From 1c11e713576edf33b95669be9c2dc0ff1e0c90d3 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 3 May 2010 16:05:44 +0300 Subject: [PATCH] KVM: VMX: Avoid writing HOST_CR0 every entry 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 --- arch/x86/kvm/vmx.c | 9 +++------ arch/x86/kvm/x86.c | 2 +- 2 files changed, 4 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 6425207..5989317 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -812,6 +812,8 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx) wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base); } #endif + if (current_thread_info()->status & TS_USEDFPU) + clts(); } static void vmx_load_host_state(struct vcpu_vmx *vmx) @@ -2507,7 +2509,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx) vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, !!bypass_guest_pf); vmcs_write32(CR3_TARGET_COUNT, 0); /* 22.2.1 */ - vmcs_writel(HOST_CR0, read_cr0()); /* 22.2.3 */ + vmcs_writel(HOST_CR0, read_cr0() | X86_CR0_TS); /* 22.2.3 */ vmcs_writel(HOST_CR4, read_cr4()); /* 22.2.3, 22.2.5 */ vmcs_writel(HOST_CR3, read_cr3()); /* 22.2.3 FIXME: shadow tables */ @@ -3859,11 +3861,6 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) vmx_set_interrupt_shadow(vcpu, 0); - /* - * Loading guest fpu may have cleared host cr0.ts - */ - vmcs_writel(HOST_CR0, read_cr0()); - asm( /* Store host registers */ "push %%"R"dx; push %%"R"bp;" diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1b270fd..801afc6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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) -- 2.7.4