KVM: VMX: Use shadow TPR/cr8 for 64-bits guests
This patch enables TPR shadow of VMX on CR8 access. 64bit Windows using
CR8 access TPR frequently. The TPR shadow can improve the performance of
access TPR by not causing vmexit.
Signed-off-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Yaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: Qing He <qing.he@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 6c371ea..5c2c6e7 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -170,6 +170,16 @@
== (INTR_TYPE_EXT_INTR | INTR_INFO_VALID_MASK);
}
+static inline int cpu_has_vmx_tpr_shadow(void)
+{
+ return (vmcs_config.cpu_based_exec_ctrl & CPU_BASED_TPR_SHADOW);
+}
+
+static inline int vm_need_tpr_shadow(struct kvm *kvm)
+{
+ return ((cpu_has_vmx_tpr_shadow()) && (irqchip_in_kernel(kvm)));
+}
+
static int __find_msr_index(struct vcpu_vmx *vmx, u32 msr)
{
int i;
@@ -888,10 +898,19 @@
CPU_BASED_USE_IO_BITMAPS |
CPU_BASED_MOV_DR_EXITING |
CPU_BASED_USE_TSC_OFFSETING;
+#ifdef CONFIG_X86_64
+ opt = CPU_BASED_TPR_SHADOW;
+#else
opt = 0;
+#endif
if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_PROCBASED_CTLS,
&_cpu_based_exec_control) < 0)
return -EIO;
+#ifdef CONFIG_X86_64
+ if ((_cpu_based_exec_control & CPU_BASED_TPR_SHADOW))
+ _cpu_based_exec_control &= ~CPU_BASED_CR8_LOAD_EXITING &
+ ~CPU_BASED_CR8_STORE_EXITING;
+#endif
min = 0;
#ifdef CONFIG_X86_64
@@ -1384,6 +1403,7 @@
int ret = 0;
unsigned long kvm_vmx_return;
u64 msr;
+ u32 exec_control;
if (!init_rmode_tss(vmx->vcpu.kvm)) {
ret = -ENOMEM;
@@ -1459,8 +1479,16 @@
/* Control */
vmcs_write32(PIN_BASED_VM_EXEC_CONTROL,
vmcs_config.pin_based_exec_ctrl);
- vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
- vmcs_config.cpu_based_exec_ctrl);
+
+ exec_control = vmcs_config.cpu_based_exec_ctrl;
+ if (!vm_need_tpr_shadow(vmx->vcpu.kvm)) {
+ exec_control &= ~CPU_BASED_TPR_SHADOW;
+#ifdef CONFIG_X86_64
+ exec_control |= CPU_BASED_CR8_STORE_EXITING |
+ CPU_BASED_CR8_LOAD_EXITING;
+#endif
+ }
+ vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, exec_control);
vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, 0);
vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, 0);
@@ -1532,8 +1560,11 @@
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0); /* 22.2.1 */
#ifdef CONFIG_X86_64
- vmcs_writel(VIRTUAL_APIC_PAGE_ADDR, 0);
- vmcs_writel(TPR_THRESHOLD, 0);
+ vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, 0);
+ if (vm_need_tpr_shadow(vmx->vcpu.kvm))
+ vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,
+ page_to_phys(vmx->vcpu.apic->regs_page));
+ vmcs_write32(TPR_THRESHOLD, 0);
#endif
vmcs_writel(CR0_GUEST_HOST_MASK, ~0UL);
@@ -1969,6 +2000,12 @@
return 1;
}
+static int handle_tpr_below_threshold(struct kvm_vcpu *vcpu,
+ struct kvm_run *kvm_run)
+{
+ return 1;
+}
+
static void post_kvm_run_save(struct kvm_vcpu *vcpu,
struct kvm_run *kvm_run)
{
@@ -2036,6 +2073,7 @@
[EXIT_REASON_PENDING_INTERRUPT] = handle_interrupt_window,
[EXIT_REASON_HLT] = handle_halt,
[EXIT_REASON_VMCALL] = handle_vmcall,
+ [EXIT_REASON_TPR_BELOW_THRESHOLD] = handle_tpr_below_threshold
};
static const int kvm_vmx_max_exit_handlers =
@@ -2083,6 +2121,23 @@
{
}
+static void update_tpr_threshold(struct kvm_vcpu *vcpu)
+{
+ int max_irr, tpr;
+
+ if (!vm_need_tpr_shadow(vcpu->kvm))
+ return;
+
+ if (!kvm_lapic_enabled(vcpu) ||
+ ((max_irr = kvm_lapic_find_highest_irr(vcpu)) == -1)) {
+ vmcs_write32(TPR_THRESHOLD, 0);
+ return;
+ }
+
+ tpr = (kvm_lapic_get_cr8(vcpu) & 0x0f) << 4;
+ vmcs_write32(TPR_THRESHOLD, (max_irr > tpr) ? tpr >> 4 : max_irr >> 4);
+}
+
static void enable_irq_window(struct kvm_vcpu *vcpu)
{
u32 cpu_based_vm_exec_control;
@@ -2097,6 +2152,8 @@
u32 idtv_info_field, intr_info_field;
int has_ext_irq, interrupt_window_open;
+ update_tpr_threshold(vcpu);
+
has_ext_irq = kvm_cpu_has_interrupt(vcpu);
intr_info_field = vmcs_read32(VM_ENTRY_INTR_INFO_FIELD);
idtv_info_field = vmcs_read32(IDT_VECTORING_INFO_FIELD);