linux-kernel - Re: [RFC PATCH v5 040/104] KVM: VMX: Split out guts of EPT violation to common/exposed function

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Date:   Tue, 5 Apr 2022 16:43:43 +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 040/104] KVM: VMX: Split out guts of EPT violation
 to common/exposed function

On 3/4/22 20:48, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
> 
> The difference of TDX EPT violation is how to retrieve information, GPA,
> and exit qualification.  To share the code to handle EPT violation, split
> out the guts of EPT violation handler so that VMX/TDX exit handler can call
> it after retrieving GPA and exit qualification.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>   arch/x86/kvm/vmx/common.h | 35 +++++++++++++++++++++++++++++++++++
>   arch/x86/kvm/vmx/vmx.c    | 34 ++++++----------------------------
>   2 files changed, 41 insertions(+), 28 deletions(-)
>   create mode 100644 arch/x86/kvm/vmx/common.h
> 
> diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
> new file mode 100644
> index 000000000000..1052b3c93eb8
> --- /dev/null
> +++ b/arch/x86/kvm/vmx/common.h
> @@ -0,0 +1,35 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef __KVM_X86_VMX_COMMON_H
> +#define __KVM_X86_VMX_COMMON_H
> +
> +#include <linux/kvm_host.h>
> +
> +#include "mmu.h"
> +
> +static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
> +					     unsigned long exit_qualification)
> +{
> +	u64 error_code;
> +
> +	/* Is it a read fault? */
> +	error_code = (exit_qualification & EPT_VIOLATION_ACC_READ)
> +		     ? PFERR_USER_MASK : 0;
> +	/* Is it a write fault? */
> +	error_code |= (exit_qualification & EPT_VIOLATION_ACC_WRITE)
> +		      ? PFERR_WRITE_MASK : 0;
> +	/* Is it a fetch fault? */
> +	error_code |= (exit_qualification & EPT_VIOLATION_ACC_INSTR)
> +		      ? PFERR_FETCH_MASK : 0;
> +	/* ept page table entry is present? */
> +	error_code |= (exit_qualification &
> +		       (EPT_VIOLATION_READABLE | EPT_VIOLATION_WRITABLE |
> +			EPT_VIOLATION_EXECUTABLE))
> +		      ? PFERR_PRESENT_MASK : 0;
> +
> +	error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) != 0 ?
> +	       PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
> +
> +	return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0);
> +}
> +
> +#endif /* __KVM_X86_VMX_COMMON_H */
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 7838cd177f0e..0edeeed0b4c8 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -50,6 +50,7 @@
>   #include <asm/vmx.h>
>   
>   #include "capabilities.h"
> +#include "common.h"
>   #include "cpuid.h"
>   #include "evmcs.h"
>   #include "hyperv.h"
> @@ -5381,11 +5382,10 @@ static int handle_task_switch(struct kvm_vcpu *vcpu)
>   
>   static int handle_ept_violation(struct kvm_vcpu *vcpu)
>   {
> -	unsigned long exit_qualification;
> -	gpa_t gpa;
> -	u64 error_code;
> +	unsigned long exit_qualification = vmx_get_exit_qual(vcpu);
> +	gpa_t gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
>   
> -	exit_qualification = vmx_get_exit_qual(vcpu);
> +	trace_kvm_page_fault(gpa, exit_qualification);
>   
>   	/*
>   	 * EPT violation happened while executing iret from NMI,
> @@ -5394,31 +5394,9 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
>   	 * AAK134, BY25.
>   	 */
>   	if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
> -			enable_vnmi &&
> -			(exit_qualification & INTR_INFO_UNBLOCK_NMI))
> +	    enable_vnmi && (exit_qualification & INTR_INFO_UNBLOCK_NMI))
>   		vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, GUEST_INTR_STATE_NMI);
>   
> -	gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
> -	trace_kvm_page_fault(gpa, exit_qualification);
> -
> -	/* Is it a read fault? */
> -	error_code = (exit_qualification & EPT_VIOLATION_ACC_READ)
> -		     ? PFERR_USER_MASK : 0;
> -	/* Is it a write fault? */
> -	error_code |= (exit_qualification & EPT_VIOLATION_ACC_WRITE)
> -		      ? PFERR_WRITE_MASK : 0;
> -	/* Is it a fetch fault? */
> -	error_code |= (exit_qualification & EPT_VIOLATION_ACC_INSTR)
> -		      ? PFERR_FETCH_MASK : 0;
> -	/* ept page table entry is present? */
> -	error_code |= (exit_qualification &
> -		       (EPT_VIOLATION_READABLE | EPT_VIOLATION_WRITABLE |
> -			EPT_VIOLATION_EXECUTABLE))
> -		      ? PFERR_PRESENT_MASK : 0;
> -
> -	error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) != 0 ?
> -	       PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
> -
>   	vcpu->arch.exit_qualification = exit_qualification;
>   
>   	/*
> @@ -5432,7 +5410,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
>   	if (unlikely(allow_smaller_maxphyaddr && kvm_vcpu_is_illegal_gpa(vcpu, gpa)))
>   		return kvm_emulate_instruction(vcpu, 0);
>   
> -	return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0);
> +	return __vmx_handle_ept_violation(vcpu, gpa, exit_qualification);
>   }
>   
>   static int handle_ept_misconfig(struct kvm_vcpu *vcpu)

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