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 D3ED532142B; Mon, 13 Apr 2026 11:44:28 +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=1776080670; cv=none; b=VSSrZWcmFcMzGF2olLo9rROuTwQUbsA+uXlFu1SN5hY89i2uHGs7AedEix1Svcy7Wfe1fgu867qldGqz1Cr18FgWoQOGopbangU1FmoF/EoazZA14+g8T1o4v9BjOBWBZfS9l4kkn2mn7u+HmcAI+nfOzvd/NF+TXfOe74Tk55M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776080670; c=relaxed/simple; bh=bKva/ejDkQSIYxls0YT/LQV3BV++Uth+I04DP9cgoAo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nBWcAi82OYvbYAzGtRgKYIn+6rSv9H8E57OzSZzn7UiFQlXSfBxe9hN8EIEzHIy6paPfcP3xsBdxSuoz956fZuTIoo+Wp7oieWA1WXHrcUtC86u1pXEEvtDaVtPiqhfevP8kbvoDpYKSTAflih9SXZGCdR8mpcaf0c4QNAOlAd8= 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=GdpGvPY6; 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="GdpGvPY6" Received: from [192.168.0.106] (unknown [49.205.253.198]) by linux.microsoft.com (Postfix) with ESMTPSA id ED2F320B7128; Mon, 13 Apr 2026 04:44:21 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com ED2F320B7128 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1776080668; bh=cGNuEHkArBiNiNVxwIRGSAzaCURMpjmGdsqqc7Hqft0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=GdpGvPY6u6Kxlr3Gwj9vd3P3c+ECIc35+EwWAEp1VNH4UT26kmYkva+RZR3iv/Msg uMIxbkofXzjxjwMRBnOSfMzfdKXz8nqUEP5WL2mOZ0gf2qqY16we/vfeRP9v29dxnY GSqaZM25iXA12FMSgbcU8MrMWBs5cmsQkREpOLoM= Message-ID: <7c6e721e-d8e1-45b5-99a3-a8104c212983@linux.microsoft.com> Date: Mon, 13 Apr 2026 17:14:16 +0530 Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/11] arch: arm64: Export arch_smp_send_reschedule for mshv_vtl module To: Michael Kelley , "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 Cc: Marc Zyngier , Timothy Hayes , Lorenzo Pieralisi , mrigendrachaubey , "ssengar@linux.microsoft.com" , "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" References: <20260316121241.910764-1-namjain@linux.microsoft.com> <20260316121241.910764-2-namjain@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 On 4/1/2026 10:24 PM, Michael Kelley wrote: > From: Naman Jain Sent: Monday, March 16, 2026 5:13 AM >> > > Nit: For the patch "Subject", the most common prefix for the file > arch/arm64/kernel/smp.c is "arm64: smp:". I'd suggest using that > prefix for historical consistency. Acked. Will change in v2. > >> mshv_vtl_main.c calls smp_send_reschedule() which expands to >> arch_smp_send_reschedule(). When CONFIG_MSHV_VTL=m, the module cannot >> access this symbol since it is not exported on arm64. >> >> smp_send_reschedule() is used in mshv_vtl_cancel() to interrupt a vCPU >> thread running on another CPU. When a vCPU is looping in >> mshv_vtl_ioctl_return_to_lower_vtl(), it checks a per-CPU cancel flag >> before each VTL0 entry. Setting cancel=1 alone is not enough if the >> target CPU thread is sleeping - the IPI from smp_send_reschedule() kicks >> the remote CPU out of idle/sleep so it re-checks the cancel flag and >> exits the loop promptly. >> >> Other architectures (riscv, loongarch, powerpc) already export this >> symbol. Add the same EXPORT_SYMBOL_GPL for arm64. This is required >> for adding arm64 support in MSHV_VTL. >> >> Signed-off-by: Naman Jain >> --- >> arch/arm64/kernel/smp.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c >> index 1aa324104afb..26b1a4456ceb 100644 >> --- a/arch/arm64/kernel/smp.c >> +++ b/arch/arm64/kernel/smp.c >> @@ -1152,6 +1152,7 @@ void arch_smp_send_reschedule(int cpu) >> { >> smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE); >> } >> +EXPORT_SYMBOL_GPL(arch_smp_send_reschedule); >> >> #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL >> void arch_send_wakeup_ipi(unsigned int cpu) >> -- >> 2.43.0 >> > > The "Subject" nit notwithstanding, > > Reviewed-by: Michael Kelley Thanks, Naman