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KVM: VMX: Avoid writing HOST_CR0 every entry

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cr0.ts may change between entries, so we copy cr0 to HOST_CR0 before each
entry.  That is slow, so instead, set HOST_CR0 to have TS set unconditionally
(which is a safe value), and issue a clts() just before exiting vcpu context
if the task indeed owns the fpu.

Saves ~50 cycles/exit.

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity
2010-05-03 16:05:44 +03:00
parent 08acfa1871
commit 1c11e71357
2 changed files with 4 additions and 7 deletions
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2
arch/x86/kvm/x86.c
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@ -1731,8 +1731,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
kvm_put_guest_fpu(vcpu);
kvm_x86_ops->vcpu_put(vcpu);
kvm_put_guest_fpu(vcpu);
}
static int is_efer_nx(void)