linux-kernel - Re: [RFC PATCH 12/24] KVM: x86: hyper-v: Pass is_guest_mode to kvm_hv_vcpu_purge_flush

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Message-ID: <e255fa3ee192b136eeef7e9a63e8d1506d5e85a8.camel@redhat.com>
Date: Thu, 03 Apr 2025 16:09:40 -0400
From: Maxim Levitsky <mlevitsk@...hat.com>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>, Sean Christopherson
 <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jim Mattson <jmattson@...gle.com>, 
 Vitaly Kuznetsov <vkuznets@...hat.com>, Rik van Riel <riel@...riel.com>,
 Tom Lendacky <thomas.lendacky@....com>,  x86@...nel.org,
 kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 12/24] KVM: x86: hyper-v: Pass is_guest_mode to
 kvm_hv_vcpu_purge_flush_tlb()

On Wed, 2025-03-26 at 19:36 +0000, Yosry Ahmed wrote:
> Instead of calling is_guest_mode() inside kvm_hv_vcpu_purge_flush_tlb()
> pass the value from the caller. Future changes will pass different
> values than is_guest_mode(vcpu).
> 
> No functional change intended.
> 
> Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
> ---
>  arch/x86/kvm/hyperv.h  | 8 +++++---
>  arch/x86/kvm/svm/svm.c | 2 +-
>  arch/x86/kvm/x86.c     | 2 +-
>  3 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
> index 913bfc96959cb..be715deaeb003 100644
> --- a/arch/x86/kvm/hyperv.h
> +++ b/arch/x86/kvm/hyperv.h
> @@ -203,14 +203,15 @@ static inline struct kvm_vcpu_hv_tlb_flush_fifo *kvm_hv_get_tlb_flush_fifo(struc
>  	return &hv_vcpu->tlb_flush_fifo[i];
>  }
>  
> -static inline void kvm_hv_vcpu_purge_flush_tlb(struct kvm_vcpu *vcpu)
> +static inline void kvm_hv_vcpu_purge_flush_tlb(struct kvm_vcpu *vcpu,
> +					       bool is_guest_mode)
>  {
>  	struct kvm_vcpu_hv_tlb_flush_fifo *tlb_flush_fifo;
>  
>  	if (!to_hv_vcpu(vcpu) || !kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu))
>  		return;
>  
> -	tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(vcpu, is_guest_mode(vcpu));
> +	tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(vcpu, is_guest_mode);
>  
>  	kfifo_reset_out(&tlb_flush_fifo->entries);
>  }
> @@ -285,7 +286,8 @@ static inline int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>  {
>  	return HV_STATUS_ACCESS_DENIED;
>  }
> -static inline void kvm_hv_vcpu_purge_flush_tlb(struct kvm_vcpu *vcpu) {}
> +static inline void kvm_hv_vcpu_purge_flush_tlb(struct kvm_vcpu *vcpu,
> +					       bool is_guest_mode) {}
>  static inline bool kvm_hv_synic_has_vector(struct kvm_vcpu *vcpu, int vector)
>  {
>  	return false;
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index e664d8428c792..865c5ce4fa473 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -4025,7 +4025,7 @@ static void svm_flush_tlb_asid(struct kvm_vcpu *vcpu)
>  	 * A TLB flush for the current ASID flushes both "host" and "guest" TLB
>  	 * entries, and thus is a superset of Hyper-V's fine grained flushing.
>  	 */
> -	kvm_hv_vcpu_purge_flush_tlb(vcpu);
> +	kvm_hv_vcpu_purge_flush_tlb(vcpu, is_guest_mode(vcpu));
>  
>  	/*
>  	 * Flush only the current ASID even if the TLB flush was invoked via
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 182f18ebc62f3..469a8e5526902 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3615,7 +3615,7 @@ static void kvm_vcpu_flush_tlb_guest(struct kvm_vcpu *vcpu)
>  	 * Flushing all "guest" TLB is always a superset of Hyper-V's fine
>  	 * grained flushing.
>  	 */
> -	kvm_hv_vcpu_purge_flush_tlb(vcpu);
> +	kvm_hv_vcpu_purge_flush_tlb(vcpu, is_guest_mode(vcpu));
>  }
>  
>  

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

Best regards,
	Maxim Levitsky