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 83DC11A071C; Thu, 19 Dec 2024 19:32:17 +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=1734636738; cv=none; b=rjjioDy4+bKI3SxfxHe+vdZ+rtf+ffgBp+1uC0NqU8yI07VaSlxFI4vzTZTJEpp05RcMrk1zRBZTtaTO7Q3sPd5Q7euixaiSkPsC/3t7VXiv/BZabGt9+Fea61yf/AJMmWCaO9LJM+w9CeFTvkBM3lMVBGa+8tlYvSDLpUJwfM4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734636738; c=relaxed/simple; bh=QH3pEI2RVdYXemu5Gygt99+Tz2VABVkKmZ8iF15/JqE=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=tEzasIl7jSMUnDWA39sioIGlpgCK9xTdb4MyEm+ijmMxualrE+mRnmuTaQkBicwLXDv8/UtYZ8wkULNUexI0PA2uHWpYUN4sHF/3olUMS7zKJMIAIAGu0L9hshWdv+263fFMejZfI/+q4Tny7CI8W5oggYwqUG6wbGd7zLJdVog= 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=b+8wmOJ+; 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="b+8wmOJ+" Received: from [100.65.65.151] (unknown [20.236.11.29]) by linux.microsoft.com (Postfix) with ESMTPSA id 3B4B920ACD87; Thu, 19 Dec 2024 11:32:16 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 3B4B920ACD87 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1734636736; bh=4kdtH5dmWYcgIKZUcuafzR0kHqokI5hoVY1cPbKFuik=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=b+8wmOJ+xs73BM+1HEjIWjxKLGYujJ8yl/v2mtIipqgAW95JOYIwRTZ5ehpjA6dKd LAr0M6s9UuY4wsxFX4paLz1N+JzfF4xtSRcFELWv/JG24OWcvNl69ElHIxvebvvlLN wnM3ZMLE65TIQYNxzkM+DVk+eoHb1DPpDWc9WiTw= Message-ID: <85d4f360-3dd8-4a2b-bdbe-b1997321f48e@linux.microsoft.com> Date: Thu, 19 Dec 2024 11:32:15 -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 Cc: eahariha@linux.microsoft.com, Roman Kisel , 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 Subject: Re: [PATCH 1/2] hyperv: Fix pointer type for the output of the hypercall in get_vtl(void) To: Nuno Das Neves 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> From: Easwar Hariharan Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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. > >> 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