From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: [PATCH 7/8] KVM: Optimize kvm_read_cr[04]_bits() Date: Thu, 21 Jan 2010 15:31:51 +0200 Message-ID: <1264080712-3981-8-git-send-email-avi@redhat.com> References: <1264080712-3981-1-git-send-email-avi@redhat.com> Cc: kvm@vger.kernel.org To: Marcelo Tosatti Return-path: Received: from mx1.redhat.com ([209.132.183.28]:35258 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752388Ab0AUNbz (ORCPT ); Thu, 21 Jan 2010 08:31:55 -0500 Received: from int-mx05.intmail.prod.int.phx2.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.18]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o0LDVtkw029913 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 21 Jan 2010 08:31:55 -0500 In-Reply-To: <1264080712-3981-1-git-send-email-avi@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: '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 --- arch/x86/kvm/kvm_cache_regs.h | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h index 6b419a3..5a109c6 100644 --- a/arch/x86/kvm/kvm_cache_regs.h +++ b/arch/x86/kvm/kvm_cache_regs.h @@ -1,6 +1,9 @@ #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_PGE + static inline unsigned long kvm_register_read(struct kvm_vcpu *vcpu, enum kvm_reg reg) { @@ -40,7 +43,8 @@ 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 +56,8 @@ 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