linux-kernel - Re: [PATCH 6/6] KVM: VMX: enable IPI virtualization

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <8aed2541-082d-d115-09ac-e7fcc05f96dc@redhat.com>
Date:   Fri, 16 Jul 2021 11:52:10 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Zeng Guang <guang.zeng@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Kim Phillips <kim.phillips@....com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jethro Beekman <jethro@...tanix.com>,
        Kai Huang <kai.huang@...el.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Robert Hu <robert.hu@...el.com>, Gao Chao <chao.gao@...el.com>,
        Emanuele Giuseppe Esposito <eesposit@...hat.com>
Subject: Re: [PATCH 6/6] KVM: VMX: enable IPI virtualization

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