From mboxrd@z Thu Jan 1 00:00:00 1970 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=-17.2 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=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 291DBC4332F for ; Wed, 22 Sep 2021 17:09:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 15E8E611C9 for ; Wed, 22 Sep 2021 17:09:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236809AbhIVRKt (ORCPT ); Wed, 22 Sep 2021 13:10:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25982 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236747AbhIVRKp (ORCPT ); Wed, 22 Sep 2021 13:10:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632330555; 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=hmVOjxLeJWEmyCqfs0Tb1bLYB+sc0BhB8/yHgn5Iolk=; b=NFJ+lvJDYXbr2yQeflrPOW6TpbA7T39DbgfbrcBaYAg5NdphkcUDxlC3BHXk72e+JLVadG KxthsGuUYvT6eATb39mzrHGbtxiq+EQTqJQstyYe0Y1ZL/6jJ707LsxHAqI7Cdpq1WIxID l1CvaplwsMf/ryFu2jM7Skf0LNU58Kk= 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-259-JbM5iIzSMG2_Abmdmd-yZg-1; Wed, 22 Sep 2021 13:09:13 -0400 X-MC-Unique: JbM5iIzSMG2_Abmdmd-yZg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 382AD79EDD; Wed, 22 Sep 2021 17:09:12 +0000 (UTC) Received: from thinkpad.redhat.com (unknown [10.39.192.105]) by smtp.corp.redhat.com (Postfix) with ESMTP id E7430970E1; Wed, 22 Sep 2021 17:09:08 +0000 (UTC) From: Laurent Vivier To: linux-kernel@vger.kernel.org Cc: Alexander Potapenko , linux-crypto@vger.kernel.org, Dmitriy Vyukov , rusty@rustcorp.com.au, amit@kernel.org, akong@redhat.com, Herbert Xu , "Michael S . Tsirkin" , Matt Mackall , virtualization@lists.linux-foundation.org, Laurent Vivier Subject: [PATCH 1/4] hwrng: virtio - add an internal buffer Date: Wed, 22 Sep 2021 19:09:00 +0200 Message-Id: <20210922170903.577801-2-lvivier@redhat.com> In-Reply-To: <20210922170903.577801-1-lvivier@redhat.com> References: <20210922170903.577801-1-lvivier@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hwrng core uses two buffers that can be mixed in the virtio-rng queue. If the buffer is provided with wait=0 it is enqueued in the virtio-rng queue but unused by the caller. On the next call, core provides another buffer but the first one is filled instead and the new one queued. And the caller reads the data from the new one that is not updated, and the data in the first one are lost. To avoid this mix, virtio-rng needs to use its own unique internal buffer at a cost of a data copy to the caller buffer. Signed-off-by: Laurent Vivier --- drivers/char/hw_random/virtio-rng.c | 43 ++++++++++++++++++++++------- 1 file changed, 33 insertions(+), 10 deletions(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index a90001e02bf7..208c547dcac1 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -18,13 +18,20 @@ static DEFINE_IDA(rng_index_ida); struct virtrng_info { struct hwrng hwrng; struct virtqueue *vq; - struct completion have_data; char name[25]; - unsigned int data_avail; int index; bool busy; bool hwrng_register_done; bool hwrng_removed; + /* data transfer */ + struct completion have_data; + unsigned int data_avail; + /* minimal size returned by rng_buffer_size() */ +#if SMP_CACHE_BYTES < 32 + u8 data[32]; +#else + u8 data[SMP_CACHE_BYTES]; +#endif }; static void random_recv_done(struct virtqueue *vq) @@ -39,14 +46,14 @@ static void random_recv_done(struct virtqueue *vq) } /* The host will fill any buffer we give it with sweet, sweet randomness. */ -static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size) +static void register_buffer(struct virtrng_info *vi) { struct scatterlist sg; - sg_init_one(&sg, buf, size); + sg_init_one(&sg, vi->data, sizeof(vi->data)); /* There should always be room for one buffer. */ - virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL); + virtqueue_add_inbuf(vi->vq, &sg, 1, vi->data, GFP_KERNEL); virtqueue_kick(vi->vq); } @@ -55,6 +62,8 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) { int ret; struct virtrng_info *vi = (struct virtrng_info *)rng->priv; + unsigned int chunk; + size_t read; if (vi->hwrng_removed) return -ENODEV; @@ -62,19 +71,33 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) if (!vi->busy) { vi->busy = true; reinit_completion(&vi->have_data); - register_buffer(vi, buf, size); + register_buffer(vi); } if (!wait) return 0; - ret = wait_for_completion_killable(&vi->have_data); - if (ret < 0) - return ret; + read = 0; + while (size != 0) { + ret = wait_for_completion_killable(&vi->have_data); + if (ret < 0) + return ret; + + chunk = min_t(unsigned int, size, vi->data_avail); + memcpy(buf + read, vi->data, chunk); + read += chunk; + size -= chunk; + vi->data_avail = 0; + + if (size != 0) { + reinit_completion(&vi->have_data); + register_buffer(vi); + } + } vi->busy = false; - return vi->data_avail; + return read; } static void virtio_cleanup(struct hwrng *rng) -- 2.31.1