From: Anthony Liguori <aliguori@us.ibm.com>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: KVM <kvm@vger.kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Marcelo Tosatti <mtosatti@redhat.com>, X86 <x86@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Avi Kivity <avi@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH 1/1] kvm : vmx : Remove yield_on_hlt
Date: Tue, 07 Feb 2012 12:04:14 -0600 [thread overview]
Message-ID: <4F31679E.3040408@us.ibm.com> (raw)
In-Reply-To: <20120207174919.3848.99779.sendpatchset@oc5400248562.ibm.com>
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<raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Anthony Liguori <aliguori@us.ibm.com>
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)
next prev parent reply other threads:[~2012-02-07 18:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-07 17:49 [PATCH 1/1] kvm : vmx : Remove yield_on_hlt Raghavendra K T
2012-02-07 18:04 ` Anthony Liguori [this message]
2012-02-07 21:15 ` Marcelo Tosatti
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