From patchwork Thu Sep 5 12:27:36 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Wang X-Patchwork-Id: 11133009 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A9B3C1395 for ; Thu, 5 Sep 2019 12:28:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77EEF22DD3 for ; Thu, 5 Sep 2019 12:28:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389400AbfIEM15 (ORCPT ); Thu, 5 Sep 2019 08:27:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2369 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389393AbfIEM15 (ORCPT ); Thu, 5 Sep 2019 08:27:57 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C0B2F3060288; Thu, 5 Sep 2019 12:27:55 +0000 (UTC) Received: from jason-ThinkPad-X1-Carbon-6th.redhat.com (ovpn-12-44.pek2.redhat.com [10.72.12.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id E57405D9E1; Thu, 5 Sep 2019 12:27:50 +0000 (UTC) From: Jason Wang To: mst@redhat.com, jasowang@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jgg@mellanox.com, aarcange@redhat.com, jglisse@redhat.com, linux-mm@kvack.org, James Bottomley , Christoph Hellwig , David Miller , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org Subject: [PATCH 2/2] vhost: re-introducing metadata acceleration through kernel virtual address Date: Thu, 5 Sep 2019 20:27:36 +0800 Message-Id: <20190905122736.19768-3-jasowang@redhat.com> In-Reply-To: <20190905122736.19768-1-jasowang@redhat.com> References: <20190905122736.19768-1-jasowang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Thu, 05 Sep 2019 12:27:56 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org This is a rework on the commit 7f466032dc9e ("vhost: access vq metadata through kernel virtual address"). It was noticed that the copy_to/from_user() friends that was used to access virtqueue metdata tends to be very expensive for dataplane implementation like vhost since it involves lots of software checks, speculation barriers, hardware feature toggling (e.g SMAP). The extra cost will be more obvious when transferring small packets since the time spent on metadata accessing become more significant. This patch tries to eliminate those overheads by accessing them through direct mapping of those pages. Invalidation callbacks is implemented for co-operation with general VM management (swap, KSM, THP or NUMA balancing). We will try to get the direct mapping of vq metadata before each round of packet processing if it doesn't exist. If we fail, we will simplely fallback to copy_to/from_user() friends. This invalidation, direct mapping access and set are synchronized through spinlock. This takes a step back from the original commit 7f466032dc9e ("vhost: access vq metadata through kernel virtual address") which tries to RCU which is suspicious and hard to be reviewed. This won't perform as well as RCU because of the atomic, this could be addressed by the future optimization. This method might does not work for high mem page which requires temporary mapping so we just fallback to normal copy_to/from_user() and may not for arch that has virtual tagged cache since extra cache flushing is needed to eliminate the alias. This will result complex logic and bad performance. For those archs, this patch simply go for copy_to/from_user() friends. This is done by ruling out kernel mapping codes through ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE. Note that this is only done when device IOTLB is not enabled. We could use similar method to optimize IOTLB in the future. Tests shows at most about 22% improvement on TX PPS when using virtio-user + vhost_net + xdp1 + TAP on 4.0GHz Kaby Lake. SMAP on | SMAP off Before: 4.9Mpps | 6.9Mpps After: 6.0Mpps | 7.5Mpps On a elder CPU Sandy Bridge without SMAP support. TX PPS doesn't see any difference. Cc: Andrea Arcangeli Cc: James Bottomley Cc: Christoph Hellwig Cc: David Miller Cc: Jerome Glisse Cc: Jason Gunthorpe Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-parisc@vger.kernel.org Signed-off-by: Jason Wang Signed-off-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 551 +++++++++++++++++++++++++++++++++++++++++- drivers/vhost/vhost.h | 41 ++++ 2 files changed, 589 insertions(+), 3 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 791562e03fe0..f98155f28f02 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -298,6 +298,182 @@ static void vhost_vq_meta_reset(struct vhost_dev *d) __vhost_vq_meta_reset(d->vqs[i]); } +#if VHOST_ARCH_CAN_ACCEL_UACCESS +static void vhost_map_unprefetch(struct vhost_map *map) +{ + kfree(map->pages); + kfree(map); +} + +static void vhost_set_map_dirty(struct vhost_virtqueue *vq, + struct vhost_map *map, int index) +{ + struct vhost_uaddr *uaddr = &vq->uaddrs[index]; + int i; + + if (uaddr->write) { + for (i = 0; i < map->npages; i++) + set_page_dirty(map->pages[i]); + } +} + +static void vhost_uninit_vq_maps(struct vhost_virtqueue *vq) +{ + struct vhost_map *map[VHOST_NUM_ADDRS]; + int i; + + spin_lock(&vq->mmu_lock); + for (i = 0; i < VHOST_NUM_ADDRS; i++) { + map[i] = vq->maps[i]; + if (map[i]) { + vhost_set_map_dirty(vq, map[i], i); + vq->maps[i] = NULL; + } + } + spin_unlock(&vq->mmu_lock); + + /* No need for synchronization since we are serialized with + * memory accessors (e.g vq mutex held). + */ + + for (i = 0; i < VHOST_NUM_ADDRS; i++) + if (map[i]) + vhost_map_unprefetch(map[i]); + +} + +static void vhost_reset_vq_maps(struct vhost_virtqueue *vq) +{ + int i; + + vhost_uninit_vq_maps(vq); + for (i = 0; i < VHOST_NUM_ADDRS; i++) + vq->uaddrs[i].size = 0; +} + +static bool vhost_map_range_overlap(struct vhost_uaddr *uaddr, + unsigned long start, + unsigned long end) +{ + if (unlikely(!uaddr->size)) + return false; + + return !(end < uaddr->uaddr || start > uaddr->uaddr - 1 + uaddr->size); +} + +static void inline vhost_vq_access_map_begin(struct vhost_virtqueue *vq) +{ + spin_lock(&vq->mmu_lock); +} + +static void inline vhost_vq_access_map_end(struct vhost_virtqueue *vq) +{ + spin_unlock(&vq->mmu_lock); +} + +static int vhost_invalidate_vq_start(struct vhost_virtqueue *vq, + int index, + unsigned long start, + unsigned long end, + bool blockable) +{ + struct vhost_uaddr *uaddr = &vq->uaddrs[index]; + struct vhost_map *map; + + if (!vhost_map_range_overlap(uaddr, start, end)) + return 0; + else if (!blockable) + return -EAGAIN; + + spin_lock(&vq->mmu_lock); + ++vq->invalidate_count; + + map = vq->maps[index]; + if (map) + vq->maps[index] = NULL; + spin_unlock(&vq->mmu_lock); + + if (map) { + vhost_set_map_dirty(vq, map, index); + vhost_map_unprefetch(map); + } + + return 0; +} + +static void vhost_invalidate_vq_end(struct vhost_virtqueue *vq, + int index, + unsigned long start, + unsigned long end) +{ + if (!vhost_map_range_overlap(&vq->uaddrs[index], start, end)) + return; + + spin_lock(&vq->mmu_lock); + --vq->invalidate_count; + spin_unlock(&vq->mmu_lock); +} + +static int vhost_invalidate_range_start(struct mmu_notifier *mn, + const struct mmu_notifier_range *range) +{ + struct vhost_dev *dev = container_of(mn, struct vhost_dev, + mmu_notifier); + bool blockable = mmu_notifier_range_blockable(range); + int i, j, ret; + + for (i = 0; i < dev->nvqs; i++) { + struct vhost_virtqueue *vq = dev->vqs[i]; + + for (j = 0; j < VHOST_NUM_ADDRS; j++) { + ret = vhost_invalidate_vq_start(vq, j, + range->start, + range->end, blockable); + if (ret) + return ret; + } + } + + return 0; +} + +static void vhost_invalidate_range_end(struct mmu_notifier *mn, + const struct mmu_notifier_range *range) +{ + struct vhost_dev *dev = container_of(mn, struct vhost_dev, + mmu_notifier); + int i, j; + + for (i = 0; i < dev->nvqs; i++) { + struct vhost_virtqueue *vq = dev->vqs[i]; + + for (j = 0; j < VHOST_NUM_ADDRS; j++) + vhost_invalidate_vq_end(vq, j, + range->start, + range->end); + } +} + +static const struct mmu_notifier_ops vhost_mmu_notifier_ops = { + .invalidate_range_start = vhost_invalidate_range_start, + .invalidate_range_end = vhost_invalidate_range_end, +}; + +static void vhost_init_maps(struct vhost_dev *dev) +{ + struct vhost_virtqueue *vq; + int i, j; + + dev->mmu_notifier.ops = &vhost_mmu_notifier_ops; + + for (i = 0; i < dev->nvqs; ++i) { + vq = dev->vqs[i]; + for (j = 0; j < VHOST_NUM_ADDRS; j++) + vq->maps[j] = NULL; + } +} +#endif + static void vhost_vq_reset(struct vhost_dev *dev, struct vhost_virtqueue *vq) { @@ -326,7 +502,11 @@ static void vhost_vq_reset(struct vhost_dev *dev, vq->busyloop_timeout = 0; vq->umem = NULL; vq->iotlb = NULL; + vq->invalidate_count = 0; __vhost_vq_meta_reset(vq); +#if VHOST_ARCH_CAN_ACCEL_UACCESS + vhost_reset_vq_maps(vq); +#endif } static int vhost_worker(void *data) @@ -471,12 +651,15 @@ void vhost_dev_init(struct vhost_dev *dev, dev->iov_limit = iov_limit; dev->weight = weight; dev->byte_weight = byte_weight; + dev->has_notifier = false; init_llist_head(&dev->work_list); init_waitqueue_head(&dev->wait); INIT_LIST_HEAD(&dev->read_list); INIT_LIST_HEAD(&dev->pending_list); spin_lock_init(&dev->iotlb_lock); - +#if VHOST_ARCH_CAN_ACCEL_UACCESS + vhost_init_maps(dev); +#endif for (i = 0; i < dev->nvqs; ++i) { vq = dev->vqs[i]; @@ -485,6 +668,7 @@ void vhost_dev_init(struct vhost_dev *dev, vq->heads = NULL; vq->dev = dev; mutex_init(&vq->mutex); + spin_lock_init(&vq->mmu_lock); vhost_vq_reset(dev, vq); if (vq->handle_kick) vhost_poll_init(&vq->poll, vq->handle_kick, @@ -564,7 +748,19 @@ long vhost_dev_set_owner(struct vhost_dev *dev) if (err) goto err_cgroup; +#if VHOST_ARCH_CAN_ACCEL_UACCESS + err = mmu_notifier_register(&dev->mmu_notifier, dev->mm); + if (err) + goto err_mmu_notifier; +#endif + dev->has_notifier = true; + return 0; + +#if VHOST_ARCH_CAN_ACCEL_UACCESS +err_mmu_notifier: + vhost_dev_free_iovecs(dev); +#endif err_cgroup: kthread_stop(worker); dev->worker = NULL; @@ -655,6 +851,107 @@ static void vhost_clear_msg(struct vhost_dev *dev) spin_unlock(&dev->iotlb_lock); } +#if VHOST_ARCH_CAN_ACCEL_UACCESS +static void vhost_setup_uaddr(struct vhost_virtqueue *vq, + int index, unsigned long uaddr, + size_t size, bool write) +{ + struct vhost_uaddr *addr = &vq->uaddrs[index]; + + addr->uaddr = uaddr; + addr->size = size; + addr->write = write; +} + +static void vhost_setup_vq_uaddr(struct vhost_virtqueue *vq) +{ + vhost_setup_uaddr(vq, VHOST_ADDR_DESC, + (unsigned long)vq->desc, + vhost_get_desc_size(vq, vq->num), + false); + vhost_setup_uaddr(vq, VHOST_ADDR_AVAIL, + (unsigned long)vq->avail, + vhost_get_avail_size(vq, vq->num), + false); + vhost_setup_uaddr(vq, VHOST_ADDR_USED, + (unsigned long)vq->used, + vhost_get_used_size(vq, vq->num), + true); +} + +static int vhost_map_prefetch(struct vhost_virtqueue *vq, + int index) +{ + struct vhost_map *map; + struct vhost_uaddr *uaddr = &vq->uaddrs[index]; + struct page **pages; + int npages = DIV_ROUND_UP(uaddr->size, PAGE_SIZE); + int npinned; + void *vaddr, *v; + int err; + int i; + + spin_lock(&vq->mmu_lock); + + err = -EFAULT; + if (vq->invalidate_count) + goto err; + + err = -ENOMEM; + map = kmalloc(sizeof(*map), GFP_ATOMIC); + if (!map) + goto err; + + pages = kmalloc_array(npages, sizeof(struct page *), GFP_ATOMIC); + if (!pages) + goto err_pages; + + err = EFAULT; + npinned = __get_user_pages_fast(uaddr->uaddr, npages, + uaddr->write, pages); + if (npinned > 0) + release_pages(pages, npinned); + if (npinned != npages) + goto err_gup; + + for (i = 0; i < npinned; i++) + if (PageHighMem(pages[i])) + goto err_gup; + + vaddr = v = page_address(pages[0]); + + /* For simplicity, fallback to userspace address if VA is not + * contigious. + */ + for (i = 1; i < npinned; i++) { + v += PAGE_SIZE; + if (v != page_address(pages[i])) + goto err_gup; + } + + map->addr = vaddr + (uaddr->uaddr & (PAGE_SIZE - 1)); + map->npages = npages; + map->pages = pages; + + vq->maps[index] = map; + /* No need for a synchronize_rcu(). This function should be + * called by dev->worker so we are serialized with all + * readers. + */ + spin_unlock(&vq->mmu_lock); + + return 0; + +err_gup: + kfree(pages); +err_pages: + kfree(map); +err: + spin_unlock(&vq->mmu_lock); + return err; +} +#endif + void vhost_dev_cleanup(struct vhost_dev *dev) { int i; @@ -684,8 +981,20 @@ void vhost_dev_cleanup(struct vhost_dev *dev) kthread_stop(dev->worker); dev->worker = NULL; } - if (dev->mm) + if (dev->mm) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + if (dev->has_notifier) { + mmu_notifier_unregister(&dev->mmu_notifier, + dev->mm); + dev->has_notifier = false; + } +#endif mmput(dev->mm); + } +#if VHOST_ARCH_CAN_ACCEL_UACCESS + for (i = 0; i < dev->nvqs; i++) + vhost_uninit_vq_maps(dev->vqs[i]); +#endif dev->mm = NULL; } EXPORT_SYMBOL_GPL(vhost_dev_cleanup); @@ -914,6 +1223,26 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq, static inline int vhost_put_avail_event(struct vhost_virtqueue *vq) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_used *used; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_USED]; + if (likely(map)) { + used = map->addr; + *((__virtio16 *)&used->ring[vq->num]) = + cpu_to_vhost16(vq, vq->avail_idx); + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq)); } @@ -922,6 +1251,27 @@ static inline int vhost_put_used(struct vhost_virtqueue *vq, struct vring_used_elem *head, int idx, int count) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_used *used; + size_t size; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_USED]; + if (likely(map)) { + used = map->addr; + size = count * sizeof(*head); + memcpy(used->ring + idx, head, size); + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_copy_to_user(vq, vq->used->ring + idx, head, count * sizeof(*head)); } @@ -929,6 +1279,25 @@ static inline int vhost_put_used(struct vhost_virtqueue *vq, static inline int vhost_put_used_flags(struct vhost_virtqueue *vq) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_used *used; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_USED]; + if (likely(map)) { + used = map->addr; + used->flags = cpu_to_vhost16(vq, vq->used_flags); + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags); } @@ -936,6 +1305,25 @@ static inline int vhost_put_used_flags(struct vhost_virtqueue *vq) static inline int vhost_put_used_idx(struct vhost_virtqueue *vq) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_used *used; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_USED]; + if (likely(map)) { + used = map->addr; + used->idx = cpu_to_vhost16(vq, vq->last_used_idx); + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx); } @@ -981,12 +1369,50 @@ static void vhost_dev_unlock_vqs(struct vhost_dev *d) static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq, __virtio16 *idx) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_avail *avail; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_AVAIL]; + if (likely(map)) { + avail = map->addr; + *idx = avail->idx; + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_get_avail(vq, *idx, &vq->avail->idx); } static inline int vhost_get_avail_head(struct vhost_virtqueue *vq, __virtio16 *head, int idx) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_avail *avail; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_AVAIL]; + if (likely(map)) { + avail = map->addr; + *head = avail->ring[idx & (vq->num - 1)]; + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_get_avail(vq, *head, &vq->avail->ring[idx & (vq->num - 1)]); } @@ -994,24 +1420,98 @@ static inline int vhost_get_avail_head(struct vhost_virtqueue *vq, static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq, __virtio16 *flags) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_avail *avail; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_AVAIL]; + if (likely(map)) { + avail = map->addr; + *flags = avail->flags; + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_get_avail(vq, *flags, &vq->avail->flags); } static inline int vhost_get_used_event(struct vhost_virtqueue *vq, __virtio16 *event) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_avail *avail; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + map = vq->maps[VHOST_ADDR_AVAIL]; + if (likely(map)) { + avail = map->addr; + *event = (__virtio16)avail->ring[vq->num]; + vhost_vq_access_map_end(vq); + return 0; + } + vhost_vq_access_map_end(vq); + } +#endif + return vhost_get_avail(vq, *event, vhost_used_event(vq)); } static inline int vhost_get_used_idx(struct vhost_virtqueue *vq, __virtio16 *idx) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_used *used; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_USED]; + if (likely(map)) { + used = map->addr; + *idx = used->idx; + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_get_used(vq, *idx, &vq->used->idx); } static inline int vhost_get_desc(struct vhost_virtqueue *vq, struct vring_desc *desc, int idx) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + struct vhost_map *map; + struct vring_desc *d; + + if (!vq->iotlb) { + vhost_vq_access_map_begin(vq); + + map = vq->maps[VHOST_ADDR_DESC]; + if (likely(map)) { + d = map->addr; + *desc = *(d + idx); + vhost_vq_access_map_end(vq); + return 0; + } + + vhost_vq_access_map_end(vq); + } +#endif + return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc)); } @@ -1352,12 +1852,30 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq, return true; } +#if VHOST_ARCH_CAN_ACCEL_UACCESS +static void vhost_vq_map_prefetch(struct vhost_virtqueue *vq) +{ + struct vhost_map *map; + int i; + + for (i = 0; i < VHOST_NUM_ADDRS; i++) { + map = vq->maps[i]; + if (unlikely(!map)) + vhost_map_prefetch(vq, i); + } +} +#endif + int vq_meta_prefetch(struct vhost_virtqueue *vq) { unsigned int num = vq->num; - if (!vq->iotlb) + if (!vq->iotlb) { +#if VHOST_ARCH_CAN_ACCEL_UACCESS + vhost_vq_map_prefetch(vq); +#endif return 1; + } return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc, vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) && @@ -1568,6 +2086,22 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d, mutex_lock(&vq->mutex); +#if VHOST_ARCH_CAN_ACCEL_UACCESS + /* Unregister MMU notifer to allow invalidation callback + * can access vq->uaddrs[] without holding a lock. + */ + if (d->has_notifier) { + mmu_notifier_unregister(&d->mmu_notifier, d->mm); + d->has_notifier = false; + } + + /* reset invalidate_count in case we are in the middle of + * invalidate_start() and invalidate_end(). + */ + vq->invalidate_count = 0; + vhost_uninit_vq_maps(vq); +#endif + switch (ioctl) { case VHOST_SET_VRING_NUM: r = vhost_vring_set_num(d, vq, argp); @@ -1579,6 +2113,17 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d, BUG(); } +#if VHOST_ARCH_CAN_ACCEL_UACCESS + if (r == 0) + vhost_setup_vq_uaddr(vq); + + if (d->mm) { + r = mmu_notifier_register(&d->mmu_notifier, d->mm); + if (!r) + d->has_notifier = true; + } +#endif + mutex_unlock(&vq->mutex); return r; diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index e9ed2722b633..85e97e0f77f5 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -12,6 +12,9 @@ #include #include #include +#include +#include +#include struct vhost_work; typedef void (*vhost_work_fn_t)(struct vhost_work *work); @@ -80,6 +83,24 @@ enum vhost_uaddr_type { VHOST_NUM_ADDRS = 3, }; +struct vhost_map { + int npages; + void *addr; + struct page **pages; +}; + +struct vhost_uaddr { + unsigned long uaddr; + size_t size; + bool write; +}; + +#if defined(CONFIG_MMU_NOTIFIER) && ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 0 +#define VHOST_ARCH_CAN_ACCEL_UACCESS 1 +#else +#define VHOST_ARCH_CAN_ACCEL_UACCESS 0 +#endif + /* The virtqueue structure describes a queue attached to a device. */ struct vhost_virtqueue { struct vhost_dev *dev; @@ -90,7 +111,21 @@ struct vhost_virtqueue { struct vring_desc __user *desc; struct vring_avail __user *avail; struct vring_used __user *used; + +#if VHOST_ARCH_CAN_ACCEL_UACCESS + /* Read by memory accessors, modified by meta data + * prefetching, MMU notifier and vring ioctl(). + * Synchonrized through mmu_lock. + */ + struct vhost_map *maps[VHOST_NUM_ADDRS]; + /* Read by MMU notifier, modified by vring ioctl(), + * synchronized through MMU notifier + * registering/unregistering. + */ + struct vhost_uaddr uaddrs[VHOST_NUM_ADDRS]; +#endif const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS]; + struct file *kick; struct eventfd_ctx *call_ctx; struct eventfd_ctx *error_ctx; @@ -145,6 +180,8 @@ struct vhost_virtqueue { bool user_be; #endif u32 busyloop_timeout; + spinlock_t mmu_lock; + int invalidate_count; }; struct vhost_msg_node { @@ -158,6 +195,9 @@ struct vhost_msg_node { struct vhost_dev { struct mm_struct *mm; +#ifdef CONFIG_MMU_NOTIFIER + struct mmu_notifier mmu_notifier; +#endif struct mutex mutex; struct vhost_virtqueue **vqs; int nvqs; @@ -173,6 +213,7 @@ struct vhost_dev { int iov_limit; int weight; int byte_weight; + bool has_notifier; }; bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);