From patchwork Thu Jan 28 14:41:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Garzarella X-Patchwork-Id: 12053873 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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 1245AC433E0 for ; Thu, 28 Jan 2021 14:52:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC73B64DE9 for ; Thu, 28 Jan 2021 14:52:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231263AbhA1Ovh (ORCPT ); Thu, 28 Jan 2021 09:51:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:50107 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231827AbhA1Onz (ORCPT ); Thu, 28 Jan 2021 09:43:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611844949; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dMfBbPjDPZ4dIyXQtS0tJU0Oae1keECk1ejt9iIRqJg=; b=K3xIJrPl+EiFWyCIoDQuiijp8mdxD4iFqtzs/men9O8zaH3CE7L6AMBzv+/38zbvdTRW8d nM0TzikNGGCK+yOc+e7M6N95z8rmHc35JNPkg1CUVBg6SAir9sB2mO3qoGxK+cSWoHy6Eh 2WSwtXN+10EeYbDITPBRVpuj5aYPiD0= 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-524-UzL0ZiMJPbiRkiCf77zeAA-1; Thu, 28 Jan 2021 09:42:25 -0500 X-MC-Unique: UzL0ZiMJPbiRkiCf77zeAA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CA868801B2E; Thu, 28 Jan 2021 14:42:23 +0000 (UTC) Received: from steredhat.redhat.com (ovpn-113-219.ams2.redhat.com [10.36.113.219]) by smtp.corp.redhat.com (Postfix) with ESMTP id A0F9E19443; Thu, 28 Jan 2021 14:42:05 +0000 (UTC) From: Stefano Garzarella To: virtualization@lists.linux-foundation.org Cc: Xie Yongji , "Michael S. Tsirkin" , Stefano Garzarella , Laurent Vivier , Stefan Hajnoczi , linux-kernel@vger.kernel.org, Max Gurtovoy , Jason Wang , kvm@vger.kernel.org Subject: [PATCH RFC v2 04/10] vringh: implement vringh_kiov_advance() Date: Thu, 28 Jan 2021 15:41:21 +0100 Message-Id: <20210128144127.113245-5-sgarzare@redhat.com> In-Reply-To: <20210128144127.113245-1-sgarzare@redhat.com> References: <20210128144127.113245-1-sgarzare@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org In some cases, it may be useful to provide a way to skip a number of bytes in a vringh_kiov. Let's implement vringh_kiov_advance() for this purpose, reusing the code from vringh_iov_xfer(). We replace that code calling the new vringh_kiov_advance(). Signed-off-by: Stefano Garzarella Acked-by: Jason Wang --- include/linux/vringh.h | 2 ++ drivers/vhost/vringh.c | 41 +++++++++++++++++++++++++++++------------ 2 files changed, 31 insertions(+), 12 deletions(-) diff --git a/include/linux/vringh.h b/include/linux/vringh.h index 9c077863c8f6..755211ebd195 100644 --- a/include/linux/vringh.h +++ b/include/linux/vringh.h @@ -199,6 +199,8 @@ static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov) kiov->iov = NULL; } +void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len); + int vringh_getdesc_kern(struct vringh *vrh, struct vringh_kiov *riov, struct vringh_kiov *wiov, diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c index bee63d68201a..4d800e4f31ca 100644 --- a/drivers/vhost/vringh.c +++ b/drivers/vhost/vringh.c @@ -75,6 +75,34 @@ static inline int __vringh_get_head(const struct vringh *vrh, return head; } +/** + * vringh_kiov_advance - skip bytes from vring_kiov + * @iov: an iov passed to vringh_getdesc_*() (updated as we consume) + * @len: the maximum length to advance + */ +void vringh_kiov_advance(struct vringh_kiov *iov, size_t len) +{ + while (len && iov->i < iov->used) { + size_t partlen = min(iov->iov[iov->i].iov_len, len); + + iov->consumed += partlen; + iov->iov[iov->i].iov_len -= partlen; + iov->iov[iov->i].iov_base += partlen; + + if (!iov->iov[iov->i].iov_len) { + /* Fix up old iov element then increment. */ + iov->iov[iov->i].iov_len = iov->consumed; + iov->iov[iov->i].iov_base -= iov->consumed; + + iov->consumed = 0; + iov->i++; + } + + len -= partlen; + } +} +EXPORT_SYMBOL(vringh_kiov_advance); + /* Copy some bytes to/from the iovec. Returns num copied. */ static inline ssize_t vringh_iov_xfer(struct vringh *vrh, struct vringh_kiov *iov, @@ -95,19 +123,8 @@ static inline ssize_t vringh_iov_xfer(struct vringh *vrh, done += partlen; len -= partlen; ptr += partlen; - iov->consumed += partlen; - iov->iov[iov->i].iov_len -= partlen; - iov->iov[iov->i].iov_base += partlen; - if (!iov->iov[iov->i].iov_len) { - /* Fix up old iov element then increment. */ - iov->iov[iov->i].iov_len = iov->consumed; - iov->iov[iov->i].iov_base -= iov->consumed; - - - iov->consumed = 0; - iov->i++; - } + vringh_kiov_advance(iov, partlen); } return done; }