From: Avi Kivity Date: Thu, 21 Jan 2010 13:31:51 +0000 (+0200) Subject: KVM: Optimize kvm_read_cr[04]_bits() X-Git-Tag: v2.6.34-rc1~193^2~47 X-Git-Url: http://pileus.org/git/?a=commitdiff_plain;h=8ae099127668de80e4babba73bb492740ce3a1be;p=~andy%2Flinux KVM: Optimize kvm_read_cr[04]_bits() '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 --- diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h index 6b419a36cbd..cff851cf532 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; }