From 2ab455ccceb07945368709ba852e49f4c3119331 Mon Sep 17 00:00:00 2001 From: Anthony Liguori Date: Fri, 27 Apr 2007 09:29:49 +0300 Subject: [PATCH] KVM: VMX: Add lazy FPU support for VT Only save/restore the FPU host state when the guest is actually using the FPU. Signed-off-by: Anthony Liguori Signed-off-by: Avi Kivity --- drivers/kvm/vmx.c | 61 +++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 56 insertions(+), 5 deletions(-) diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c index 09608114e29a..5a2a68dec6bf 100644 --- a/drivers/kvm/vmx.c +++ b/drivers/kvm/vmx.c @@ -101,6 +101,13 @@ static inline int is_page_fault(u32 intr_info) (INTR_TYPE_EXCEPTION | PF_VECTOR | INTR_INFO_VALID_MASK); } +static inline int is_no_device(u32 intr_info) +{ + return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK | + INTR_INFO_VALID_MASK)) == + (INTR_TYPE_EXCEPTION | NM_VECTOR | INTR_INFO_VALID_MASK); +} + static inline int is_external_interrupt(u32 intr_info) { return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK)) @@ -216,6 +223,16 @@ static void vmcs_write64(unsigned long field, u64 value) #endif } +static void vmcs_clear_bits(unsigned long field, u32 mask) +{ + vmcs_writel(field, vmcs_readl(field) & ~mask); +} + +static void vmcs_set_bits(unsigned long field, u32 mask) +{ + vmcs_writel(field, vmcs_readl(field) | mask); +} + /* * Switches to specified vcpu, until a matching vcpu_put(), but assumes * vcpu mutex is already taken. @@ -833,6 +850,11 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) } #endif + if (!(cr0 & CR0_TS_MASK)) { + vcpu->fpu_active = 1; + vmcs_clear_bits(EXCEPTION_BITMAP, CR0_TS_MASK); + } + vmcs_writel(CR0_READ_SHADOW, cr0); vmcs_writel(GUEST_CR0, (cr0 & ~KVM_GUEST_CR0_MASK) | KVM_VM_CR0_ALWAYS_ON); @@ -842,6 +864,12 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) { vmcs_writel(GUEST_CR3, cr3); + + if (!(vcpu->cr0 & CR0_TS_MASK)) { + vcpu->fpu_active = 0; + vmcs_set_bits(GUEST_CR0, CR0_TS_MASK); + vmcs_set_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR); + } } static void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) @@ -1368,6 +1396,15 @@ static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) asm ("int $2"); return 1; } + + if (is_no_device(intr_info)) { + vcpu->fpu_active = 1; + vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR); + if (!(vcpu->cr0 & CR0_TS_MASK)) + vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK); + return 1; + } + error_code = 0; rip = vmcs_readl(GUEST_RIP); if (intr_info & INTR_INFO_DELIEVER_CODE_MASK) @@ -1556,7 +1593,11 @@ static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) break; case 2: /* clts */ vcpu_load_rsp_rip(vcpu); - set_cr0(vcpu, vcpu->cr0 & ~CR0_TS_MASK); + vcpu->fpu_active = 1; + vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR); + vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK); + vcpu->cr0 &= ~CR0_TS_MASK; + vmcs_writel(CR0_READ_SHADOW, vcpu->cr0); skip_emulated_instruction(vcpu); return 1; case 1: /*mov from cr*/ @@ -1806,8 +1847,14 @@ again: if (vcpu->guest_debug.enabled) kvm_guest_debug_pre(vcpu); - fx_save(vcpu->host_fx_image); - fx_restore(vcpu->guest_fx_image); + if (vcpu->fpu_active) { + fx_save(vcpu->host_fx_image); + fx_restore(vcpu->guest_fx_image); + } + /* + * Loading guest fpu may have cleared host cr0.ts + */ + vmcs_writel(HOST_CR0, read_cr0()); #ifdef CONFIG_X86_64 if (is_long_mode(vcpu)) { @@ -1965,8 +2012,11 @@ again: } #endif - fx_save(vcpu->guest_fx_image); - fx_restore(vcpu->host_fx_image); + if (vcpu->fpu_active) { + fx_save(vcpu->guest_fx_image); + fx_restore(vcpu->host_fx_image); + } + vcpu->interrupt_window_open = (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0; asm ("mov %0, %%ds; mov %0, %%es" : : "r"(__USER_DS)); @@ -2078,6 +2128,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu) vmcs_clear(vmcs); vcpu->vmcs = vmcs; vcpu->launched = 0; + vcpu->fpu_active = 1; return 0; -- 2.30.2