Commit 10166744 authored by Raghavendra K T's avatar Raghavendra K T Committed by Avi Kivity
Browse files

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: default avatarAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: default avatarRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent e26101b1

arch/x86/kvm/vmx.c

+1 −21
Original line number Diff line number Diff line
@@ -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)

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