From: Naman Jain <namjain@linux.microsoft.com>
To: Hardik Garg <hargar@linux.microsoft.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
Saurabh Sengar <ssengar@linux.microsoft.com>,
Michael Kelley <mhklinux@outlook.com>,
linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] Drivers: hv: vmbus: add VTL2 redirect connection ID
Date: Mon, 20 Jul 2026 21:04:56 +0530 [thread overview]
Message-ID: <b7971bb1-f168-44b0-b314-0ab407cbbd9f@linux.microsoft.com> (raw)
In-Reply-To: <20260717001837.635756-1-hargar@linux.microsoft.com>
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 <hargar@linux.microsoft.com>
> ---
>
Reviewed-by: Naman Jain <namjain@linux.microsoft.com>
next prev parent reply other threads:[~2026-07-20 15:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-17 0:18 [PATCH v2] Drivers: hv: vmbus: add VTL2 redirect connection ID Hardik Garg
2026-07-17 2:58 ` Michael Kelley
2026-07-20 15:34 ` Naman Jain [this message]
2026-07-21 15:11 ` Saurabh Singh Sengar
2026-07-22 13:22 ` Tianyu Lan
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