From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E1B691096F; Fri, 11 Apr 2025 16:17:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744388264; cv=none; b=noGIsue0T8Yhe8sgXwqIJchtS/pDtuxvl2BqEkqNGcye/simVZ6w6n8E2YCQXYrpikZJ+R35CX7ew88Oz0R9n6JRgGdwa/5PhY7iDTVi4EHUPvKZCTlRAlRhp/2jPlu6IRPHsbnLbFVrCKHf2IjRyexvPzp5Tf8K7OeA2RfUWD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744388264; c=relaxed/simple; bh=ofn7XasYbL6HV6msHMWQ5/n1EDKYsh7K8ld9N4uLdI4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bWHtig6NQ5BczjMWyTGQQuMiumOF9DOTg4nbW5hBSLdn5Ke5Ci5sQAzjsYtaD7D1zKYMLUsbx0QJZxSQDOpOr9OpUWi4jfCVj0zD2U+KC2u4OMm9utQC38G8gMkLfl3t9RNBIYoCp/6Do+s8+1Yb5nc6NoIb5qKxkfTdBPQq1W8= ARC-Authentication-Results:i=1; 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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=hFr0NUvDO0KxnqHVd5tvh9wlEpPLoXj5+Fk6VRp98Oufm46awXFQUGmxV/fTfgMrx GzKsVKrNaQ4GKWIS49y82WqrPyQZdWjzvwEUzzMeF18SIrRIxD7pRirRv3yvheYKEE qAUhHwHGouynqmSNswzUfCwMzXOIh7q1kaCMyUTDJJTa9yd+hAnd6McuU1bc7BfoPc eQneZepAltsYPsjYuY/TJFnv79plc+f+g/zZNkbo0sIfICoW48HmlTCXZhE1q5HFkw m3fln8o2KWtLCxcgstTZDEqws5rEYsoFSuQi9X+5Dtycrj6nld6wkvj3/RmP2kBtIf z2Gw0Sp7D9H9w== Message-ID: Date: Fri, 11 Apr 2025 09:16:33 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 04/19] x86/cea: Export per CPU array 'cea_exception_stacks' for KVM to use To: Dave Hansen , Christoph Hellwig Cc: pbonzini@redhat.com, seanjc@google.com, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, andrew.cooper3@citrix.com, luto@kernel.org, peterz@infradead.org, chao.gao@intel.com, xin3.li@intel.com References: <20250328171205.2029296-1-xin@zytor.com> <20250328171205.2029296-5-xin@zytor.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/10/2025 7:18 AM, Dave Hansen wrote: > On 4/10/25 01:53, Christoph Hellwig wrote: >> On Fri, Mar 28, 2025 at 10:11:50AM -0700, Xin Li (Intel) wrote: >>> The per CPU array 'cea_exception_stacks' points to per CPU stacks >>> +/* >>> + * FRED introduced new fields in the host-state area of the VMCS for >>> + * stack levels 1->3 (HOST_IA32_FRED_RSP[123]), each respectively >>> + * corresponding to per CPU stacks for #DB, NMI and #DF. KVM must >>> + * populate these each time a vCPU is loaded onto a CPU. >>> + */ >>> +EXPORT_PER_CPU_SYMBOL(cea_exception_stacks); >> Exporting data vs accessors for it is usually a bad idea. Doing a >> non-_GPl for such a very low level data struture is even worse. > > Big ack on this. > > I don't even see a single caller of __this_cpu_ist_top_va() that's > remotely performance sensitive or that needs to be inline. > > Just make the __this_cpu_ist_top/bottom_va() macros into real functions > and export __this_cpu_ist_top_va(). It's going to be a pretty tiny > function but I think that's tolerable. > Right, that does make sense to me.