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KVM: Optimize kvm_read_cr[04]_bits()

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'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 <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Avi Kivity 2010-01-21 15:31:51 +02:00 committed by Marcelo Tosatti
parent f6801dff23
commit 8ae0991276
1 changed files with 9 additions and 2 deletions
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11
arch/x86/kvm/kvm_cache_regs.h
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@ -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;
}