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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 989CBC43387 for ; Tue, 15 Jan 2019 17:49:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6568720675 for ; Tue, 15 Jan 2019 17:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388521AbfAORtz (ORCPT ); Tue, 15 Jan 2019 12:49:55 -0500 Received: from mga18.intel.com ([134.134.136.126]:61806 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728025AbfAORty (ORCPT ); Tue, 15 Jan 2019 12:49:54 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Jan 2019 09:49:54 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,481,1539673200"; d="scan'208";a="312042011" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.154]) by fmsmga005.fm.intel.com with ESMTP; 15 Jan 2019 09:49:53 -0800 Date: Tue, 15 Jan 2019 09:49:53 -0800 From: Sean Christopherson To: Qian Cai Cc: Paolo Bonzini , rkrcmar@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kvm: add proper frame pointer logic for vmx Message-ID: <20190115174953.GC21622@linux.intel.com> References: <20190115064459.70513-1-cai@lca.pw> <5109b3c2-cac0-aa19-9cc7-801340afe198@redhat.com> <7d6ae0bc-b7c7-63ea-ae94-4437a29a31b1@lca.pw> <20190115174845.GB21622@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190115174845.GB21622@linux.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 15, 2019 at 09:48:45AM -0800, Sean Christopherson wrote: > On Tue, Jan 15, 2019 at 11:43:20AM -0500, Qian Cai wrote: > > > > > > On 1/15/19 2:13 AM, Paolo Bonzini wrote: > > > Hmm, maybe like this: > > > > > > diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S > > > index bcef2c7e9bc4..33122fa9d4bd 100644 > > > --- a/arch/x86/kvm/vmx/vmenter.S > > > +++ b/arch/x86/kvm/vmx/vmenter.S > > > @@ -26,19 +26,17 @@ ENTRY(vmx_vmenter) > > > ret > > > > > > 2: vmlaunch > > > +3: > > > ret > > > > > > -3: cmpb $0, kvm_rebooting > > > - jne 4f > > > - call kvm_spurious_fault > > > -4: ret > > > - > > > .pushsection .fixup, "ax" > > > -5: jmp 3b > > > +4: cmpb $0, kvm_rebooting > > > + jne 3b > > > + jmp kvm_spurious_fault > > > .popsection > > > > > > - _ASM_EXTABLE(1b, 5b) > > > - _ASM_EXTABLE(2b, 5b) > > > + _ASM_EXTABLE(1b, 4b) > > > + _ASM_EXTABLE(2b, 4b) > > > > > > ENDPROC(vmx_vmenter) > > > > No, that will not work. The problem is in vmx.o where I just sent another patch > > for it. > > > > I can see there are five options to solve it. > > > > 1) always inline vmx_vcpu_run() > > 2) always noinline vmx_vcpu_run() > > 3) add -fdiable-ipa-fnsplit option to Makefile for vmx.o > > 4) let STACK_FRAME_NON_STANDARD support part.* syntax. > > What is ".part." and where does it come from? Searching for information > is futile, the term is too generic. And never mind, my eyes glazed over -fdiable-ipa-fnsplit. > > 5) trim-down vmx_vcpu_run() even more to not causing splitting by GCC. > > > > Option 1) and 2) seems give away the decision for user with > > CONFIG_CC_OPTIMIZE_FOR_(PERFORMANCE/SIZE). > > > > Option 3) prevents other functions there for splitting for optimization. > > > > Option 4) and 5) seems tricky to implement. > > > > I am not more leaning to 3) as only other fuction will miss splitting is > > vmx_segment_access_rights().