RE: [PATCH 1/2] x86: Enable ack interrupt on vmexit

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Gleb Natapov wrote on 2012-12-13:
> On Thu, Dec 13, 2012 at 07:54:35AM +0000, Zhang, Yang Z wrote:
>> Gleb Natapov wrote on 2012-12-13:
>>> On Thu, Dec 13, 2012 at 03:29:39PM +0800, Yang Zhang wrote:
>>>> From: Yang Zhang <yang.z.zhang@xxxxxxxxx>
>>>> 
>>>> Ack interrupt on vmexit is required by Posted Interrupt. With it,
>>>> when external interrupt caused vmexit, the cpu will acknowledge the
>>>> interrupt controller and save the interrupt's vector in vmcs. Only
>>>> enable it when posted interrupt is enabled.
>>>> 
>>>> There are several approaches to enable it. This patch uses a simply
>>>> way: re-generate an interrupt via self ipi.
>>>> 
>>>> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
>>>> ---
>>>>  arch/x86/kvm/vmx.c |   20 +++++++++++++++++---
>>>>  1 files changed, 17 insertions(+), 3 deletions(-)
>>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>>>> index 8cd9eb7..6b6bd03 100644
>>>> --- a/arch/x86/kvm/vmx.c
>>>> +++ b/arch/x86/kvm/vmx.c
>>>> @@ -2549,7 +2549,7 @@ static __init int setup_vmcs_config(struct
>>> vmcs_config *vmcs_conf)
>>>>  #ifdef CONFIG_X86_64
>>>>  	min |= VM_EXIT_HOST_ADDR_SPACE_SIZE;
>>>>  #endif
>>>> -	opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT;
>>>> +	opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT |
>>> VM_EXIT_ACK_INTR_ON_EXIT;
>>>>  	if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS,
>>>>  				&_vmexit_control) < 0) 		return -EIO; @@ -3913,6 +3913,7 @@
>>>>  static int vmx_vcpu_setup(struct vcpu_vmx *vmx) 	unsigned long a;
>>>>  #endif 	int i;
>>>> +	u32 vmexit_ctrl = vmcs_config.vmexit_ctrl;
>>>> 
>>>>  	/* I/O */ 	vmcs_write64(IO_BITMAP_A, __pa(vmx_io_bitmap_a)); @@
>>>>  -3996,8 +3997,10 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
>>>>  		vmx->guest_msrs[j].mask = -1ull; 		++vmx->nmsrs; 	}
>>>> -
>>>> -	vmcs_write32(VM_EXIT_CONTROLS, vmcs_config.vmexit_ctrl);
>>>> +
>>>> +	if(!enable_apicv_pi)
>>>> +		vmexit_ctrl &= ~VM_EXIT_ACK_INTR_ON_EXIT;
>>>> +	vmcs_write32(VM_EXIT_CONTROLS, vmexit_ctrl);
>>>> 
>>>>  	/* 22.2.1, 20.8.1 */
>>>>  	vmcs_write32(VM_ENTRY_CONTROLS, vmcs_config.vmentry_ctrl);
>>>> @@ -6267,6 +6270,17 @@ static void vmx_complete_atomic_exit(struct
>>> vcpu_vmx *vmx)
>>>>  		asm("int $2");
>>>>  		kvm_after_handle_nmi(&vmx->vcpu);
>>>>  	}
>>>> +	if ((exit_intr_info & INTR_INFO_INTR_TYPE_MASK) ==
>>>> INTR_TYPE_EXT_INTR && +	    (exit_intr_info & INTR_INFO_VALID_MASK)
>>>> && enable_apicv_pi) { +		unsigned int vector, tmr; + +		vector = 
>>>> exit_intr_info & INTR_INFO_VECTOR_MASK; +		tmr = apic_read(APIC_TMR +
>>>> ((vector &
> ~0x1f)
>>>>>> 1)); +		apic_eoi(); +		if ( !((1 << (vector % 32)) & tmr) )
>>>> +			apic->send_IPI_self(vector); +	}
>>> What happen with the idea to dispatch interrupt through idt without IPI?
>> I am not sure upstream guys will allow to export idt to a module. If it
>> is not a problem, then can do it as you suggested.
>> 
> I replied to that before. No need to export idt to modules. Add function
> to entry_32/64.S that does dispatching and export it instead.
It still need to touch common code. Do you think upstream guys will buy-in this?

>>>> +
>>>>  }
>>>>  
>>>>  static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
>>>> --
>>>> 1.7.1
>>> 
>>> --
>>> 			Gleb.
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe kvm" in
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>> 
>> 
>> Best regards,
>> Yang
>> 
> 
> --
> 			Gleb.


Best regards,
Yang


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