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.
Changelog:
Remove the support for yield_on_hlt.
Signed-off-by: Raghavendra K T <[email protected]>
---
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d29216c..2fb3009 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)
@@ -2399,7 +2384,7 @@ 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 |
@@ -2414,9 +2399,6 @@ 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;
@@ -4003,7 +3985,6 @@ 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)
@@ -4035,7 +4016,6 @@ 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)
On 02/07/2012 11:49 AM, Raghavendra K T wrote:
> 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.
>
> Changelog:
> Remove the support for yield_on_hlt.
>
> Signed-off-by: Raghavendra K T<[email protected]>
Acked-by: Anthony Liguori <[email protected]>
Regards,
Anthony Liguori
> ---
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index d29216c..2fb3009 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)
> @@ -2399,7 +2384,7 @@ 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 |
> @@ -2414,9 +2399,6 @@ 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;
> @@ -4003,7 +3985,6 @@ 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)
> @@ -4035,7 +4016,6 @@ 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)
On Tue, Feb 07, 2012 at 11:19:20PM +0530, Raghavendra K T wrote:
> 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.
>
> Changelog:
> Remove the support for yield_on_hlt.
>
> Signed-off-by: Raghavendra K T <[email protected]>
Applied, thanks.