From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932962Ab0BPKkZ (ORCPT ); Tue, 16 Feb 2010 05:40:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47431 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932807Ab0BPKfk (ORCPT ); Tue, 16 Feb 2010 05:35:40 -0500 From: Avi Kivity To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH 19/38] KVM: Optimize kvm_read_cr[04]_bits() Date: Tue, 16 Feb 2010 12:35:17 +0200 Message-Id: <1266316536-28936-20-git-send-email-avi@redhat.com> In-Reply-To: <1266316536-28936-1-git-send-email-avi@redhat.com> References: <1266316536-28936-1-git-send-email-avi@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 'mask' is always a constant, so we can check whether it includes a bit that might be owned by the guest very cheaply, and avoid the decache call. Saves a few hundred bytes of module text. Signed-off-by: Avi Kivity Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/kvm_cache_regs.h | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h index 6b419a3..cff851c 100644 --- a/arch/x86/kvm/kvm_cache_regs.h +++ b/arch/x86/kvm/kvm_cache_regs.h @@ -1,6 +1,11 @@ #ifndef ASM_KVM_CACHE_REGS_H #define ASM_KVM_CACHE_REGS_H +#define KVM_POSSIBLE_CR0_GUEST_BITS X86_CR0_TS +#define KVM_POSSIBLE_CR4_GUEST_BITS \ + (X86_CR4_PVI | X86_CR4_DE | X86_CR4_PCE | X86_CR4_OSFXSR \ + | X86_CR4_OSXMMEXCPT | X86_CR4_PGE) + static inline unsigned long kvm_register_read(struct kvm_vcpu *vcpu, enum kvm_reg reg) { @@ -40,7 +45,8 @@ static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index) static inline ulong kvm_read_cr0_bits(struct kvm_vcpu *vcpu, ulong mask) { - if (mask & vcpu->arch.cr0_guest_owned_bits) + ulong tmask = mask & KVM_POSSIBLE_CR0_GUEST_BITS; + if (tmask & vcpu->arch.cr0_guest_owned_bits) kvm_x86_ops->decache_cr0_guest_bits(vcpu); return vcpu->arch.cr0 & mask; } @@ -52,7 +58,8 @@ static inline ulong kvm_read_cr0(struct kvm_vcpu *vcpu) static inline ulong kvm_read_cr4_bits(struct kvm_vcpu *vcpu, ulong mask) { - if (mask & vcpu->arch.cr4_guest_owned_bits) + ulong tmask = mask & KVM_POSSIBLE_CR4_GUEST_BITS; + if (tmask & vcpu->arch.cr4_guest_owned_bits) kvm_x86_ops->decache_cr4_guest_bits(vcpu); return vcpu->arch.cr4 & mask; } -- 1.6.5.3