From: Avi Kivity Date: Wed, 30 Dec 2009 16:07:40 +0000 (+0200) Subject: KVM: VMX: Give the guest ownership of cr0.ts when the fpu is active X-Git-Tag: v2.6.34-rc1~193^2~84 X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=commitdiff_plain;h=edcafe3c5a06f46407c3f60145a36f269e56ff7f 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 Signed-off-by: Marcelo Tosatti --- 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;