linux-kernel - Re: [RFC PATCH v5 081/104] KVM: VMX: Modify NMI and INTR handlers to take intr

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Message-ID: <afbb7b38-11d9-0cfb-2c7b-df17a9074e3b@redhat.com>
Date:   Wed, 6 Apr 2022 14:49:47 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...il.com, Jim Mattson <jmattson@...gle.com>,
        erdemaktas@...gle.com, Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [RFC PATCH v5 081/104] KVM: VMX: Modify NMI and INTR handlers to
 take intr_info as function argument

On 3/4/22 20:49, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
> 
> TDX uses different ABI to get information about VM exit.  Pass intr_info to
> the NMI and INTR handlers instead of pulling it from vcpu_vmx in
> preparation for sharing the bulk of the handlers with TDX.
> 
> When the guest TD exits to VMM, RAX holds status and exit reason, RCX holds
> exit qualification etc rather than the VMCS fields because VMM doesn't have
> access to the VMCS.  The eventual code will be
> 
> VMX:
>    - get exit reason, intr_info, exit_qualification, and etc from VMCS
>    - call NMI/INTR handlers (common code)
> 
> TDX:
>    - get exit reason, intr_info, exit_qualification, and etc from guest
>      registers
>    - call NMI/INTR handlers (common code)
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>   arch/x86/kvm/vmx/vmx.c | 17 ++++++++---------
>   1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 4bd1e61b8d45..008400927144 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6442,28 +6442,27 @@ static void handle_nm_fault_irqoff(struct kvm_vcpu *vcpu)
>   		rdmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err);
>   }
>   
> -static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
> +static void handle_exception_nmi_irqoff(struct kvm_vcpu *vcpu, u32 intr_info)
>   {
>   	const unsigned long nmi_entry = (unsigned long)asm_exc_nmi_noist;
> -	u32 intr_info = vmx_get_intr_info(&vmx->vcpu);
>   
>   	/* if exit due to PF check for async PF */
>   	if (is_page_fault(intr_info))
> -		vmx->vcpu.arch.apf.host_apf_flags = kvm_read_and_reset_apf_flags();
> +		vcpu->arch.apf.host_apf_flags = kvm_read_and_reset_apf_flags();
>   	/* if exit due to NM, handle before interrupts are enabled */
>   	else if (is_nm_fault(intr_info))
> -		handle_nm_fault_irqoff(&vmx->vcpu);
> +		handle_nm_fault_irqoff(vcpu);
>   	/* Handle machine checks before interrupts are enabled */
>   	else if (is_machine_check(intr_info))
>   		kvm_machine_check();
>   	/* We need to handle NMIs before interrupts are enabled */
>   	else if (is_nmi(intr_info))
> -		handle_interrupt_nmi_irqoff(&vmx->vcpu, nmi_entry);
> +		handle_interrupt_nmi_irqoff(vcpu, nmi_entry);
>   }
>   
> -static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu)
> +static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu,
> +					     u32 intr_info)
>   {
> -	u32 intr_info = vmx_get_intr_info(vcpu);
>   	unsigned int vector = intr_info & INTR_INFO_VECTOR_MASK;
>   	gate_desc *desc = (gate_desc *)host_idt_base + vector;
>   
> @@ -6482,9 +6481,9 @@ void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu)
>   		return;
>   
>   	if (vmx->exit_reason.basic == EXIT_REASON_EXTERNAL_INTERRUPT)
> -		handle_external_interrupt_irqoff(vcpu);
> +		handle_external_interrupt_irqoff(vcpu, vmx_get_intr_info(vcpu));
>   	else if (vmx->exit_reason.basic == EXIT_REASON_EXCEPTION_NMI)
> -		handle_exception_nmi_irqoff(vmx);
> +		handle_exception_nmi_irqoff(vcpu, vmx_get_intr_info(vcpu));
>   }
>   
>   /*

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>