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X-CSE-ConnectionGUID: cuXbM/DUQeCgxZoqPIX0tg== X-CSE-MsgGUID: QFHF/ofzTuCAsICQnU8FLQ== X-IronPort-AV: E=McAfee;i="6700,10204,11400"; a="57190264" X-IronPort-AV: E=Sophos;i="6.15,202,1739865600"; d="scan'208";a="57190264" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Apr 2025 07:18:52 -0700 X-CSE-ConnectionGUID: o7QVdegNRvSJLWEnhVhM6w== X-CSE-MsgGUID: 9FAYZpHpT2OwCe0ucqzqyA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,202,1739865600"; d="scan'208";a="133036043" Received: from jairdeje-mobl1.amr.corp.intel.com (HELO [10.124.221.45]) ([10.124.221.45]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Apr 2025 07:18:51 -0700 Message-ID: Date: Thu, 10 Apr 2025 07:18:49 -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: Christoph Hellwig , "Xin Li (Intel)" 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> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit 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.