diff mbox series

[4/4] KVM/VMX: Fold handle_interrupt_nmi_irqoff() into its solo caller

Message ID 20210426230949.3561-5-jiangshanlai@gmail.com (mailing list archive)
State New, archived
Headers show
Series x86: Don't invoke asm_exc_nmi() on the kernel stack | expand

Commit Message

Lai Jiangshan April 26, 2021, 11:09 p.m. UTC 
From: Lai Jiangshan <laijs@linux.alibaba.com>

The function handle_interrupt_nmi_irqoff() is called only once and
it doesn't handle for NMI, so its name is outdated.

Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
 arch/x86/kvm/vmx/vmx.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

Comments

Thomas Gleixner April 30, 2021, 9:03 a.m. UTC | #1 
Lai,

On Tue, Apr 27 2021 at 07:09, Lai Jiangshan wrote:
>  	u32 intr_info = vmx_get_intr_info(&vmx->vcpu);
> @@ -6427,12 +6417,19 @@ static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
>  static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu)
>  {
>  	u32 intr_info = vmx_get_intr_info(vcpu);
> +	unsigned int vector;
> +	gate_desc *desc;
>  
>  	if (WARN_ONCE(!is_external_intr(intr_info),
>  	    "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info))
>  		return;
>  
> -	handle_interrupt_nmi_irqoff(vcpu, intr_info);
> +	vector = intr_info & INTR_INFO_VECTOR_MASK;
> +	desc = (gate_desc *)host_idt_base + vector;
> +
> +	kvm_before_interrupt(vcpu);
> +	vmx_do_interrupt_nmi_irqoff(gate_offset(desc));
> +	kvm_after_interrupt(vcpu);

So the previous patch does:

+               kvm_before_interrupt(&vmx->vcpu);
+               vmx_do_interrupt_nmi_irqoff((unsigned long)asm_noist_exc_nmi);
+               kvm_after_interrupt(&vmx->vcpu);

What is this idt gate descriptor dance for in this code?

Thanks,

        tglx
Paolo Bonzini April 30, 2021, 9:06 a.m. UTC | #2 
On 30/04/21 11:03, Thomas Gleixner wrote:
> Lai,
> 
> On Tue, Apr 27 2021 at 07:09, Lai Jiangshan wrote:
>>   	u32 intr_info = vmx_get_intr_info(&vmx->vcpu);
>> @@ -6427,12 +6417,19 @@ static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
>>   static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu)
>>   {
>>   	u32 intr_info = vmx_get_intr_info(vcpu);
>> +	unsigned int vector;
>> +	gate_desc *desc;
>>   
>>   	if (WARN_ONCE(!is_external_intr(intr_info),
>>   	    "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info))
>>   		return;
>>   
>> -	handle_interrupt_nmi_irqoff(vcpu, intr_info);
>> +	vector = intr_info & INTR_INFO_VECTOR_MASK;
>> +	desc = (gate_desc *)host_idt_base + vector;
>> +
>> +	kvm_before_interrupt(vcpu);
>> +	vmx_do_interrupt_nmi_irqoff(gate_offset(desc));
>> +	kvm_after_interrupt(vcpu);
> 
> So the previous patch does:
> 
> +               kvm_before_interrupt(&vmx->vcpu);
> +               vmx_do_interrupt_nmi_irqoff((unsigned long)asm_noist_exc_nmi);
> +               kvm_after_interrupt(&vmx->vcpu);
> 
> What is this idt gate descriptor dance for in this code?

NMIs are sent through a different vmexit code (the same one as 
exceptions).  This one is for interrupts.

Paolo
Thomas Gleixner April 30, 2021, 11:28 p.m. UTC | #3 
On Fri, Apr 30 2021 at 11:06, Paolo Bonzini wrote:

> On 30/04/21 11:03, Thomas Gleixner wrote:
>> Lai,
>> 
>> On Tue, Apr 27 2021 at 07:09, Lai Jiangshan wrote:
>>>   	u32 intr_info = vmx_get_intr_info(&vmx->vcpu);
>>> @@ -6427,12 +6417,19 @@ static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
>>>   static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu)
>>>   {
>>>   	u32 intr_info = vmx_get_intr_info(vcpu);
>>> +	unsigned int vector;
>>> +	gate_desc *desc;
>>>   
>>>   	if (WARN_ONCE(!is_external_intr(intr_info),
>>>   	    "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info))
>>>   		return;
>>>   
>>> -	handle_interrupt_nmi_irqoff(vcpu, intr_info);
>>> +	vector = intr_info & INTR_INFO_VECTOR_MASK;
>>> +	desc = (gate_desc *)host_idt_base + vector;
>>> +
>>> +	kvm_before_interrupt(vcpu);
>>> +	vmx_do_interrupt_nmi_irqoff(gate_offset(desc));
>>> +	kvm_after_interrupt(vcpu);
>> 
>> So the previous patch does:
>> 
>> +               kvm_before_interrupt(&vmx->vcpu);
>> +               vmx_do_interrupt_nmi_irqoff((unsigned long)asm_noist_exc_nmi);
>> +               kvm_after_interrupt(&vmx->vcpu);
>> 
>> What is this idt gate descriptor dance for in this code?
>
> NMIs are sent through a different vmexit code (the same one as 
> exceptions).  This one is for interrupts.

Duh. Yes. The ability to read is clearly an advantage...
diff mbox series

Patch

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 96e59d912637..92c22211203e 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6396,16 +6396,6 @@  static void vmx_apicv_post_state_restore(struct kvm_vcpu *vcpu)
 
 void vmx_do_interrupt_nmi_irqoff(unsigned long entry);
 
-static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu, u32 intr_info)
-{
-	unsigned int vector = intr_info & INTR_INFO_VECTOR_MASK;
-	gate_desc *desc = (gate_desc *)host_idt_base + vector;
-
-	kvm_before_interrupt(vcpu);
-	vmx_do_interrupt_nmi_irqoff(gate_offset(desc));
-	kvm_after_interrupt(vcpu);
-}
-
 static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
 {
 	u32 intr_info = vmx_get_intr_info(&vmx->vcpu);
@@ -6427,12 +6417,19 @@  static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
 static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu)
 {
 	u32 intr_info = vmx_get_intr_info(vcpu);
+	unsigned int vector;
+	gate_desc *desc;
 
 	if (WARN_ONCE(!is_external_intr(intr_info),
 	    "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info))
 		return;
 
-	handle_interrupt_nmi_irqoff(vcpu, intr_info);
+	vector = intr_info & INTR_INFO_VECTOR_MASK;
+	desc = (gate_desc *)host_idt_base + vector;
+
+	kvm_before_interrupt(vcpu);
+	vmx_do_interrupt_nmi_irqoff(gate_offset(desc));
+	kvm_after_interrupt(vcpu);
 }
 
 static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu)