linux-kernel - Re: [PATCH v7 1/3] KVM: x86: Add a wbinvd helper

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Message-ID: <5fb9fa5e-5769-3ad8-32d8-e4a045f041a1@amd.com>
Date: Thu, 6 Feb 2025 16:03:48 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Zheyun Shen <szy0127@...u.edu.cn>, seanjc@...gle.com,
 pbonzini@...hat.com, tglx@...utronix.de, kevinloughlin@...gle.com,
 mingo@...hat.com, bp@...en8.de
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/3] KVM: x86: Add a wbinvd helper

On 1/27/25 19:53, Zheyun Shen wrote:
> At the moment open-coded calls to on_each_cpu_mask() are used when
> emulating wbinvd. A subsequent patch needs the same behavior and the
> helper prevents callers from preparing some idential parameters.
> 
> Signed-off-by: Zheyun Shen <szy0127@...u.edu.cn>

Not sure if this wouldn't be better living in the same files that
wbinvd_on_all_cpus() lives, so I'll leave it up to the maintainers.

Reviewed-by: Tom Lendacky <thomas.lendacky@....com>

> ---
>  arch/x86/kvm/x86.c | 9 +++++++--
>  arch/x86/kvm/x86.h | 1 +
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 2e7134809..b635e0e5c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8231,8 +8231,7 @@ static int kvm_emulate_wbinvd_noskip(struct kvm_vcpu *vcpu)
>  		int cpu = get_cpu();
>  
>  		cpumask_set_cpu(cpu, vcpu->arch.wbinvd_dirty_mask);
> -		on_each_cpu_mask(vcpu->arch.wbinvd_dirty_mask,
> -				wbinvd_ipi, NULL, 1);
> +		wbinvd_on_many_cpus(vcpu->arch.wbinvd_dirty_mask);
>  		put_cpu();
>  		cpumask_clear(vcpu->arch.wbinvd_dirty_mask);
>  	} else
> @@ -13964,6 +13963,12 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
>  }
>  EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);
>  
> +void wbinvd_on_many_cpus(struct cpumask *mask)
> +{
> +	on_each_cpu_mask(mask, wbinvd_ipi, NULL, 1);
> +}
> +EXPORT_SYMBOL_GPL(wbinvd_on_many_cpus);
> +
>  EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_entry);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index ec623d23d..8f715e14b 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -611,5 +611,6 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu *vcpu, gpa_t src, unsigned int bytes,
>  int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
>  			 unsigned int port, void *data,  unsigned int count,
>  			 int in);
> +void wbinvd_on_many_cpus(struct cpumask *mask);
>  
>  #endif