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 AC7C71B85D4; Thu, 19 Dec 2024 20:03:03 +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=1734638585; cv=none; b=taYSWbR8OOq6c9bFUXCOGazf1MS6ThZBAEw+7BvlrFWd9CYCOT4ZKR5ZNRXpZ2qGkHxIk8LkuTdsWN1kUgFvuaPsLZjlFeljX/xegeSyMgWXfgvopi8ZEPkeZY4/k2SmpbRC5Hj2HuTQ3ffJsAADjG+427Asnmr7qjqwFUzJ6vA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734638585; c=relaxed/simple; bh=K+lV/qL2lHo5Jh32rSw4pl5/zX/6WI90wZtqwcADYYk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=hQsHtE9DbR+JFTKebAhv4t+Ziml6LAnXk2QXR5sqLKpf9NCzxnPO2S1YHZtAz6kxlflEgZNDhQgqcHLARrwRLoCu/L0JElOolaEEFod1NUJDDenieZb/o6X6kibrVEkUCiziDe4+8zP1ksI1JM2M1ZIT33eIYhuLJ4sVE8mpmc0= 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=LYUc8Ngc; 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="LYUc8Ngc" Received: from [10.137.184.60] (unknown [131.107.160.188]) by linux.microsoft.com (Postfix) with ESMTPSA id 20397203FC95; Thu, 19 Dec 2024 12:03:03 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 20397203FC95 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1734638583; bh=wTemP+0tJoXt52l2fqnV/vu8lhxelsyT0/sGA2YPyJY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=LYUc8Ngcvp9HOPym5ymCNrywRZZJpPwz1YV/JgKsAoCSfNwyk046HqB+GnGiLJc1e SH33yammzmAKndsy7In7D7zRgpXAVHWEgLfBtUJF1Ze7DwimTCEXBQQvtxbr07Q3Q3 /9zgONOycmCWyAH0XlBKB4gtrO5EteyJmbRBMoDU= Message-ID: Date: Thu, 19 Dec 2024 12:03:02 -0800 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 1/2] hyperv: Fix pointer type for the output of the hypercall in get_vtl(void) To: Easwar Hariharan , Nuno Das Neves Cc: hpa@zytor.com, kys@microsoft.com, bp@alien8.de, dave.hansen@linux.intel.com, decui@microsoft.com, haiyangz@microsoft.com, mingo@redhat.com, mhklinux@outlook.com, tglx@linutronix.de, tiala@microsoft.com, wei.liu@kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, apais@microsoft.com, benhill@microsoft.com, ssengar@microsoft.com, sunilmut@microsoft.com, vdso@hexbites.dev References: <20241218205421.319969-1-romank@linux.microsoft.com> <20241218205421.319969-2-romank@linux.microsoft.com> <17f81f98-a7ca-45e0-87be-9f1cfa5c5a95@linux.microsoft.com> <48d3a3e0-8e2f-4eb8-b725-b6eed37c290c@linux.microsoft.com> <85d4f360-3dd8-4a2b-bdbe-b1997321f48e@linux.microsoft.com> Content-Language: en-US From: Roman Kisel In-Reply-To: <85d4f360-3dd8-4a2b-bdbe-b1997321f48e@linux.microsoft.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/19/2024 11:32 AM, Easwar Hariharan wrote: > On 12/19/2024 11:23 AM, Nuno Das Neves wrote: >> On 12/19/2024 11:13 AM, Easwar Hariharan wrote: >>> On 12/19/2024 10:40 AM, Nuno Das Neves wrote: >>>> On 12/18/2024 12:54 PM, Roman Kisel wrote: >>>>> Commit bc905fa8b633 ("hyperv: Switch from hyperv-tlfs.h to hyperv/hvhdk.h") >>>>> changed the type of the output pointer to `struct hv_register_assoc` from >>>>> `struct hv_get_vp_registers_output`. That leads to an incorrect computation, >>>>> and leaves the system broken. >>>>> >>>> My bad! But, lets not use `struct hv_get_registers_output`. Instead, use >>>> `struct hv_register_value`, since that is the more complete definition of a >>>> register value. The output of the get_vp_registers hypercall is just an array >>>> of these values. >>>> >>>> Ideally we remove `struct hv_get_vp_registers_output` at some point, since >>>> it serves the same role as `struct hv_register_value` but in a more limited >>>> capacity. >>>> >>>> Thanks >>>> Nuno >>>> >>> >>> I had much the same conversation with Roman off-list yesterday. >>> >>> The choice is between using hv_get_registers_output which is clearly the >>> output of the GetVpRegisters hypercall by name, albeit limited as you >> >> If it's desirable to have a more 'friendly' naming here, then I'd be okay with: >> ``` >> /* NOTE: Linux helper struct - NOT from Hyper-V code */ >> struct hv_output_get_vp_registers { >> DECLARE_FLEX_ARRAY(struct hv_register_value, values); >> } >> ``` >> Note also the name is prefixed with "hv_output_" to match other hypercall outputs. > > I like the idea of improving our code readability and consistency in > interface naming independently of the hypervisor. That comment should > allow for clarity when new definitions are imported. > Thank you, Easwar and Nuno, I'll use that in v2! >> >>> said, and hv_register_value which is the more complete definition and >>> what the hypervisor actually returns, but does not currently include the >>> arm64 definitions in our copy of hvgdk_mini.h. hv_get_registers_output >>> and hv_register_value overlap in layout for Roman's purposes. >>> >>> FWIW, I'm in favor of adding the arm64 definitions to hv_register_value >>> and using it for this get_vtl() patch. >>> >>> This could be accompanied with migration of hv_get_vpreg128 in arm64/ >>> and removal of struct hv_get_registers_output, or that could be deferred >>> to a later patch. >> >> I'd be happy to submit a followup patch to update the arm64 code to use >> hv_register_value, or a new struct as outlined above. >> >> It is a pretty small change though, it might be easier to just include it in >> this series. >> > > Thank you! I'll leave it you and Roman to decide how you go about that. > > - Easwar -- Thank you, Roman