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KVM: VMX: Give the guest ownership of cr0.ts when the fpu is active 

If the guest fpu is loaded, there is nothing interesing about cr0.ts; let
the guest play with it as it will.  This makes context switches between fpu
intensive guest processes faster, as we won't trap the clts and cr0 write
instructions.

[marcelo: fix cr0 read shadow update on fpu deactivation; kills F8 install]

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Avi Kivity 2009-12-30 18:07:40 +02:00 committed by Marcelo Tosatti
parent 02daab21d9
commit edcafe3c5a
1 changed files with 9 additions and 2 deletions
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11
arch/x86/kvm/vmx.c
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@ -803,12 +803,20 @@ static void vmx_fpu_activate(struct kvm_vcpu *vcpu)
if (kvm_read_cr0_bits(vcpu, X86_CR0_TS))
vmcs_set_bits(GUEST_CR0, X86_CR0_TS);
update_exception_bitmap(vcpu);
vcpu->arch.cr0_guest_owned_bits = X86_CR0_TS;
vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits);
}
static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu);
static void vmx_fpu_deactivate(struct kvm_vcpu *vcpu)
{
vmx_decache_cr0_guest_bits(vcpu);
vmcs_set_bits(GUEST_CR0, X86_CR0_TS);
update_exception_bitmap(vcpu);
vcpu->arch.cr0_guest_owned_bits = 0;
vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits);
vmcs_writel(CR0_READ_SHADOW, vcpu->arch.cr0);
}
static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu)
@ -2996,8 +3004,7 @@ static int handle_cr(struct kvm_vcpu *vcpu)
};
break;
case 2: /* clts */
vcpu->arch.cr0 &= ~X86_CR0_TS;
vmcs_writel(CR0_READ_SHADOW, kvm_read_cr0(vcpu));
vmx_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~X86_CR0_TS));
trace_kvm_cr_write(0, kvm_read_cr0(vcpu));
skip_emulated_instruction(vcpu);
return 1;