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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 B4A59C3A5A2 for ; Fri, 20 Sep 2019 21:25:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8EFDA20820 for ; Fri, 20 Sep 2019 21:25:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393913AbfITVZY (ORCPT ); Fri, 20 Sep 2019 17:25:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46018 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2393813AbfITVZR (ORCPT ); Fri, 20 Sep 2019 17:25:17 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B706518CB8F9; Fri, 20 Sep 2019 21:25:16 +0000 (UTC) Received: from mail (ovpn-120-159.rdu2.redhat.com [10.10.120.159]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DE203600C6; Fri, 20 Sep 2019 21:25:13 +0000 (UTC) From: Andrea Arcangeli To: Paolo Bonzini Cc: Vitaly Kuznetsov , "Dr. David Alan Gilbert" , Marcelo Tosatti , Peter Xu , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 16/17] KVM: retpolines: x86: eliminate retpoline from svm.c exit handlers Date: Fri, 20 Sep 2019 17:25:08 -0400 Message-Id: <20190920212509.2578-17-aarcange@redhat.com> In-Reply-To: <20190920212509.2578-1-aarcange@redhat.com> References: <20190920212509.2578-1-aarcange@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.63]); Fri, 20 Sep 2019 21:25:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It's enough to check the exit value and issue a direct call to avoid the retpoline for all the common vmexit reasons. After this commit is applied, here the most common retpolines executed under a high resolution timer workload in the guest on a SVM host: [..] @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 ktime_get_update_offsets_now+70 hrtimer_interrupt+131 smp_apic_timer_interrupt+106 apic_timer_interrupt+15 start_sw_timer+359 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 1940 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_r12+33 force_qs_rnp+217 rcu_gp_kthread+1270 kthread+268 ret_from_fork+34 ]: 4644 @[]: 25095 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 lapic_next_event+28 clockevents_program_event+148 hrtimer_start_range_ns+528 start_sw_timer+356 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 41474 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 clockevents_program_event+148 hrtimer_start_range_ns+528 start_sw_timer+356 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 41474 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 ktime_get+58 clockevents_program_event+84 hrtimer_start_range_ns+528 start_sw_timer+356 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 41887 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 lapic_next_event+28 clockevents_program_event+148 hrtimer_try_to_cancel+168 hrtimer_cancel+21 kvm_set_lapic_tscdeadline_msr+43 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 42723 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 clockevents_program_event+148 hrtimer_try_to_cancel+168 hrtimer_cancel+21 kvm_set_lapic_tscdeadline_msr+43 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 42766 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 ktime_get+58 clockevents_program_event+84 hrtimer_try_to_cancel+168 hrtimer_cancel+21 kvm_set_lapic_tscdeadline_msr+43 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 42848 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 ktime_get+58 start_sw_timer+279 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 499845 @total: 1780243 SVM has no TSC based programmable preemption timer so it is invoking ktime_get() frequently. Signed-off-by: Andrea Arcangeli --- arch/x86/kvm/svm.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index ca9fd1762519..7324243b0a82 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -4991,6 +4991,20 @@ static int handle_exit(struct kvm_vcpu *vcpu) return 0; } +#ifdef CONFIG_RETPOLINE + if (exit_code == SVM_EXIT_MSR) + return msr_interception(svm); + else if (exit_code == SVM_EXIT_VINTR) + return interrupt_window_interception(svm); + else if (exit_code == SVM_EXIT_INTR) + return intr_interception(svm); + else if (exit_code == SVM_EXIT_HLT) + return halt_interception(svm); + else if (exit_code == SVM_EXIT_NPF) + return npf_interception(svm); + else if (exit_code == SVM_EXIT_CPUID) + return cpuid_interception(svm); +#endif return svm_exit_handlers[exit_code](svm); }