linux-kernel - Re: [RFC PATCH 03/13] KVM: nSVM: Split nested_svm_transition_tlb

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Message-ID: <de4a5000d03a4697a419231d766f95dfd1cbe7c6.camel@redhat.com>
Date: Fri, 28 Feb 2025 20:34:20 -0500
From: Maxim Levitsky <mlevitsk@...hat.com>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>, Sean Christopherson
 <seanjc@...gle.com>,  Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 03/13] KVM: nSVM: Split
 nested_svm_transition_tlb_flush() into entry/exit fns

On Wed, 2025-02-05 at 18:23 +0000, Yosry Ahmed wrote:
> The handling for the entry and exit TLB flushes will diverge
> significantly in the following changes. Instead of adding an 'is_vmenter'
> argument like nested_vmx_transition_tlb_flush(), just split the function
> into two variants for 'entry' and 'exit'.
> 
> No functional change intended.
> 
> Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
> ---
>  arch/x86/kvm/svm/nested.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index bbe4f3ac9f250..2eba36af44f22 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -482,7 +482,7 @@ static void nested_save_pending_event_to_vmcb12(struct vcpu_svm *svm,
>  	vmcb12->control.exit_int_info = exit_int_info;
>  }
>  
> -static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu)
> +static void nested_svm_entry_tlb_flush(struct kvm_vcpu *vcpu)
>  {
>  	/* Handle pending Hyper-V TLB flush requests */
>  	kvm_hv_nested_transtion_tlb_flush(vcpu, npt_enabled);
> @@ -503,6 +503,16 @@ static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu)
>  	kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu);
>  }
>  
> +static void nested_svm_exit_tlb_flush(struct kvm_vcpu *vcpu)
> +{
> +	/* Handle pending Hyper-V TLB flush requests */
> +	kvm_hv_nested_transtion_tlb_flush(vcpu, npt_enabled);
> +
> +	/* See nested_svm_entry_tlb_flush() */
> +	kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
> +	kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu);
> +}
> +
>  /*
>   * Load guest's/host's cr3 on nested vmentry or vmexit. @nested_npt is true
>   * if we are emulating VM-Entry into a guest with NPT enabled.
> @@ -645,7 +655,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm,
>  	u32 pause_count12;
>  	u32 pause_thresh12;
>  
> -	nested_svm_transition_tlb_flush(vcpu);
> +	nested_svm_entry_tlb_flush(vcpu);
>  
>  	/* Enter Guest-Mode */
>  	enter_guest_mode(vcpu);
> @@ -1131,7 +1141,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
>  
>  	kvm_vcpu_unmap(vcpu, &map);
>  
> -	nested_svm_transition_tlb_flush(vcpu);
> +	nested_svm_exit_tlb_flush(vcpu);
>  
>  	nested_svm_uninit_mmu_context(vcpu);
>  

Looks reasonable,

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky