From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2AAFF24418D for ; Wed, 28 May 2025 06:43:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748414633; cv=none; b=gYPOFa0Krw2Gb9AgGo+v0WQl4TDbstlozb9QdbPwre0u11n0PbMVROYwgBcdKgTuUX2fr8r/iuysn6PWasN9SmSE059ttm92ZZO11j8jLz7a81U36wh9aNKnKlNrLjPuFMrTnJlN5wfxdzl8MXlim9Uu/+SMc3NS97SWJLsW5gc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748414633; c=relaxed/simple; bh=QE9b1joO3P53vlD1O5kxYhXU8+LWJX93eEfFeNpQ0XE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nYTUDH31uOL6TcQCDikpaSJ4lNuTARRwQ56xMKv58U6F4qhLuP7GabpwzDgUIlPr2olsZhNGovfDsB3EEB8FhzgFsfNjgptrXTXgWpsrHgAHUW4blAQAMvzHRAuiriD/IfLGFXtyRHXJjCnZ+lqWLa1kSVg77NDMuxGm9tbjg2s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=W0TywvJ+; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="W0TywvJ+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1748414631; 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=+iZWJRbVoWfyzg7P4mKc5R5mrCEqCCYAsV0aepJYIeM=; b=W0TywvJ+lkiIW0jp4vrc02fn/T7ryJVri4clxhDK0KFzW2jkw6CknTVBIwPmcTXnkEBoJg 9UdWsLxjzxO9g7jVfTw6E2B4qvsMktQUAWYJGJafeQ05OG2dVOG/4XxrRTGucUzqBtZo6w RJQFw1Za5eZlDzOOZ2wd5NFzrSR5JtI= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-529-S_FDkzDKMLGg3BuDeSuiLA-1; Wed, 28 May 2025 02:43:47 -0400 X-MC-Unique: S_FDkzDKMLGg3BuDeSuiLA-1 X-Mimecast-MFC-AGG-ID: S_FDkzDKMLGg3BuDeSuiLA_1748414626 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D602D1954207; Wed, 28 May 2025 06:43:46 +0000 (UTC) Received: from localhost.localdomain (unknown [10.72.112.248]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B0CAC1956095; Wed, 28 May 2025 06:43:43 +0000 (UTC) From: Jason Wang To: mst@redhat.com, jasowang@redhat.com Cc: xuanzhuo@linux.alibaba.com, eperezma@redhat.com, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH V2 16/19] virtio_ring: factor out core logic for updating last_used_idx Date: Wed, 28 May 2025 14:42:31 +0800 Message-ID: <20250528064234.12228-17-jasowang@redhat.com> In-Reply-To: <20250528064234.12228-1-jasowang@redhat.com> References: <20250528064234.12228-1-jasowang@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Factor out the core logic for updating last_used_idx to be reused by the packed in order implementation. Reviewed-by: Xuan Zhuo Signed-off-by: Jason Wang --- drivers/virtio/virtio_ring.c | 43 +++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 18 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 1bdd332d515e..e8e0d1204f52 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -1757,6 +1757,30 @@ static bool more_used_packed(const struct vring_virtqueue *vq) return virtqueue_poll_packed(vq, READ_ONCE(vq->last_used_idx)); } +static void update_last_used_idx_packed(struct vring_virtqueue *vq, + u16 id, u16 last_used, + u16 used_wrap_counter) +{ + last_used += vq->packed.desc_state[id].num; + if (unlikely(last_used >= vq->packed.vring.num)) { + last_used -= vq->packed.vring.num; + used_wrap_counter ^= 1; + } + + last_used = (last_used | (used_wrap_counter << VRING_PACKED_EVENT_F_WRAP_CTR)); + WRITE_ONCE(vq->last_used_idx, last_used); + + /* + * If we expect an interrupt for the next entry, tell host + * by writing event index and flush out the write before + * the read in the next get_buf call. + */ + if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DESC) + virtio_store_mb(vq->weak_barriers, + &vq->packed.vring.driver->off_wrap, + cpu_to_le16(vq->last_used_idx)); +} + static void *virtqueue_get_buf_ctx_packed(struct vring_virtqueue *vq, unsigned int *len, void **ctx) @@ -1800,24 +1824,7 @@ static void *virtqueue_get_buf_ctx_packed(struct vring_virtqueue *vq, ret = vq->packed.desc_state[id].data; detach_buf_packed(vq, id, ctx); - last_used += vq->packed.desc_state[id].num; - if (unlikely(last_used >= vq->packed.vring.num)) { - last_used -= vq->packed.vring.num; - used_wrap_counter ^= 1; - } - - last_used = (last_used | (used_wrap_counter << VRING_PACKED_EVENT_F_WRAP_CTR)); - WRITE_ONCE(vq->last_used_idx, last_used); - - /* - * If we expect an interrupt for the next entry, tell host - * by writing event index and flush out the write before - * the read in the next get_buf call. - */ - if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DESC) - virtio_store_mb(vq->weak_barriers, - &vq->packed.vring.driver->off_wrap, - cpu_to_le16(vq->last_used_idx)); + update_last_used_idx_packed(vq, id, last_used, used_wrap_counter); LAST_ADD_TIME_INVALID(vq); -- 2.31.1