From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932377AbdBUTOm (ORCPT ); Tue, 21 Feb 2017 14:14:42 -0500 Received: from mail.kernel.org ([198.145.29.136]:52042 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932354AbdBUTOc (ORCPT ); Tue, 21 Feb 2017 14:14:32 -0500 From: Andy Lutomirski To: Paolo Bonzini , X86 ML Cc: kvm list , "linux-kernel@vger.kernel.org" , Borislav Petkov , Thomas Garnier , Jim Mattson , Andy Lutomirski , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Subject: [PATCH v2 2/7] x86/kvm/vmx: Don't fetch the TSS base from the GDT Date: Tue, 21 Feb 2017 11:14:09 -0800 Message-Id: <41f6d679c5620b5d4dd5746876f29085047bd5bf.1487704145.git.luto@kernel.org> X-Mailer: git-send-email 2.9.3 In-Reply-To: References: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The current CPU's TSS base is a foregone conclusion, so there's no need to parse it out of the segment tables. This should save a couple cycles (as STR is surely microcoded and poorly optimized) but, more importantly, it's a cleanup and it means that segment_base() will never be called on 64-bit kernels. Cc: Thomas Garnier Cc: Jim Mattson Cc: Radim Krčmář Cc: Paolo Bonzini Signed-off-by: Andy Lutomirski --- arch/x86/kvm/vmx.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index a236decb81e4..46420aaf1684 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2088,13 +2088,6 @@ static unsigned long segment_base(u16 selector) return v; } -static inline unsigned long kvm_read_tr_base(void) -{ - u16 tr; - asm("str %0" : "=g"(tr)); - return segment_base(tr); -} - static void vmx_save_host_state(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); @@ -2294,10 +2287,11 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) /* * Linux uses per-cpu TSS and GDT, so set these when switching - * processors. + * processors. See 22.2.4. */ - vmcs_writel(HOST_TR_BASE, kvm_read_tr_base()); /* 22.2.4 */ - vmcs_writel(HOST_GDTR_BASE, gdt->address); /* 22.2.4 */ + vmcs_writel(HOST_TR_BASE, + (unsigned long)this_cpu_ptr(&cpu_tss)); + vmcs_writel(HOST_GDTR_BASE, gdt->address); rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp); vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */ -- 2.9.3