From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 A25F933A9CB; Thu, 23 Jul 2026 06:07:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784786865; cv=none; b=IvzXcmhtOVLiq4ReVRKf5RAVboIgNO1l1i4U7bvHYNVDLpYCgJfIDbjPmjyvCGPbHewc6/hrCkrhLQgJeQhEzCm/doaw10UWgLCNLl5jd1j58Gt1fdhvPHyD6Cma71i4PTRlmYFY3zQjcTEM09GFtowjtdz32Hqz1HRw9SIJi9k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784786865; c=relaxed/simple; bh=eBtgSU5dqb0xlXuI63d7nGqrVxcSMF9a6GJF5JFTcw4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JwPlFlzQkpc5Bn9zC5yzVdVw1MQwr0t/vepnYwqIsF2lO+Pr90sQPpB12HSJvEZtdB4TKB12glYhJD9iPeSVhXUCr6f3TLDxJCBl/boE4gQiNL6NTIOFqaKkmcUiOsvdo2+raBwCh5PncQj3O2ld2lNxewe8ADogn/wezotOW8I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nQJDo3/G; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nQJDo3/G" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B7801F000E9; Thu, 23 Jul 2026 06:07:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784786864; bh=mT6AC/CgA/qw0YljyiJfi5cILiHEuRGtFgy9cZoeLZs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=nQJDo3/GGVYcArLXGhUnDsuEfpq0gI82lnmS+vS/mHZLM3k8v4CcDLl7OOChUtjVC lM/k58TuGnVn7xin4tA1xrOvcWYtmPRMjJ98TH8S6XBYcXrNl7fThJiUHyUrfcYgIG bntUJRlVIRkWWFSJ2wdnKHqYjSCapSJ+E27gIdefmwLT5XhXo7bZD0x77cFBp5hYQn YbsZXsHbaw+a0bZThopXh7Mooe6yGMPeXGEM6YMZQD2PP/EBOxqWD3aX5/CD7Pmudd q1m+MAtz0LUUNmPtO0+wxpEAR3BmmLLUBPwWiO0EyHGeOOUSq1aZ5tTOGnxJaJ7WuZ ZegdoPN1F0ORw== Date: Wed, 22 Jul 2026 23:07:43 -0700 From: Wei Liu To: Hardik Garg Cc: "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Saurabh Sengar , Michael Kelley , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] Drivers: hv: vmbus: add VTL2 redirect connection ID Message-ID: <20260723060743.GI2020652@liuwe-devbox-debian-v2.local> References: <20260717001837.635756-1-hargar@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260717001837.635756-1-hargar@linux.microsoft.com> On Fri, Jul 17, 2026 at 12:18:37AM +0000, Hardik Garg wrote: > VMBus sends CHANNELMSG_INITIATE_CONTACT through a Hyper-V message > connection ID. Older protocol versions use VMBUS_MESSAGE_CONNECTION_ID, > while protocol version 5.0 and newer normally use > VMBUS_MESSAGE_CONNECTION_ID_4. > > For a VTL2 kernel using VMBus protocol 5.0 or newer, the host > may expect INITIATE_CONTACT on either the redirect connection ID or > VMBUS_MESSAGE_CONNECTION_ID_4. There is no capability indication that > identifies which ID is active, so the driver must determine it at runtime. > > During VMBus negotiation, the redirect ID is tried first because it is > used by VTL2 configurations with VMBus redirection enabled. If the > redirect ID is unavailable, the host rejects it synchronously with > HV_STATUS_INVALID_CONNECTION_ID, allowing fallback to the standard ID. > > Return a distinct error for an invalid Initiate Contact connection ID so > this fallback does not mask other post-message failures or > protocol-version rejections. Preserve the existing connection ID > selection for older protocol versions or when running below VTL2. > > Signed-off-by: Hardik Garg Applied. Thanks.