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[109.64.41.91]) by smtp.gmail.com with ESMTPSA id m129sm3760204wmf.2.2020.06.02.06.05.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jun 2020 06:06:00 -0700 (PDT) Date: Tue, 2 Jun 2020 09:05:59 -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 RFC 02/13] vhost: use batched version by default Message-ID: <20200602130543.578420-3-mst@redhat.com> References: <20200602130543.578420-1-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200602130543.578420-1-mst@redhat.com> X-Mailer: git-send-email 2.24.1.751.gd10ce2899c X-Mutt-Fcc: =sent Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 105fc97af2c8..8f9a07282625 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, -- MST