KVM: VMX: remove yield_on_hlt

yield_on_hlt was introduced for CPU bandwidth capping. Now it is
redundant with CFS hardlimit.

yield_on_hlt also complicates the scenario in paravirtual environment,
that needs to trap halt. for e.g. paravirtualized ticket spinlocks.

Acked-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 1 insertions, 21 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 575fb742a6fc..d2bd719925a6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -70,9 +70,6 @@ module_param(emulate_invalid_guest_state, bool, S_IRUGO);
 static bool __read_mostly vmm_exclusive = 1;
 module_param(vmm_exclusive, bool, S_IRUGO);
 
-static bool __read_mostly yield_on_hlt = 1;
-module_param(yield_on_hlt, bool, S_IRUGO);
-
 static bool __read_mostly fasteoi = 1;
 module_param(fasteoi, bool, S_IRUGO);
 
@@ -1655,17 +1652,6 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
         vmx_set_interrupt_shadow(vcpu, 0);
 }
 
-static void vmx_clear_hlt(struct kvm_vcpu *vcpu)
-{
-        /* Ensure that we clear the HLT state in the VMCS.  We don't need to
-         * explicitly skip the instruction because if the HLT state is set, then
-         * the instruction is already executing and RIP has already been
-         * advanced. */
-        if (!yield_on_hlt &&
-            vmcs_read32(GUEST_ACTIVITY_STATE) == GUEST_ACTIVITY_HLT)
-                vmcs_write32(GUEST_ACTIVITY_STATE, GUEST_ACTIVITY_ACTIVE);
-}
-
 /*
  * KVM wants to inject page-faults which it got to the guest. This function
  * checks whether in a nested guest, we need to inject them to L1 or L2.
@@ -1718,7 +1704,6 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
                 intr_info |= INTR_TYPE_HARD_EXCEPTION;
 
         vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
-        vmx_clear_hlt(vcpu);
 }
 
 static bool vmx_rdtscp_supported(void)
@@ -2405,7 +2390,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
                                 &_pin_based_exec_control) < 0)
                 return -EIO;
 
-        min =
+        min = CPU_BASED_HLT_EXITING |
 #ifdef CONFIG_X86_64
               CPU_BASED_CR8_LOAD_EXITING |
               CPU_BASED_CR8_STORE_EXITING |
@@ -2420,9 +2405,6 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
               CPU_BASED_INVLPG_EXITING |
               CPU_BASED_RDPMC_EXITING;
 
-        if (yield_on_hlt)
-                min |= CPU_BASED_HLT_EXITING;
-
         opt = CPU_BASED_TPR_SHADOW |
               CPU_BASED_USE_MSR_BITMAPS |
               CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
@@ -4009,7 +3991,6 @@ static void vmx_inject_irq(struct kvm_vcpu *vcpu)
         } else
                 intr |= INTR_TYPE_EXT_INTR;
         vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr);
-        vmx_clear_hlt(vcpu);
 }
 
 static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
@@ -4041,7 +4022,6 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
         }
         vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
                         INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK | NMI_VECTOR);
-        vmx_clear_hlt(vcpu);
 }
 
 static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)