From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5CAA3CD3424 for ; Wed, 6 May 2026 05:11:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=g826hBG5sdvtVoUdo7WR5/F7nLFfVhBDlSe4q/ANC2k=; b=SE5WNatlOOX/CU4/YZJisIiOxi /Bdu3+Gfytym/RwanJWAHWS5kMPB2Jeh5sdmmRZaPb5uEM83wxo040lfoHWbPnvXfkbqjbH66znQV JsrM24Nr5CxLvp4Df2aVv8BAL9TQTKC5InsgpAug5hN9GvxX1f177Pu8w2fSXS6PqHYg+0H0yZJPm DnDBms6aJMdvCH7zBYtB/PT8SvbKl1vfqgGTvJnlm5AYoEX56QKb3u429qWvcLJ+r7NifIX0FDLvL wA8XWqO2frc+2lGV9horsac6d6swvgjBipMBnxNh1jMhLWEnNA3ES1G5Vl9n/g7V+zdzcZew65YFs erGotfHw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wKUXZ-00000000lAi-16LI; Wed, 06 May 2026 05:11:21 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wKUXW-00000000l9U-05D6; Wed, 06 May 2026 05:11:20 +0000 Received: from [10.95.65.64] (unknown [167.220.238.64]) by linux.microsoft.com (Postfix) with ESMTPSA id 6F18920B7168; Tue, 5 May 2026 22:11:05 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 6F18920B7168 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1778044272; bh=g826hBG5sdvtVoUdo7WR5/F7nLFfVhBDlSe4q/ANC2k=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=U3sNDtsK/up9rwRUYjKE71paEXx7G/JFAVmIVF6V2Nv4CAPsofHIjZwC6aP/EYO0s UAYeJhR8zLMUktpca2eDmFAvxr/MMokVL5s4fG8oEfRRsB/j2DV01NlxYriEMaMmvN np2+tbmhsnd8n3DXx9Tl2L4uHKUiU4vBu3yQbhNs= Message-ID: Date: Wed, 6 May 2026 10:41:02 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 07/15] arm64: hyperv: Add support for mshv_vtl_return_call To: Michael Kelley Cc: Marc Zyngier , Timothy Hayes , Lorenzo Pieralisi , Sascha Bischoff , mrigendrachaubey , "linux-hyperv@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-riscv@lists.infradead.org" , "vdso@mailbox.org" , "ssengar@linux.microsoft.com" , "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "x86@kernel.org" , "H . Peter Anvin" , Arnd Bergmann , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti References: <20260423124206.2410879-1-namjain@linux.microsoft.com> <20260423124206.2410879-8-namjain@linux.microsoft.com> <516a4e65-3a4d-4e09-b445-28cb740b5653@linux.microsoft.com> Content-Language: en-US From: Naman Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260505_221118_127291_B2CEBA78 X-CRM114-Status: GOOD ( 19.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 5/4/2026 9:36 PM, Michael Kelley wrote: > From: Naman Jain Sent: Wednesday, April 29, 2026 2:57 AM >> >> On 4/27/2026 11:08 AM, Michael Kelley wrote: >>> From: Naman Jain Sent: Thursday, April 23, 2026 5:42 AM >>>> > > [snip] > >>>> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h >>>> index 08278547b84c..b4d80c9a673a 100644 >>>> --- a/arch/x86/include/asm/mshyperv.h >>>> +++ b/arch/x86/include/asm/mshyperv.h >>>> @@ -286,7 +286,6 @@ struct mshv_vtl_cpu_context { >>>> #ifdef CONFIG_HYPERV_VTL_MODE >>>> void __init hv_vtl_init_platform(void); >>>> int __init hv_vtl_early_init(void); >>>> -void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0); >>>> void mshv_vtl_return_call_init(u64 vtl_return_offset); >>>> void mshv_vtl_return_hypercall(void); >>>> void __mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0); >>>> @@ -294,7 +293,6 @@ int hv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set, bool shared); >>>> #else >>>> static inline void __init hv_vtl_init_platform(void) {} >>>> static inline int __init hv_vtl_early_init(void) { return 0; } >>>> -static inline void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0) {} >>>> static inline void mshv_vtl_return_call_init(u64 vtl_return_offset) {} >>>> static inline void mshv_vtl_return_hypercall(void) {} >>>> static inline void __mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0) {} >>>> diff --git a/drivers/hv/mshv_vtl.h b/drivers/hv/mshv_vtl.h >>>> index a6eea52f7aa2..103f07371f3f 100644 >>>> --- a/drivers/hv/mshv_vtl.h >>>> +++ b/drivers/hv/mshv_vtl.h >>>> @@ -22,4 +22,7 @@ struct mshv_vtl_run { >>>> char vtl_ret_actions[MSHV_MAX_RUN_MSG_SIZE]; >>>> }; >>>> >>>> +static_assert(sizeof(struct mshv_vtl_cpu_context) <= 1024, >>>> + "struct mshv_vtl_cpu_context exceeds reserved space in struct mshv_vtl_run"); >>>> + >>>> #endif /* _MSHV_VTL_H */ >>>> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h >>>> index db183c8cfb95..8cdf2a9fbdfb 100644 >>>> --- a/include/asm-generic/mshyperv.h >>>> +++ b/include/asm-generic/mshyperv.h >>>> @@ -396,8 +396,10 @@ static inline int hv_deposit_memory(u64 partition_id, u64 status) >>>> >>>> #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE) >>>> u8 __init get_vtl(void); >>>> +void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0); >>>> #else >>>> static inline u8 get_vtl(void) { return 0; } >>>> +static inline void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0) {} >>> >>> Is this stub needed? Maybe I missed something, but it looks to me like none >>> of the code that calls this gets built unless CONFIG_HYPERV_VTL_MODE is set. >>> See further comments about stubs in Patch 8 of this series. >>> >> >> Config dependencies would handle such cases, and this is not required. I >> saw similar stubs added in the code, so I thought this is a norm that >> should be followed, and not rely on config dependencies. >> I can remove it. >> > > Others might disagree with me, but I don't think it's the norm to add > stubs when they aren't truly needed. As you can see from some of my > other comments, I look for ways to eliminate stubs. Stubs are indicative > of a boundary between separately built components, and I generally > try to minimize the surface area of such boundaries. A large surface area > often means that the overall design could be improved by re-thinking > which code goes with which component. > > Michael I agree. I'll remove these in next version. Thanks, Naman