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To:     Zeng Guang <guang.zeng@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Kim Phillips <kim.phillips@amd.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Jethro Beekman <jethro@fortanix.com>,
        Kai Huang <kai.huang@intel.com>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org,
        Robert Hu <robert.hu@intel.com>, Gao Chao <chao.gao@intel.com>,
        Emanuele Giuseppe Esposito <eesposit@redhat.com>
References: <20210716064808.14757-1-guang.zeng@intel.com>
 <20210716064808.14757-7-guang.zeng@intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 6/6] KVM: VMX: enable IPI virtualization
Message-ID: <8aed2541-082d-d115-09ac-e7fcc05f96dc@redhat.com>
Date:   Fri, 16 Jul 2021 11:52:10 +0200
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On 16/07/21 08:48, Zeng Guang wrote:
>  
> +	if (!(_cpu_based_3rd_exec_control & TERTIARY_EXEC_IPI_VIRT))
> +		enable_ipiv = 0;
> +
>   	}

Please move this to hardware_setup(), using a new function 
cpu_has_vmx_ipiv() in vmx/capabilities.h.

>  	if (_cpu_based_exec_control & CPU_BASED_ACTIVATE_TERTIARY_CONTROLS) {
> -		u64 opt3 = 0;
> +		u64 opt3 = enable_ipiv ? TERTIARY_EXEC_IPI_VIRT : 0;
>  		u64 min3 = 0;

I like the idea of changing opt3, but it's different from how 
setup_vmcs_config works for the other execution controls.  Let me think 
if it makes sense to clean this up, and move the handling of other 
module parameters from hardware_setup() to setup_vmcs_config().

> +
> +	if (vmx->ipiv_active)
> +		install_pid(vmx);

This should be if (enable_ipiv) instead, I think.

In fact, in all other places that are using vmx->ipiv_active, you can 
actually replace it with enable_ipiv; they are all reached only with 
kvm_vcpu_apicv_active(vcpu) == true.

> +	if (!enable_apicv) {
> +		enable_ipiv = 0;
> +		vmcs_config.cpu_based_3rd_exec_ctrl &= ~TERTIARY_EXEC_IPI_VIRT;
> +	}

The assignment to vmcs_config.cpu_based_3rd_exec_ctrl should not be 
necessary; kvm_vcpu_apicv_active will always be false in that case and 
IPI virtualization would never be enabled.

Paolo