linux-kernel - Re: [PATCH v1 13/23] KVM: VMX: Handle VMX nested exception for FRED

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Message-ID: <ZVMkVmBPVfaMjDTL@chao-email>
Date:   Tue, 14 Nov 2023 15:40:06 +0800
From:   Chao Gao <chao.gao@...el.com>
To:     Xin Li <xin3.li@...el.com>
CC:     <kvm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-hyperv@...r.kernel.org>,
        <linux-kselftest@...r.kernel.org>, <seanjc@...gle.com>,
        <pbonzini@...hat.com>, <corbet@....net>, <kys@...rosoft.com>,
        <haiyangz@...rosoft.com>, <wei.liu@...nel.org>,
        <decui@...rosoft.com>, <tglx@...utronix.de>, <mingo@...hat.com>,
        <bp@...en8.de>, <dave.hansen@...ux.intel.com>, <x86@...nel.org>,
        <hpa@...or.com>, <vkuznets@...hat.com>, <peterz@...radead.org>,
        <ravi.v.shankar@...el.com>
Subject: Re: [PATCH v1 13/23] KVM: VMX: Handle VMX nested exception for FRED

> 	/* Require Write-Back (WB) memory type for VMCS accesses. */
>@@ -7313,11 +7328,12 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
> 			}
> 		}
> 
>-		if (idt_vectoring_info & VECTORING_INFO_DELIVER_CODE_MASK) {
>-			u32 err = vmcs_read32(error_code_field);
>-			kvm_requeue_exception_e(vcpu, vector, err);
>-		} else
>-			kvm_requeue_exception(vcpu, vector);
>+		if (idt_vectoring_info & VECTORING_INFO_DELIVER_CODE_MASK)
>+			kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field),
>+						idt_vectoring_info & INTR_INFO_NESTED_EXCEPTION_MASK);
>+		else
>+			kvm_requeue_exception(vcpu, vector,
>+					      idt_vectoring_info & INTR_INFO_NESTED_EXCEPTION_MASK);

Exiting-event identification can also have bit 13 set, indicating a nested
exception encountered and caused VM-exit. when reinjecting the exception to
guests, kvm needs to set the "nested" bit, right? I suspect some changes
to e.g., handle_exception_nmi() are needed.