[PATCH 21/39] KVM: VMX: Give the guest ownership of cr0.ts when the fpu is active
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From: Avi Kivity on 13 Feb 2010 03:10 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(a)redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti(a)redhat.com> --- arch/x86/kvm/vmx.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index d11be3f..fc1964d 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -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; -- 1.6.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |