From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 033505323; Fri, 14 Sep 2018 14:10:11 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Sep 2018 05:10:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,373,1531810800"; d="scan'208";a="70828222" Received: from fyigit-mobl.ger.corp.intel.com (HELO [10.252.18.151]) ([10.252.18.151]) by fmsmga008.fm.intel.com with ESMTP; 14 Sep 2018 05:10:07 -0700 To: Tiwei Bie , Maxime Coquelin Cc: zhihong.wang@intel.com, dev@dpdk.org, stable@dpdk.org References: <20180904235555.31839-1-tiwei.bie@intel.com> <20180910073637.GA25254@debian> From: Ferruh Yigit Openpgp: preference=signencrypt Message-ID: <576bfb46-f1fc-cf62-97bc-2d5857215160@intel.com> Date: Fri, 14 Sep 2018 13:10:07 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180910073637.GA25254@debian> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-stable] [PATCH] vhost: fix vhost interrupt support X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 14 Sep 2018 12:10:13 -0000 On 9/10/2018 8:36 AM, Tiwei Bie wrote: > Hi Maxime, > > On Mon, Sep 10, 2018 at 09:22:00AM +0200, Maxime Coquelin wrote: >> Hi Tiwei, >> >> On 09/05/2018 01:55 AM, Tiwei Bie wrote: >>> When VIRTIO_RING_F_EVENT_IDX is negotiated, we need to >>> update the avail event to enable the notification. >>> >>> Fixes: 3f8ff12821e4 ("vhost: support interrupt mode") >>> Cc: stable@dpdk.org >>> >>> Signed-off-by: Tiwei Bie >>> --- >>> lib/librte_vhost/Makefile | 1 + >>> lib/librte_vhost/vhost.c | 18 ++++++++++++------ >>> lib/librte_vhost/vhost.h | 2 ++ >>> 3 files changed, 15 insertions(+), 6 deletions(-) >>> >>> diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile >>> index de431fbb7..531cf4832 100644 >>> --- a/lib/librte_vhost/Makefile >>> +++ b/lib/librte_vhost/Makefile >>> @@ -13,6 +13,7 @@ LIBABIVER := 4 >>> CFLAGS += -DALLOW_EXPERIMENTAL_API >>> CFLAGS += $(WERROR_FLAGS) -I$(SRCDIR) -O3 -D_FILE_OFFSET_BITS=64 >>> CFLAGS += -I vhost_user >>> +CFLAGS += -fno-strict-aliasing >> >> I'm not clear why this is needed looking at the code below, >> could you please explain? > > Without this, we will get below build error: > > lib/librte_vhost/vhost.c: In function ‘vhost_enable_notify_split’: > lib/librte_vhost/vhost.h:656:4: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing] > (*(volatile uint16_t*)&(vr)->used->ring[(vr)->size]) > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > lib/librte_vhost/vhost.c:659:4: note: in expansion of macro ‘vhost_avail_event’ > vhost_avail_event(vq) = vq->last_avail_idx; > ^~~~~~~~~~~~~~~~~ > cc1: all warnings being treated as errors > Getting this error with meson build system, since "-fno-strict-aliasing" is not added to meson build file. BUT instead of disabling compiler warning, first element of the "struct vring_used_elem ring[0]" is "uint32_t id;", so it should be accessed as uint32_t. What about following: #define vhost_avail_event(vr) \ - (*(volatile uint16_t*)&(vr)->used->ring[(vr)->size]) + (*(volatile uint32_t*)&(vr)->used->ring[(vr)->size]) And for "vhost_avail_event(vq) = vq->last_avail_idx;", "last_avail_idx" is uint16_t, so assigning from uint16_t to uint32_t should be ok too. If above works for you please send a patch for update also removing "-fno-strict-aliasing", this can be rebased on existing patch. If not works, please at least send a patch to add flag to meson build file Thanks, ferruh >> >>> LDLIBS += -lpthread >>> ifeq ($(CONFIG_RTE_LIBRTE_VHOST_NUMA),y) >>> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c >>> index 3c9be10a0..88b1781d5 100644 >>> --- a/lib/librte_vhost/vhost.c >>> +++ b/lib/librte_vhost/vhost.c >>> @@ -646,12 +646,18 @@ rte_vhost_avail_entries(int vid, uint16_t queue_id) >>> } >>> static inline void >>> -vhost_enable_notify_split(struct vhost_virtqueue *vq, int enable) >>> +vhost_enable_notify_split(struct virtio_net *dev, >>> + struct vhost_virtqueue *vq, int enable) >>> { >>> - if (enable) >>> - vq->used->flags &= ~VRING_USED_F_NO_NOTIFY; >>> - else >>> - vq->used->flags |= VRING_USED_F_NO_NOTIFY; >>> + if (!(dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX))) { >>> + if (enable) >>> + vq->used->flags &= ~VRING_USED_F_NO_NOTIFY; >>> + else >>> + vq->used->flags |= VRING_USED_F_NO_NOTIFY; >>> + } else { >>> + if (enable) >>> + vhost_avail_event(vq) = vq->last_avail_idx; >>> + } >>> } >>> static inline void >>> @@ -689,7 +695,7 @@ rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int enable) >>> if (vq_is_packed(dev)) >>> vhost_enable_notify_packed(dev, vq, enable); >>> else >>> - vhost_enable_notify_split(vq, enable); >>> + vhost_enable_notify_split(dev, vq, enable); >>> return 0; >>> } >>> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h >>> index 760a09c0d..25ffd7614 100644 >>> --- a/lib/librte_vhost/vhost.h >>> +++ b/lib/librte_vhost/vhost.h >>> @@ -648,6 +648,8 @@ vhost_iova_to_vva(struct virtio_net *dev, struct vhost_virtqueue *vq, >>> return __vhost_iova_to_vva(dev, vq, iova, len, perm); >>> } >>> +#define vhost_avail_event(vr) \ >>> + (*(volatile uint16_t*)&(vr)->used->ring[(vr)->size]) >>> #define vhost_used_event(vr) \ >>> (*(volatile uint16_t*)&(vr)->avail->ring[(vr)->size]) >>>