From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E32D238655D; Mon, 20 Jul 2026 15:35:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784561706; cv=none; b=IYDlU+gPEukRrdcx5O4Ga9o9+AS3sMSQeEZ6ArC2XjAWSMj/QO1ib8jkkZN7BKA9js+GWO9eN+XlEIhCRbi0A5OYhFVbdXPKfAzsTyot58AeTxC7HFHgusMHDW4SmA3wUFJvsaFXHiw+el5F/EcRmiGtVSB6s9Ouixakx/WeLuQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784561706; c=relaxed/simple; bh=+T2sEFPE7rajc5fFUOqc2Dj30tK0NkXWP8OCzB+8pDA=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=lVdSOiZ6UJ9mPtY8LLkIqsZmcRxPqTN9J7hw77r7mEXswjKe7UxOPs71F+Mr+WpzJvrZBo13H+X6wxWqK2ZQfjd5r+Cin1TShg6BXovHn9QO7QQ3vpydDFDcyk2skZ4dwBegP4k5/6az9IhDw4a4ZMwbVrTJ/4V4jC1qDWIet+k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=oMVGNHfh; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="oMVGNHfh" Received: from [192.168.0.105] (unknown [4.194.122.170]) by linux.microsoft.com (Postfix) with ESMTPSA id 13C0020B7169; Mon, 20 Jul 2026 08:34:46 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 13C0020B7169 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1784561689; bh=pZ+9ojnYusCUcERhkOrfi+2aUjIQwCqu+PtVtnijj10=; h=Date:Subject:To:References:From:In-Reply-To:From; b=oMVGNHfhCj1t1t4VbyPuEAuvI7Hnm+fxI0Q0hNNV2UbSt+AK2KVhBtgpfSMzEyIXg FC8MpiDK6XS1HbxFpHUJU5QNl2F+WMr+VRqDERvtrvxA16sKd+ablQ6+jzrTUZcH+z gQP+HyT48QMzSODz/aQizQ+cIGyHqjc6cQXgO5Do= Message-ID: Date: Mon, 20 Jul 2026 21:04:56 +0530 Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] Drivers: hv: vmbus: add VTL2 redirect connection ID To: Hardik Garg , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Saurabh Sengar , Michael Kelley , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260717001837.635756-1-hargar@linux.microsoft.com> Content-Language: en-US From: Naman Jain In-Reply-To: <20260717001837.635756-1-hargar@linux.microsoft.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/17/2026 5:48 AM, 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 > --- > Reviewed-by: Naman Jain