From patchwork Tue Apr 7 01:07:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 11477103 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 7E6E0913 for ; Tue, 7 Apr 2020 01:07:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5BF492078A for ; Tue, 7 Apr 2020 01:07:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="FoIXAgI5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726679AbgDGBH4 (ORCPT ); Mon, 6 Apr 2020 21:07:56 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:29702 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726659AbgDGBHz (ORCPT ); Mon, 6 Apr 2020 21:07:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586221674; 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: in-reply-to:in-reply-to:references:references; bh=b+P99eoGOE59dzJri6nDdYTRF/iHp1rUM821OiEBSWI=; b=FoIXAgI5OWoA2jtao11ABKn7i0yKHhLWShNWQidugju9gptmfDJxOgQuxG7GoF8Uw99NWi 3NrEIjJwI9EMVTpRKt+jfiK8Na2Q5Z4/PUEXpIHif0/qmyIOiUpOIq6obboECVIAJeQwdA mcz1p8bM7T5bk/xcbFGciGK4MIQSLLI= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-46-BLxZWCsaPZSa0tmgwk5y8g-1; Mon, 06 Apr 2020 21:07:50 -0400 X-MC-Unique: BLxZWCsaPZSa0tmgwk5y8g-1 Received: by mail-wr1-f70.google.com with SMTP id 91so864874wro.1 for ; Mon, 06 Apr 2020 18:07:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=b+P99eoGOE59dzJri6nDdYTRF/iHp1rUM821OiEBSWI=; b=AI0wjgAFO1rFAjFQERpfdWO4InUieslzYRdn/4YBb4NuVlqZd80rhxXqJWYI8Tn3zr ZHTI8mupt+cryqrMXZ7uXwwe4NkI+gKWxXI5GgNp+uXAsV35UlL4DrUHntEKpztw0vsI /7dutoremu9XihvGhOIahQRn1zaDOxdnhe61QLChF4dNkwYfw+aJ2BCcite8/dq+Ne5I gmUOGpnR0omg9mEezAUfEtKFkXwOhHHUG10HXBT5V8ENHWxhTe5F3oLNEueR1c0b6oii UtG0Bp5SUhzew3E7beMi+bgbUbOdkhLWcZZax5nXd/hysJ+WvRpHGO1iGARv4NI7Hpwy jJAg== X-Gm-Message-State: AGi0PuY8VJolNDHNuzNiLzvz1obiYGC/VsHvjnulZ4yD8nfhsx7Yg51F LbQGizI5V3SEEhJmP/w0qyVsVQCeL7oYwplQFI5C9kuK4uHya+f/WUkV+2TV0jHLevnJrZkTfgT 1kUW9NsO8YGL3 X-Received: by 2002:adf:f98b:: with SMTP id f11mr1998832wrr.259.1586221669692; Mon, 06 Apr 2020 18:07:49 -0700 (PDT) X-Google-Smtp-Source: APiQypJ7vAsHxvjmiu+bo7NHbyExOgBSbxXMZd7IkvuAC9tnfoRSEzkPJmWDYEX8+2JgtuNqELnN8w== X-Received: by 2002:adf:f98b:: with SMTP id f11mr1998816wrr.259.1586221669436; Mon, 06 Apr 2020 18:07:49 -0700 (PDT) Received: from redhat.com (bzq-79-176-51-222.red.bezeqint.net. [79.176.51.222]) by smtp.gmail.com with ESMTPSA id j11sm28630487wrt.14.2020.04.06.18.07.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Apr 2020 18:07:48 -0700 (PDT) Date: Mon, 6 Apr 2020 21:07:47 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH v7 10/19] vhost: force spec specified alignment on types Message-ID: <20200407010700.446571-11-mst@redhat.com> References: <20200407010700.446571-1-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200407010700.446571-1-mst@redhat.com> X-Mailer: git-send-email 2.24.1.751.gd10ce2899c X-Mutt-Fcc: =sent Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The ring element addresses are passed between components with different alignments assumptions. Thus, if guest/userspace selects a pointer and host then gets and dereferences it, we might need to decrease the compiler-selected alignment to prevent compiler on the host from assuming pointer is aligned. This actually triggers on ARM with -mabi=apcs-gnu - which is a deprecated configuration, but it seems safer to handle this generally. I verified that the produced binary is exactly identical on x86. Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.h | 6 +++--- include/linux/virtio_ring.h | 24 +++++++++++++++++++++--- 2 files changed, 24 insertions(+), 6 deletions(-) diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index f8403bd46b85..60cab4c78229 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -67,9 +67,9 @@ struct vhost_virtqueue { /* The actual ring of buffers. */ struct mutex mutex; unsigned int num; - struct vring_desc __user *desc; - struct vring_avail __user *avail; - struct vring_used __user *used; + vring_desc_t __user *desc; + vring_avail_t __user *avail; + vring_used_t __user *used; const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS]; struct file *kick; struct eventfd_ctx *call_ctx; diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index 11680e74761a..c3f9ca054250 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -60,14 +60,32 @@ static inline void virtio_store_mb(bool weak_barriers, struct virtio_device; struct virtqueue; +/* + * The ring element addresses are passed between components with different + * alignments assumptions. Thus, we might need to decrease the compiler-selected + * alignment, and so must use a typedef to make sure the __aligned attribute + * actually takes hold: + * + * https://gcc.gnu.org/onlinedocs//gcc/Common-Type-Attributes.html#Common-Type-Attributes + * + * When used on a struct, or struct member, the aligned attribute can only + * increase the alignment; in order to decrease it, the packed attribute must + * be specified as well. When used as part of a typedef, the aligned attribute + * can both increase and decrease alignment, and specifying the packed + * attribute generates a warning. + */ +typedef struct vring_desc __aligned(VRING_DESC_ALIGN_SIZE) vring_desc_t; +typedef struct vring_avail __aligned(VRING_AVAIL_ALIGN_SIZE) vring_avail_t; +typedef struct vring_used __aligned(VRING_USED_ALIGN_SIZE) vring_used_t; + struct vring { unsigned int num; - struct vring_desc *desc; + vring_desc_t *desc; - struct vring_avail *avail; + vring_avail_t *avail; - struct vring_used *used; + vring_used_t *used; }; /* From patchwork Tue Apr 7 01:08:05 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 11477109 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 B577D913 for ; Tue, 7 Apr 2020 01:08:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8045F20719 for ; Tue, 7 Apr 2020 01:08:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Rr7wHW6f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726830AbgDGBIS (ORCPT ); Mon, 6 Apr 2020 21:08:18 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:51434 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726483AbgDGBIQ (ORCPT ); Mon, 6 Apr 2020 21:08:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586221695; 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=lVunxeUGbb+QAKZJYBIWDBklfV6A5oOFLLHt5aVAHSI=; b=Rr7wHW6f8WOBt/btmeCtAJih7b28/kD6OKV1Y1Z4cS4iNVw3bCzPfnxtTdRh7h6qBKt9tk qB9FMrbQzJUPdCdX2VATjQt5mGiFzmQqjsTD769EElwUXp61hR6p2rgGbxSTf4KIlZZuyb mlH8Loh0CxS67JRoyR8b7V0fOL27XnE= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-379-yMRMl3nLPYmNfLXTfa6W8g-1; Mon, 06 Apr 2020 21:08:09 -0400 X-MC-Unique: yMRMl3nLPYmNfLXTfa6W8g-1 Received: by mail-wr1-f71.google.com with SMTP id k11so844685wrm.19 for ; Mon, 06 Apr 2020 18:08:09 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=lVunxeUGbb+QAKZJYBIWDBklfV6A5oOFLLHt5aVAHSI=; b=QDVZ5k2SeNXDlfJqWRMFgQ5dFeW+1rG49ZRf3Gkp7wk5cF93HDy+ej2KcbG/OFZm+t 5x8Y/W/F3k4dM7FMiQrQyDM+rfqr7BlkViRWZAAw0G5g1Q8pyTpC05BZYxX2PTxOQ+RB IfLhrkfAADjMW8j95HYhLueViJjOsi6lQz31cPzvvGWYZ2f0pcQTCUeVkvS2rO9M7dsN NZoq3uVEGxqeCo0Xs/98zN0yvkpObTjDXoLpMe7hqtCgPQYkGpXpPmKmS4secgUan6Bq /7II4hcaanLhB6vKW24IdZo2qoIz3Yj1lxSIwAbWmefrPR3iT0fH2hVj+WIKhz3mqkk/ 3jhQ== X-Gm-Message-State: AGi0Pub6/nBiYZ7t9hog24utT/BLgnKqujyu+dwID6jTWjDPcyNgCwnz O/BkXc1TDDFfJmmn5OlUFap1ghBD8EXoQlw6fR83N4xdhwI/Qd51KDGvv3yI14TJTlidPyD2HdP Di5ZKSFFl/62B X-Received: by 2002:a05:600c:4145:: with SMTP id h5mr2012378wmm.3.1586221688446; Mon, 06 Apr 2020 18:08:08 -0700 (PDT) X-Google-Smtp-Source: APiQypLiaruaXfh56DmzhXrcKdVGS2yMmwHvYBUSYSFl/PpjoQL2J3yP1blfp/v3BjD5XceWEWQakQ== X-Received: by 2002:a05:600c:4145:: with SMTP id h5mr2012338wmm.3.1586221687677; Mon, 06 Apr 2020 18:08:07 -0700 (PDT) Received: from redhat.com (bzq-79-176-51-222.red.bezeqint.net. [79.176.51.222]) by smtp.gmail.com with ESMTPSA id i5sm28025686wrr.12.2020.04.06.18.08.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Apr 2020 18:08:07 -0700 (PDT) Date: Mon, 6 Apr 2020 21:08:05 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Eugenio =?utf-8?b?UMOpcmV6?= , Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH v7 17/19] vhost: option to fetch descriptors through an independent struct Message-ID: <20200407010700.446571-18-mst@redhat.com> References: <20200407010700.446571-1-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200407010700.446571-1-mst@redhat.com> X-Mailer: git-send-email 2.24.1.751.gd10ce2899c X-Mutt-Fcc: =sent Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The idea is to support multiple ring formats by converting to a format-independent array of descriptors. This costs extra cycles, but we gain in ability to fetch a batch of descriptors in one go, which is good for code cache locality. When used, this causes a minor performance degradation, it's been kept as simple as possible for ease of review. A follow-up patch gets us back the performance by adding batching. To simplify benchmarking, I kept the old code around so one can switch back and forth between old and new code. This will go away in the final submission. Signed-off-by: Michael S. Tsirkin Signed-off-by: Eugenio Pérez Link: https://lore.kernel.org/r/20200401183118.8334-2-eperezma@redhat.com Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 297 +++++++++++++++++++++++++++++++++++++++++- drivers/vhost/vhost.h | 16 +++ 2 files changed, 312 insertions(+), 1 deletion(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index d450e16c5c25..56593ba6decc 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -298,6 +298,7 @@ static void vhost_vq_reset(struct vhost_dev *dev, struct vhost_virtqueue *vq) { vq->num = 1; + vq->ndescs = 0; vq->desc = NULL; vq->avail = NULL; vq->used = NULL; @@ -368,6 +369,9 @@ static int vhost_worker(void *data) static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq) { + kfree(vq->descs); + vq->descs = NULL; + vq->max_descs = 0; kfree(vq->indirect); vq->indirect = NULL; kfree(vq->log); @@ -384,6 +388,10 @@ static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) for (i = 0; i < dev->nvqs; ++i) { vq = dev->vqs[i]; + vq->max_descs = dev->iov_limit; + vq->descs = kmalloc_array(vq->max_descs, + sizeof(*vq->descs), + GFP_KERNEL); vq->indirect = kmalloc_array(UIO_MAXIOV, sizeof(*vq->indirect), GFP_KERNEL); @@ -391,7 +399,7 @@ static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) GFP_KERNEL); vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads), GFP_KERNEL); - if (!vq->indirect || !vq->log || !vq->heads) + if (!vq->indirect || !vq->log || !vq->heads || !vq->descs) goto err_nomem; } return 0; @@ -2277,6 +2285,293 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, } EXPORT_SYMBOL_GPL(vhost_get_vq_desc); +static struct vhost_desc *peek_split_desc(struct vhost_virtqueue *vq) +{ + BUG_ON(!vq->ndescs); + return &vq->descs[vq->ndescs - 1]; +} + +static void pop_split_desc(struct vhost_virtqueue *vq) +{ + BUG_ON(!vq->ndescs); + --vq->ndescs; +} + +#define VHOST_DESC_FLAGS (VRING_DESC_F_INDIRECT | VRING_DESC_F_WRITE | \ + VRING_DESC_F_NEXT) +static int push_split_desc(struct vhost_virtqueue *vq, struct vring_desc *desc, u16 id) +{ + struct vhost_desc *h; + + if (unlikely(vq->ndescs >= vq->max_descs)) + return -EINVAL; + h = &vq->descs[vq->ndescs++]; + h->addr = vhost64_to_cpu(vq, desc->addr); + h->len = vhost32_to_cpu(vq, desc->len); + h->flags = vhost16_to_cpu(vq, desc->flags) & VHOST_DESC_FLAGS; + h->id = id; + + return 0; +} + +static int fetch_indirect_descs(struct vhost_virtqueue *vq, + struct vhost_desc *indirect, + u16 head) +{ + struct vring_desc desc; + unsigned int i = 0, count, found = 0; + u32 len = indirect->len; + struct iov_iter from; + int ret; + + /* Sanity check */ + if (unlikely(len % sizeof desc)) { + vq_err(vq, "Invalid length in indirect descriptor: " + "len 0x%llx not multiple of 0x%zx\n", + (unsigned long long)len, + sizeof desc); + return -EINVAL; + } + + ret = translate_desc(vq, indirect->addr, len, vq->indirect, + UIO_MAXIOV, VHOST_ACCESS_RO); + if (unlikely(ret < 0)) { + if (ret != -EAGAIN) + vq_err(vq, "Translation failure %d in indirect.\n", ret); + return ret; + } + iov_iter_init(&from, READ, vq->indirect, ret, len); + + /* We will use the result as an address to read from, so most + * architectures only need a compiler barrier here. */ + read_barrier_depends(); + + count = len / sizeof desc; + /* Buffers are chained via a 16 bit next field, so + * we can have at most 2^16 of these. */ + if (unlikely(count > USHRT_MAX + 1)) { + vq_err(vq, "Indirect buffer length too big: %d\n", + indirect->len); + return -E2BIG; + } + if (unlikely(vq->ndescs + count > vq->max_descs)) { + vq_err(vq, "Too many indirect + direct descs: %d + %d\n", + vq->ndescs, indirect->len); + return -E2BIG; + } + + do { + if (unlikely(++found > count)) { + vq_err(vq, "Loop detected: last one at %u " + "indirect size %u\n", + i, count); + return -EINVAL; + } + if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) { + vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", + i, (size_t)indirect->addr + i * sizeof desc); + return -EINVAL; + } + if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) { + vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", + i, (size_t)indirect->addr + i * sizeof desc); + return -EINVAL; + } + + push_split_desc(vq, &desc, head); + } while ((i = next_desc(vq, &desc)) != -1); + return 0; +} + +static int fetch_descs(struct vhost_virtqueue *vq) +{ + unsigned int i, head, found = 0; + struct vhost_desc *last; + struct vring_desc desc; + __virtio16 avail_idx; + __virtio16 ring_head; + u16 last_avail_idx; + int ret; + + /* Check it isn't doing very strange things with descriptor numbers. */ + last_avail_idx = vq->last_avail_idx; + + if (vq->avail_idx == vq->last_avail_idx) { + if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) { + vq_err(vq, "Failed to access avail idx at %p\n", + &vq->avail->idx); + return -EFAULT; + } + vq->avail_idx = vhost16_to_cpu(vq, avail_idx); + + if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { + vq_err(vq, "Guest moved used index from %u to %u", + last_avail_idx, vq->avail_idx); + return -EFAULT; + } + + /* If there's nothing new since last we looked, return + * invalid. + */ + if (vq->avail_idx == last_avail_idx) + return vq->num; + + /* Only get avail ring entries after they have been + * exposed by guest. + */ + smp_rmb(); + } + + /* Grab the next descriptor number they're advertising */ + if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) { + vq_err(vq, "Failed to read head: idx %d address %p\n", + last_avail_idx, + &vq->avail->ring[last_avail_idx % vq->num]); + return -EFAULT; + } + + head = vhost16_to_cpu(vq, ring_head); + + /* If their number is silly, that's an error. */ + if (unlikely(head >= vq->num)) { + vq_err(vq, "Guest says index %u > %u is available", + head, vq->num); + return -EINVAL; + } + + i = head; + do { + if (unlikely(i >= vq->num)) { + vq_err(vq, "Desc index is %u > %u, head = %u", + i, vq->num, head); + return -EINVAL; + } + if (unlikely(++found > vq->num)) { + vq_err(vq, "Loop detected: last one at %u " + "vq size %u head %u\n", + i, vq->num, head); + return -EINVAL; + } + ret = vhost_get_desc(vq, &desc, i); + if (unlikely(ret)) { + vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", + i, vq->desc + i); + return -EFAULT; + } + ret = push_split_desc(vq, &desc, head); + if (unlikely(ret)) { + vq_err(vq, "Failed to save descriptor: idx %d\n", i); + return -EINVAL; + } + } while ((i = next_desc(vq, &desc)) != -1); + + last = peek_split_desc(vq); + if (unlikely(last->flags & VRING_DESC_F_INDIRECT)) { + pop_split_desc(vq); + ret = fetch_indirect_descs(vq, last, head); + if (unlikely(ret < 0)) { + if (ret != -EAGAIN) + vq_err(vq, "Failure detected " + "in indirect descriptor at idx %d\n", head); + return ret; + } + } + + /* Assume notifications from guest are disabled at this point, + * if they aren't we would need to update avail_event index. */ + BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); + + /* On success, increment avail index. */ + vq->last_avail_idx++; + + return 0; +} + +/* This looks in the virtqueue and for the first available buffer, and converts + * it to an iovec for convenient access. Since descriptors consist of some + * number of output then some number of input descriptors, it's actually two + * iovecs, but we pack them into one and note how many of each there were. + * + * This function returns the descriptor number found, or vq->num (which is + * never a valid descriptor number) if none was found. A negative code is + * returned on error. */ +int vhost_get_vq_desc_batch(struct vhost_virtqueue *vq, + struct iovec iov[], unsigned int iov_size, + unsigned int *out_num, unsigned int *in_num, + struct vhost_log *log, unsigned int *log_num) +{ + int ret = fetch_descs(vq); + int i; + + if (ret) + return ret; + + /* Now convert to IOV */ + /* When we start there are none of either input nor output. */ + *out_num = *in_num = 0; + if (unlikely(log)) + *log_num = 0; + + for (i = 0; i < vq->ndescs; ++i) { + unsigned iov_count = *in_num + *out_num; + struct vhost_desc *desc = &vq->descs[i]; + int access; + + if (desc->flags & ~VHOST_DESC_FLAGS) { + vq_err(vq, "Unexpected flags: 0x%x at descriptor id 0x%x\n", + desc->flags, desc->id); + ret = -EINVAL; + goto err; + } + if (desc->flags & VRING_DESC_F_WRITE) + access = VHOST_ACCESS_WO; + else + access = VHOST_ACCESS_RO; + ret = translate_desc(vq, desc->addr, + desc->len, iov + iov_count, + iov_size - iov_count, access); + if (unlikely(ret < 0)) { + if (ret != -EAGAIN) + vq_err(vq, "Translation failure %d descriptor idx %d\n", + ret, i); + goto err; + } + if (access == VHOST_ACCESS_WO) { + /* If this is an input descriptor, + * increment that count. */ + *in_num += ret; + if (unlikely(log && ret)) { + log[*log_num].addr = desc->addr; + log[*log_num].len = desc->len; + ++*log_num; + } + } else { + /* If it's an output descriptor, they're all supposed + * to come before any input descriptors. */ + if (unlikely(*in_num)) { + vq_err(vq, "Descriptor has out after in: " + "idx %d\n", i); + ret = -EINVAL; + goto err; + } + *out_num += ret; + } + + ret = desc->id; + } + + vq->ndescs = 0; + + return ret; + +err: + vhost_discard_vq_desc(vq, 1); + vq->ndescs = 0; + + return ret; +} +EXPORT_SYMBOL_GPL(vhost_get_vq_desc_batch); + /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) { diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 60cab4c78229..0976a2853935 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -60,6 +60,13 @@ enum vhost_uaddr_type { VHOST_NUM_ADDRS = 3, }; +struct vhost_desc { + u64 addr; + u32 len; + u16 flags; /* VRING_DESC_F_WRITE, VRING_DESC_F_NEXT */ + u16 id; +}; + /* The virtqueue structure describes a queue attached to a device. */ struct vhost_virtqueue { struct vhost_dev *dev; @@ -71,6 +78,11 @@ struct vhost_virtqueue { vring_avail_t __user *avail; vring_used_t __user *used; const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS]; + + struct vhost_desc *descs; + int ndescs; + int max_descs; + struct file *kick; struct eventfd_ctx *call_ctx; struct eventfd_ctx *error_ctx; @@ -175,6 +187,10 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg bool vhost_vq_access_ok(struct vhost_virtqueue *vq); bool vhost_log_access_ok(struct vhost_dev *); +int vhost_get_vq_desc_batch(struct vhost_virtqueue *, + struct iovec iov[], unsigned int iov_count, + unsigned int *out_num, unsigned int *in_num, + struct vhost_log *log, unsigned int *log_num); int vhost_get_vq_desc(struct vhost_virtqueue *, struct iovec iov[], unsigned int iov_count, unsigned int *out_num, unsigned int *in_num, From patchwork Tue Apr 7 01:08:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 11477111 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 374C6159A for ; Tue, 7 Apr 2020 01:08:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B9AF2082F for ; Tue, 7 Apr 2020 01:08:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Mj1o1smv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726952AbgDGBId (ORCPT ); Mon, 6 Apr 2020 21:08:33 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:35807 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726812AbgDGBIS (ORCPT ); Mon, 6 Apr 2020 21:08:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586221696; 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=q8mgU4qPEQl/RF2AoqyTwEFpdBnBeIddoD97BtvkCas=; b=Mj1o1smv3eRlpOaBXVWpVuCYus2d0E0mN9baQXL1Mkt5EmGwe3s0QsFMnbUfzte3I0Hmx8 8onYSBBEPg5xatH0yIKb1s5A+prJcn9lsuOXKs6sUsUdu2dcWOe0dWhMBmIEjQ1cczFVuM QM7KArRfBBBf+AF6kEN8BRthGztA0gk= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-96-HhqB9h8LPx6CBR0lKDXHUw-1; Mon, 06 Apr 2020 21:08:12 -0400 X-MC-Unique: HhqB9h8LPx6CBR0lKDXHUw-1 Received: by mail-wr1-f69.google.com with SMTP id k11so844733wrm.19 for ; Mon, 06 Apr 2020 18:08:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=q8mgU4qPEQl/RF2AoqyTwEFpdBnBeIddoD97BtvkCas=; b=brhLr5WSyjrLSztqTlZHTpqX4sXdlb4rjbvcSnDKAUiP3k146NXD7JN6lNzv4wBbuU 6xxv5hlDhSZWZg0jHRWgsl2jhFM24RbdT5cRdq53GEGKDraHXmH6wM/AwTyjjcEOF3rL uALnYHB8uhmDOQcXTmOrtr1HsugQBZanJPOf0NnoqSDxsgE/V3iYuywHzNQqxlrcnrSy nCAGjbFhIIJZgvcs1cHvbPS1iUJ31Rot80NmE3MdlNWqcGCvHYKIh9T0aMy8iIWulmpR tJbJzGpIAm5fLNYOCruuvHg3t/TJm7pk3YlxK/uKtN3SjHlt5UUuF8HUvcvOHJYLlGvy TTtQ== X-Gm-Message-State: AGi0Puawz1xAIfp7eLSHwj2hIIkq2XBmRDi+fgqQccsa5nLPhnbb4Wnb 5Ihboht1gO33BXrlhFFgytUX1r1adcT1pqZDADKBPyu4phEXqB/fmYLNGPnvyEsZuMpvSuntj0b EAehX221jyM/r X-Received: by 2002:a7b:c2e8:: with SMTP id e8mr815524wmk.43.1586221690728; Mon, 06 Apr 2020 18:08:10 -0700 (PDT) X-Google-Smtp-Source: APiQypIypPOe1A2UK+fGnk4T90k0rEOTNu/mPmn5O73zls1jArL8GfLfVSnO2IgYBJ2V3Co0x85Ejw== X-Received: by 2002:a7b:c2e8:: with SMTP id e8mr815502wmk.43.1586221690385; Mon, 06 Apr 2020 18:08:10 -0700 (PDT) Received: from redhat.com (bzq-79-176-51-222.red.bezeqint.net. [79.176.51.222]) by smtp.gmail.com with ESMTPSA id b199sm104426wme.23.2020.04.06.18.08.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Apr 2020 18:08:09 -0700 (PDT) Date: Mon, 6 Apr 2020 21:08:08 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Eugenio =?utf-8?b?UMOpcmV6?= , Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH v7 18/19] vhost: use batched version by default Message-ID: <20200407010700.446571-19-mst@redhat.com> References: <20200407010700.446571-1-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200407010700.446571-1-mst@redhat.com> X-Mailer: git-send-email 2.24.1.751.gd10ce2899c X-Mutt-Fcc: =sent Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org As testing shows no performance change, switch to that now. Signed-off-by: Michael S. Tsirkin Signed-off-by: Eugenio Pérez Link: https://lore.kernel.org/r/20200401183118.8334-3-eperezma@redhat.com Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 251 +----------------------------------------- drivers/vhost/vhost.h | 4 - 2 files changed, 2 insertions(+), 253 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 56593ba6decc..6ca658c21e15 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -2038,253 +2038,6 @@ static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc) return next; } -static int get_indirect(struct vhost_virtqueue *vq, - struct iovec iov[], unsigned int iov_size, - unsigned int *out_num, unsigned int *in_num, - struct vhost_log *log, unsigned int *log_num, - struct vring_desc *indirect) -{ - struct vring_desc desc; - unsigned int i = 0, count, found = 0; - u32 len = vhost32_to_cpu(vq, indirect->len); - struct iov_iter from; - int ret, access; - - /* Sanity check */ - if (unlikely(len % sizeof desc)) { - vq_err(vq, "Invalid length in indirect descriptor: " - "len 0x%llx not multiple of 0x%zx\n", - (unsigned long long)len, - sizeof desc); - return -EINVAL; - } - - ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect, - UIO_MAXIOV, VHOST_ACCESS_RO); - if (unlikely(ret < 0)) { - if (ret != -EAGAIN) - vq_err(vq, "Translation failure %d in indirect.\n", ret); - return ret; - } - iov_iter_init(&from, READ, vq->indirect, ret, len); - - /* We will use the result as an address to read from, so most - * architectures only need a compiler barrier here. */ - read_barrier_depends(); - - count = len / sizeof desc; - /* Buffers are chained via a 16 bit next field, so - * we can have at most 2^16 of these. */ - if (unlikely(count > USHRT_MAX + 1)) { - vq_err(vq, "Indirect buffer length too big: %d\n", - indirect->len); - return -E2BIG; - } - - do { - unsigned iov_count = *in_num + *out_num; - if (unlikely(++found > count)) { - vq_err(vq, "Loop detected: last one at %u " - "indirect size %u\n", - i, count); - return -EINVAL; - } - if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) { - vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", - i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); - return -EINVAL; - } - if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) { - vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", - i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); - return -EINVAL; - } - - if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) - access = VHOST_ACCESS_WO; - else - access = VHOST_ACCESS_RO; - - ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), - vhost32_to_cpu(vq, desc.len), iov + iov_count, - iov_size - iov_count, access); - if (unlikely(ret < 0)) { - if (ret != -EAGAIN) - vq_err(vq, "Translation failure %d indirect idx %d\n", - ret, i); - return ret; - } - /* If this is an input descriptor, increment that count. */ - if (access == VHOST_ACCESS_WO) { - *in_num += ret; - if (unlikely(log && ret)) { - log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); - log[*log_num].len = vhost32_to_cpu(vq, desc.len); - ++*log_num; - } - } else { - /* If it's an output descriptor, they're all supposed - * to come before any input descriptors. */ - if (unlikely(*in_num)) { - vq_err(vq, "Indirect descriptor " - "has out after in: idx %d\n", i); - return -EINVAL; - } - *out_num += ret; - } - } while ((i = next_desc(vq, &desc)) != -1); - return 0; -} - -/* This looks in the virtqueue and for the first available buffer, and converts - * it to an iovec for convenient access. Since descriptors consist of some - * number of output then some number of input descriptors, it's actually two - * iovecs, but we pack them into one and note how many of each there were. - * - * This function returns the descriptor number found, or vq->num (which is - * never a valid descriptor number) if none was found. A negative code is - * returned on error. */ -int vhost_get_vq_desc(struct vhost_virtqueue *vq, - struct iovec iov[], unsigned int iov_size, - unsigned int *out_num, unsigned int *in_num, - struct vhost_log *log, unsigned int *log_num) -{ - struct vring_desc desc; - unsigned int i, head, found = 0; - u16 last_avail_idx; - __virtio16 avail_idx; - __virtio16 ring_head; - int ret, access; - - /* Check it isn't doing very strange things with descriptor numbers. */ - last_avail_idx = vq->last_avail_idx; - - if (vq->avail_idx == vq->last_avail_idx) { - if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) { - vq_err(vq, "Failed to access avail idx at %p\n", - &vq->avail->idx); - return -EFAULT; - } - vq->avail_idx = vhost16_to_cpu(vq, avail_idx); - - if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { - vq_err(vq, "Guest moved used index from %u to %u", - last_avail_idx, vq->avail_idx); - return -EFAULT; - } - - /* If there's nothing new since last we looked, return - * invalid. - */ - if (vq->avail_idx == last_avail_idx) - return vq->num; - - /* Only get avail ring entries after they have been - * exposed by guest. - */ - smp_rmb(); - } - - /* Grab the next descriptor number they're advertising, and increment - * the index we've seen. */ - if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) { - vq_err(vq, "Failed to read head: idx %d address %p\n", - last_avail_idx, - &vq->avail->ring[last_avail_idx % vq->num]); - return -EFAULT; - } - - head = vhost16_to_cpu(vq, ring_head); - - /* If their number is silly, that's an error. */ - if (unlikely(head >= vq->num)) { - vq_err(vq, "Guest says index %u > %u is available", - head, vq->num); - return -EINVAL; - } - - /* When we start there are none of either input nor output. */ - *out_num = *in_num = 0; - if (unlikely(log)) - *log_num = 0; - - i = head; - do { - unsigned iov_count = *in_num + *out_num; - if (unlikely(i >= vq->num)) { - vq_err(vq, "Desc index is %u > %u, head = %u", - i, vq->num, head); - return -EINVAL; - } - if (unlikely(++found > vq->num)) { - vq_err(vq, "Loop detected: last one at %u " - "vq size %u head %u\n", - i, vq->num, head); - return -EINVAL; - } - ret = vhost_get_desc(vq, &desc, i); - if (unlikely(ret)) { - vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", - i, vq->desc + i); - return -EFAULT; - } - if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) { - ret = get_indirect(vq, iov, iov_size, - out_num, in_num, - log, log_num, &desc); - if (unlikely(ret < 0)) { - if (ret != -EAGAIN) - vq_err(vq, "Failure detected " - "in indirect descriptor at idx %d\n", i); - return ret; - } - continue; - } - - if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) - access = VHOST_ACCESS_WO; - else - access = VHOST_ACCESS_RO; - ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), - vhost32_to_cpu(vq, desc.len), iov + iov_count, - iov_size - iov_count, access); - if (unlikely(ret < 0)) { - if (ret != -EAGAIN) - vq_err(vq, "Translation failure %d descriptor idx %d\n", - ret, i); - return ret; - } - if (access == VHOST_ACCESS_WO) { - /* If this is an input descriptor, - * increment that count. */ - *in_num += ret; - if (unlikely(log && ret)) { - log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); - log[*log_num].len = vhost32_to_cpu(vq, desc.len); - ++*log_num; - } - } else { - /* If it's an output descriptor, they're all supposed - * to come before any input descriptors. */ - if (unlikely(*in_num)) { - vq_err(vq, "Descriptor has out after in: " - "idx %d\n", i); - return -EINVAL; - } - *out_num += ret; - } - } while ((i = next_desc(vq, &desc)) != -1); - - /* On success, increment avail index. */ - vq->last_avail_idx++; - - /* Assume notifications from guest are disabled at this point, - * if they aren't we would need to update avail_event index. */ - BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); - return head; -} -EXPORT_SYMBOL_GPL(vhost_get_vq_desc); - static struct vhost_desc *peek_split_desc(struct vhost_virtqueue *vq) { BUG_ON(!vq->ndescs); @@ -2495,7 +2248,7 @@ static int fetch_descs(struct vhost_virtqueue *vq) * This function returns the descriptor number found, or vq->num (which is * never a valid descriptor number) if none was found. A negative code is * returned on error. */ -int vhost_get_vq_desc_batch(struct vhost_virtqueue *vq, +int vhost_get_vq_desc(struct vhost_virtqueue *vq, struct iovec iov[], unsigned int iov_size, unsigned int *out_num, unsigned int *in_num, struct vhost_log *log, unsigned int *log_num) @@ -2570,7 +2323,7 @@ int vhost_get_vq_desc_batch(struct vhost_virtqueue *vq, return ret; } -EXPORT_SYMBOL_GPL(vhost_get_vq_desc_batch); +EXPORT_SYMBOL_GPL(vhost_get_vq_desc); /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 0976a2853935..76356edee8e5 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -187,10 +187,6 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg bool vhost_vq_access_ok(struct vhost_virtqueue *vq); bool vhost_log_access_ok(struct vhost_dev *); -int vhost_get_vq_desc_batch(struct vhost_virtqueue *, - struct iovec iov[], unsigned int iov_count, - unsigned int *out_num, unsigned int *in_num, - struct vhost_log *log, unsigned int *log_num); int vhost_get_vq_desc(struct vhost_virtqueue *, struct iovec iov[], unsigned int iov_count, unsigned int *out_num, unsigned int *in_num, From patchwork Tue Apr 7 01:08:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 11477107 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 C7BB6159A for ; Tue, 7 Apr 2020 01:08:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C8052078C for ; Tue, 7 Apr 2020 01:08:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="T6oXOIBo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726909AbgDGBIZ (ORCPT ); Mon, 6 Apr 2020 21:08:25 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:46157 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726841AbgDGBIT (ORCPT ); Mon, 6 Apr 2020 21:08:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586221698; 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=L4yUJTneo14gmnV6yvCsrtosUccNNJJsj0HwyG8nxy8=; b=T6oXOIBo7XvYJa/9UWCfTjIKd9QoVDCQZmzyE49SelC5SrQC0/5Ew6O75JvYRe+ZDxbFCD z3URrq6hrJkkR1EDDDsGLjG4SZ876+q6ldX68gdGiVi2Ct9Fn3RmpTIOBaJEQgTyDhZJvr ESrhtlVmuaBB7khZoWy/5C8HkM5hur4= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-468-RERv3eXKNrKz4M5etTV7LA-1; Mon, 06 Apr 2020 21:08:14 -0400 X-MC-Unique: RERv3eXKNrKz4M5etTV7LA-1 Received: by mail-wr1-f70.google.com with SMTP id d4so854268wrq.10 for ; Mon, 06 Apr 2020 18:08:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=L4yUJTneo14gmnV6yvCsrtosUccNNJJsj0HwyG8nxy8=; b=kn8+M7nyY+pgcrh620Nd99Wzy/0VJt24WEn/nX/SHJk1zqC5pz28UYOEkq7DFr3AH3 A4jc/NXrsqhFzg6t9c+MF54eaqpw7eROqq3SUea/PxIbOtzTZnQwLqIhEEUk52ulHJf7 A9rvbWvhJ7XRF8wI5tRmbhX3oMjocZXogAp9BugCQOvb/TjeACrP5hgej9QvGHujsaN0 xebA7bYRhx4d1m8Sjtvpb0rvEeFsrPJ2PZp68ORBneb9s9W+fSk8aCHaPKF1WW4Y7/UH o+GWgG++4MKWyW5P+WP5d7Gb1kWoDD7R5HlJgnel16RdHpXzyFVbaDGRqU8OLJAmybDR S2Sw== X-Gm-Message-State: AGi0PuY6PdrKLQhG25Bdzb5u/ayBplX+q02Cu1FY0wt+KTV1/XAP8Whq JyjB2ySed3j/fiEzs30u4Fyqog54WygrWmNLjdcIVBA1dlbgKCN/xIvEp/niBGskUXbYHJ4QcoZ jbtm7EjLlgtcv X-Received: by 2002:a5d:4ac2:: with SMTP id y2mr2231410wrs.340.1586221692865; Mon, 06 Apr 2020 18:08:12 -0700 (PDT) X-Google-Smtp-Source: APiQypJRyp/ZpJacQiZ3k9H+aTIpbKPM4w8UFFPSIqcFT0rwHZZkPHnvafzAm6P2M2/gPs/IswWSoA== X-Received: by 2002:a5d:4ac2:: with SMTP id y2mr2231387wrs.340.1586221692600; Mon, 06 Apr 2020 18:08:12 -0700 (PDT) Received: from redhat.com (bzq-79-176-51-222.red.bezeqint.net. [79.176.51.222]) by smtp.gmail.com with ESMTPSA id c17sm23267693wrp.28.2020.04.06.18.08.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Apr 2020 18:08:12 -0700 (PDT) Date: Mon, 6 Apr 2020 21:08:10 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Eugenio =?utf-8?b?UMOpcmV6?= , Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH v7 19/19] vhost: batching fetches Message-ID: <20200407010700.446571-20-mst@redhat.com> References: <20200407010700.446571-1-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200407010700.446571-1-mst@redhat.com> X-Mailer: git-send-email 2.24.1.751.gd10ce2899c X-Mutt-Fcc: =sent Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org With this patch applied, new and old code perform identically. Lots of extra optimizations are now possible, e.g. we can fetch multiple heads with copy_from/to_user now. We can get rid of maintaining the log array. Etc etc. Signed-off-by: Michael S. Tsirkin Signed-off-by: Eugenio Pérez Link: https://lore.kernel.org/r/20200401183118.8334-4-eperezma@redhat.com Signed-off-by: Michael S. Tsirkin --- drivers/vhost/test.c | 2 +- drivers/vhost/vhost.c | 47 ++++++++++++++++++++++++++++++++++++++----- drivers/vhost/vhost.h | 5 ++++- 3 files changed, 47 insertions(+), 7 deletions(-) diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c index b06680833f03..251ca723ac3f 100644 --- a/drivers/vhost/test.c +++ b/drivers/vhost/test.c @@ -119,7 +119,7 @@ static int vhost_test_open(struct inode *inode, struct file *f) dev = &n->dev; vqs[VHOST_TEST_VQ] = &n->vqs[VHOST_TEST_VQ]; n->vqs[VHOST_TEST_VQ].handle_kick = handle_vq_kick; - vhost_dev_init(dev, vqs, VHOST_TEST_VQ_MAX, UIO_MAXIOV, + vhost_dev_init(dev, vqs, VHOST_TEST_VQ_MAX, UIO_MAXIOV + 64, VHOST_TEST_PKT_WEIGHT, VHOST_TEST_WEIGHT, NULL); f->private_data = n; diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 6ca658c21e15..0395229486a9 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -299,6 +299,7 @@ static void vhost_vq_reset(struct vhost_dev *dev, { vq->num = 1; vq->ndescs = 0; + vq->first_desc = 0; vq->desc = NULL; vq->avail = NULL; vq->used = NULL; @@ -367,6 +368,11 @@ static int vhost_worker(void *data) return 0; } +static int vhost_vq_num_batch_descs(struct vhost_virtqueue *vq) +{ + return vq->max_descs - UIO_MAXIOV; +} + static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq) { kfree(vq->descs); @@ -389,6 +395,9 @@ static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) for (i = 0; i < dev->nvqs; ++i) { vq = dev->vqs[i]; vq->max_descs = dev->iov_limit; + if (vhost_vq_num_batch_descs(vq) < 0) { + return -EINVAL; + } vq->descs = kmalloc_array(vq->max_descs, sizeof(*vq->descs), GFP_KERNEL); @@ -1570,6 +1579,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg vq->last_avail_idx = s.num; /* Forget the cached index value. */ vq->avail_idx = vq->last_avail_idx; + vq->ndescs = vq->first_desc = 0; break; case VHOST_GET_VRING_BASE: s.index = idx; @@ -2136,7 +2146,7 @@ static int fetch_indirect_descs(struct vhost_virtqueue *vq, return 0; } -static int fetch_descs(struct vhost_virtqueue *vq) +static int fetch_buf(struct vhost_virtqueue *vq) { unsigned int i, head, found = 0; struct vhost_desc *last; @@ -2149,7 +2159,11 @@ static int fetch_descs(struct vhost_virtqueue *vq) /* Check it isn't doing very strange things with descriptor numbers. */ last_avail_idx = vq->last_avail_idx; - if (vq->avail_idx == vq->last_avail_idx) { + if (unlikely(vq->avail_idx == vq->last_avail_idx)) { + /* If we already have work to do, don't bother re-checking. */ + if (likely(vq->ndescs)) + return vq->num; + if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) { vq_err(vq, "Failed to access avail idx at %p\n", &vq->avail->idx); @@ -2240,6 +2254,24 @@ static int fetch_descs(struct vhost_virtqueue *vq) return 0; } +static int fetch_descs(struct vhost_virtqueue *vq) +{ + int ret = 0; + + if (unlikely(vq->first_desc >= vq->ndescs)) { + vq->first_desc = 0; + vq->ndescs = 0; + } + + if (vq->ndescs) + return 0; + + while (!ret && vq->ndescs <= vhost_vq_num_batch_descs(vq)) + ret = fetch_buf(vq); + + return vq->ndescs ? 0 : ret; +} + /* This looks in the virtqueue and for the first available buffer, and converts * it to an iovec for convenient access. Since descriptors consist of some * number of output then some number of input descriptors, it's actually two @@ -2265,7 +2297,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, if (unlikely(log)) *log_num = 0; - for (i = 0; i < vq->ndescs; ++i) { + for (i = vq->first_desc; i < vq->ndescs; ++i) { unsigned iov_count = *in_num + *out_num; struct vhost_desc *desc = &vq->descs[i]; int access; @@ -2311,14 +2343,19 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, } ret = desc->id; + + if (!(desc->flags & VRING_DESC_F_NEXT)) + break; } - vq->ndescs = 0; + vq->first_desc = i + 1; return ret; err: - vhost_discard_vq_desc(vq, 1); + for (i = vq->first_desc; i < vq->ndescs; ++i) + if (!(vq->descs[i].flags & VRING_DESC_F_NEXT)) + vhost_discard_vq_desc(vq, 1); vq->ndescs = 0; return ret; diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 76356edee8e5..a67bda9792ec 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -81,6 +81,7 @@ struct vhost_virtqueue { struct vhost_desc *descs; int ndescs; + int first_desc; int max_descs; struct file *kick; @@ -229,7 +230,7 @@ void vhost_iotlb_map_free(struct vhost_iotlb *iotlb, struct vhost_iotlb_map *map); #define vq_err(vq, fmt, ...) do { \ - pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ + pr_err(pr_fmt(fmt), ##__VA_ARGS__); \ if ((vq)->error_ctx) \ eventfd_signal((vq)->error_ctx, 1);\ } while (0) @@ -255,6 +256,8 @@ static inline void vhost_vq_set_backend(struct vhost_virtqueue *vq, void *private_data) { vq->private_data = private_data; + vq->ndescs = 0; + vq->first_desc = 0; } /**