linux-kernel - Re: [PATCH v18 054/121] KVM: VMX: Split out guts of EPT violation to common/exposed function

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Message-ID: <45b6ba60-276e-4826-b3e4-20d3854558b1@linux.intel.com>
Date: Sun, 4 Feb 2024 16:53:27 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: isaku.yamahata@...el.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
 erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
 Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
 chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com,
 Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH v18 054/121] KVM: VMX: Split out guts of EPT violation to
 common/exposed function



On 1/23/2024 7:53 AM, 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.

Reviewed-by: Binbin Wu <binbin.wu@...ux.intel.com>
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
> Reviewed-by: Kai Huang <kai.huang@...el.com>
> ---
>   arch/x86/kvm/vmx/common.h | 33 +++++++++++++++++++++++++++++++++
>   arch/x86/kvm/vmx/vmx.c    | 25 +++----------------------
>   2 files changed, 36 insertions(+), 22 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..235908f3e044
> --- /dev/null
> +++ b/arch/x86/kvm/vmx/common.h
> @@ -0,0 +1,33 @@
> +/* 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_RWX_MASK)
> +		      ? 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 89f31263fe9c..185e22a2e101 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 "hyperv.h"
>   #include "kvm_onhyperv.h"
> @@ -5779,11 +5780,8 @@ static int handle_task_switch(struct kvm_vcpu *vcpu)
>   
>   static int handle_ept_violation(struct kvm_vcpu *vcpu)
>   {
> -	unsigned long exit_qualification;
> +	unsigned long exit_qualification = vmx_get_exit_qual(vcpu);
>   	gpa_t gpa;
> -	u64 error_code;
> -
> -	exit_qualification = vmx_get_exit_qual(vcpu);
>   
>   	/*
>   	 * EPT violation happened while executing iret from NMI,
> @@ -5798,23 +5796,6 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
>   
>   	gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
>   	trace_kvm_page_fault(vcpu, 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_RWX_MASK)
> -		      ? 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;
>   
>   	/*
> @@ -5828,7 +5809,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
>   	if (unlikely(allow_smaller_maxphyaddr && !kvm_vcpu_is_legal_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)