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 5D05F3B27E7; Tue, 6 Oct 2026 10:08:34 +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=1791281315; cv=none; b=eA/4EBfejiZMqo7rMllTiexUuSmkXOH41GvSmWN+Epm2udOOIvL9uNzeh9NiAyl/Vb7/fNnoAAfTppSAL60lNzaUHfmGi+PUH54McCxZ0Oa/B7suR/YWdLKZriPHcWJTzLr3aqPuASjboqxaeHhZRo1II3j4uzoNiAYXXG8uA30= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791281315; c=relaxed/simple; bh=gnp8MSjVsj2xCAhK7jar17DLHCZrDPkcKPJcGmYENxY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RrLc/aAyX9CmU8A1zv5amPcYxFhyCWlibVA6e2tCudZqPDtX/l7r3Aiivo1TXe8AdAz3qiXlG5s9acAXxO8F1II2tGnLxU51Tf3VQ806jMg7CwHD6kVw6vlKW/YsuCwYsUkCJDtu8LzmS7s6bzA8M8bgjO8NrKCWL3sEJ1ySzCU= 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=qvjOFXrC; 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="qvjOFXrC" Received: from [10.95.66.108] (unknown [52.172.102.222]) by linux.microsoft.com (Postfix) with ESMTPSA id 7A7A720B7166; Tue, 6 Oct 2026 03:07:31 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 7A7A720B7166 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1791281257; bh=Gt1lp+Gdyr+I3+ep/fgfelXAWkuyT6J0SUoT/mWxGK4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=qvjOFXrCl2Fm7UpQpdxBBERC1/pwNW9LxDDp3yH1tH7KYtGcXxKtDlsJpfibq4Vxk Bfi9nnVAY5937ciu1VKyQMFEYjye25C0BExY/t+G8WcJcHJSN6M88oNg75ZsdQb1qQ r6E4hq1xVBJAJYQEspNRjH1QwGQ0La7JWOgo7buE= Message-ID: <6c1752b6-d09b-4d64-ac33-ab401df266fd@linux.microsoft.com> Date: Tue, 6 Oct 2026 15:38:23 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 0/2] hyperv: Run VMBus kexec cleanup from syscore shutdown To: Shradha Gupta , Michael Kelley , Wei Liu , Catalin Marinas , Baoquan He Cc: Will Deacon , "K . Y . Srinivasan" , Haiyang Zhang , Dexuan Cui , Long Li , Andrew Morton , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Arnd Bergmann , linux-hyperv@vger.kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org References: <20261001132128.1703511-1-shradhagupta@linux.microsoft.com> Content-Language: en-US From: Naman Jain In-Reply-To: <20261001132128.1703511-1-shradhagupta@linux.microsoft.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/1/2026 6:51 PM, Shradha Gupta wrote: > Kexec reboot fails on ARM64 Hyper-V guests because the VMBus > connection and SynIC CPU hotplug state are not torn down before the > secondary CPUs are stopped. The kexec kernel consequently starts with > the previous kernel's VMBus state still active. > > The previous version added an ARM64-specific syscore shutdown > implementation. This version follows Michael Kelley's review and moves > the cleanup into the existing architecture-independent VMBus syscore > operations. This removes the separate x86 handler dispatch and gives > x86 and ARM64 the same ordering: > > device_shutdown() > syscore_shutdown() > VMBus UNLOAD and SynIC CPU hotplug teardown > machine_shutdown() > > On x86, VMBus teardown now runs before hv_stimer_global_cleanup(). > This ordering is safe after commit be0cfab740e5 ("clocksource: hyper-v: > Remove support for stimer interrupts in message mode") removed the > VMBus dependency from synthetic timer handling. > > Patch 1 adds a read-only helper that reports whether a kexec reboot is > in progress. The helper is exported because HYPERV_VMBUS is tristate > and the common syscore callback must also link when VMBus is a module. > Patch 2 moves the cleanup into the common callback and removes the > obsolete architecture-specific setup/remove interface. > > For stable kernels that still support message-mode stimers, an > ARM64-specific backport will be needed to preserve the existing x86 > ordering. > > Changes in v3: > - Use the existing common VMBus syscore operations on all > architectures, as suggested by Michael. > - Remove the x86 handler pointer and the weak setup/remove interface. > - Add an exported read-only helper for modular VMBus builds. > - Correct the Fixes tag to the commit that enabled Hyper-V on ARM64. > > Changes in v2: > - Use syscore shutdown instead of an ARM64 machine_shutdown() hook, as > suggested by Catalin. > > Shradha Gupta (2): > kexec: Add helper to report an active kexec reboot > Drivers: hv: Run VMBus kexec cleanup from syscore shutdown > > arch/x86/kernel/cpu/mshyperv.c | 17 +---------------- > drivers/hv/hv_common.c | 10 ---------- > drivers/hv/vmbus_drv.c | 22 ++++++++++++++-------- > include/asm-generic/mshyperv.h | 2 -- > include/linux/kexec.h | 2 ++ > kernel/kexec_core.c | 7 +++++++ > 6 files changed, 24 insertions(+), 36 deletions(-) > > > base-commit: be0cfab740e58b70047ef6e7e3d578f00ed5d258 Since the approach changed in this version and previously reviewed-by tags were not applicable, sharing them again for the series. Reviewed-by: Naman Jain Regards, Naman