Commit edcafe3c authored by Avi Kivity's avatar Avi Kivity Committed by Marcelo Tosatti
Browse files

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: default avatarAvi Kivity <avi@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 02daab21

arch/x86/kvm/vmx.c

+9 −2
Original line number Diff line number Diff line
@@ -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;

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