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 E21A81E511; Mon, 20 Oct 2025 19:05:20 +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=1760987122; cv=none; b=Qm3mdiKRSma/4ru1EXNlNgPcOz+NTx21V6eiZt2k8a76OI3e/GjRALZj90sojqDB72ZQSIQt1P9oEMa4AL/2ABM2qURDCLNALmYHB5IXDOwDWME2AnlG9aRWh+I0ibAuJ3F34HATbsYMTraoyXw1Ton6m8hODtksN0AAbLHeJFw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760987122; c=relaxed/simple; bh=k/YGnuYi1+oEiyIdu3aiAPuEkSiMIHNC7xXixsFfNow=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=D7abs0PQ6BvwEYq8Aw+C9GGDcz0KjN7xHWY/aoxXXLqVNLwrFeCPyWfogAtWbPXjzTgNGHXqNCka0hGnRaWuMiS+ohdRyl34zr2decOboEScvd4HpY2xyc8xR+fSnweyYtAsqyvulnyez1b4aSOcdZaBaUEgiTgwE/IWfasd/Go= 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=Q9jSzE+I; 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="Q9jSzE+I" Received: from [192.168.0.88] (192-184-212-33.fiber.dynamic.sonic.net [192.184.212.33]) by linux.microsoft.com (Postfix) with ESMTPSA id 9B8B22017241; Mon, 20 Oct 2025 12:05:19 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 9B8B22017241 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1760987120; bh=YkNbQ2JGZwnFnBbhOku9O15cwzbdr1Cd18AUEiHnxNw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Q9jSzE+I9pwLalOPWqCW9h77biMTbAcRidXNCbivrUIXyjHWBKV27AZkQqr4G2fM9 wXn2IH/sRIzzh65NGo4Sfu1s1jci5OTA07wgJPzGmPF4SeK7JUEdqEHYzitOn99Sb3 Z3fRZJYavWBJx2gvBv2JtFd8IRfkIvc4Amypih5w= Message-ID: <4a4fa302-18fa-ba01-ec06-d4bf0cc84032@linux.microsoft.com> Date: Mon, 20 Oct 2025 12:05:19 -0700 Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Re: [PATCH v3 0/6] Hyper-V: Implement hypervisor core collection Content-Language: en-US To: Michael Kelley , Wei Liu Cc: "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "kys@microsoft.com" , "haiyangz@microsoft.com" , "decui@microsoft.com" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "arnd@arndb.de" References: <20251006224208.1060990-1-mrathor@linux.microsoft.com> <20251017223300.GB632885@liuwe-devbox-debian-v2.local> <20251017225732.GC632885@liuwe-devbox-debian-v2.local> <74e019ac-afc7-3178-0f0a-dc903af5c4ca@linux.microsoft.com> From: Mukesh R In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/17/25 19:54, Michael Kelley wrote: > From: Mukesh R Sent: Friday, October 17, 2025 4:58 PM >> >> On 10/17/25 15:57, Wei Liu wrote: >>> On Fri, Oct 17, 2025 at 10:33:00PM +0000, Wei Liu wrote: >>>> On Mon, Oct 06, 2025 at 03:42:02PM -0700, Mukesh Rathor wrote: >>>> [...] >>>>> Mukesh Rathor (6): >>>>> x86/hyperv: Rename guest crash shutdown function >>>>> hyperv: Add two new hypercall numbers to guest ABI public header >>>>> hyperv: Add definitions for hypervisor crash dump support >>>>> x86/hyperv: Add trampoline asm code to transition from hypervisor >>>>> x86/hyperv: Implement hypervisor RAM collection into vmcore >>>>> x86/hyperv: Enable build of hypervisor crashdump collection files >>>>> >>>> >>>> Applied to hyperv-next. Thanks. >>> >>> This breaks i386 build. >>> >>> /work/linux-on-hyperv/linux.git/arch/x86/hyperv/hv_init.c: In function ?hyperv_init?: >>> /work/linux-on-hyperv/linux.git/arch/x86/hyperv/hv_init.c:557:17: error: implicit declaration of function ?hv_root_crash_init? [-Werror=implicit-function-declaration] >>> 557 | hv_root_crash_init(); >>> | ^~~~~~~~~~~~~~~~~~ >>> >>> That's because CONFIG_MSHV_ROOT is only available on x86_64. And the >>> crash feature is guarded by CONFIG_MSHV_ROOT. >>> >>> Applying the following diff fixes the build. >> >> >> Thanks. A bit surprising tho that CONFIG_MSHV_ROOT doesn't have >> hard dependency on x86_64. It should, no? > > CONFIG_MSHV_ROOT *does* have a hard dependency on X86_64. > > But the problem is actually more pervasive than just 32-bit builds. Because > of the hard dependency, 32-bit builds imply CONFIG_MSHV_ROOT=n, which is > the real problem. In arch/x86/include/asm/mshyperv.h the declaration for > hv_root_crash_init() is available only when CONFIG_MSHV_ROOT is defined > (m or y). There's a stub hv_root_crash_init() if CONFIG_MSHV_ROOT is defined > and CONFIG_CRASH_DUMP=n, but not if CONFIG_MSHV_ROOT=n. The solution > is to add a stub when CONFIG_MSHV_ROOT=n, as below: > > diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h > index 76582affefa8..a5b258d268ed 100644 > --- a/arch/x86/include/asm/mshyperv.h > +++ b/arch/x86/include/asm/mshyperv.h > @@ -248,6 +248,8 @@ void hv_crash_asm_end(void); > static inline void hv_root_crash_init(void) {} > #endif /* CONFIG_CRASH_DUMP */ > > +#else /* CONFIG_MSHV_ROOT */ > +static inline void hv_root_crash_init(void) {} > #endif /* CONFIG_MSHV_ROOT */ > > #else /* CONFIG_HYPERV */ > > Annoyingly, this solution duplicates the hv_root_crash_init() stub. So > an alternate approach that changes a few more lines of code is this: > > diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h > index 76582affefa8..1342d55c2545 100644 > --- a/arch/x86/include/asm/mshyperv.h > +++ b/arch/x86/include/asm/mshyperv.h > @@ -237,18 +237,14 @@ static __always_inline u64 hv_raw_get_msr(unsigned int reg) > } > int hv_apicid_to_vp_index(u32 apic_id); > > -#if IS_ENABLED(CONFIG_MSHV_ROOT) > - > -#ifdef CONFIG_CRASH_DUMP > +#if IS_ENABLED(CONFIG_MSHV_ROOT) && IS_ENABLED(CONFIG_CRASH_DUMP) > void hv_root_crash_init(void); > void hv_crash_asm32(void); > void hv_crash_asm64(void); > void hv_crash_asm_end(void); > -#else /* CONFIG_CRASH_DUMP */ > +#else /* CONFIG_MSHV_ROOT && CONFIG_CRASH_DUMP */ > static inline void hv_root_crash_init(void) {} > -#endif /* CONFIG_CRASH_DUMP */ > - > -#endif /* CONFIG_MSHV_ROOT */ > +#endif /* CONFIG_MSHV_ROOT && CONFIG_CRASH_DUMP */ > > #else /* CONFIG_HYPERV */ > static inline void hyperv_init(void) {} > > Michael Thanks. Yeah, either of the above two is ok. The latter does not duplicate, so may be tiny bit better. Wei will pick one and apply directly. Thanks, -Mukesh