow_vqs_enabled, true); for (idx = 0; idx < dev->nvqs; ++idx) { - bool ok = vhost_shadow_vq_start(dev, idx, dev->shadow_vqs[idx]); + bool ok = vhost_sw_live_migration_start_vq(dev, idx); if (unlikely(!ok)) { goto err_start; } } + /* Enable shadow vq vring */ + dev->vhost_ops->vhost_set_vring_enable(dev, true); return 0; err_start: qatomic_store_release(&dev->shadow_vqs_enabled, false); for (stop_idx = 0; stop_idx < idx; stop_idx++) { vhost_shadow_vq_stop(dev, idx, dev->shadow_vqs[stop_idx]); + vhost_virtqueue_start(dev, dev->vdev, &dev->vqs[idx], + dev->vq_index + stop_idx); } err_new: + /* Enable guest's vring */ + dev->vhost_ops->vhost_set_vring_enable(dev, true); for (idx = 0; idx < dev->nvqs; ++idx) { vhost_shadow_vq_free(dev->shadow_vqs[idx]); } @@ -1970,6 +2067,20 @@ void qmp_x_vhost_enable_shadow_vq(const char *name, bool enable, Error **errp) if (!hdev->started) { err_cause = "Device is not started"; + } else if (!vhost_dev_has_iommu(hdev)) { + err_cause = "Does not support iommu"; + } else if (hdev->acked_features & BIT_ULL(VIRTIO_F_RING_PACKED)) { + err_cause = "Is packed"; + } else if (hdev->acked_features & BIT_ULL(VIRTIO_RING_F_EVENT_IDX)) { + err_cause = "Have event idx"; + } else if (hdev->acked_features & + BIT_ULL(VIRTIO_RING_F_INDIRECT_DESC)) { + err_cause = "Supports indirect descriptors"; + } else if (!hdev->vhost_ops->vhost_set_vring_enable) { + err_cause = "Cannot pause device"; + } + + if (err_cause) { goto err; }