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Message-ID: <9d5c66e6-bc27-026e-fca2-9863ec2bafbd@bytedance.com>
Date:   Tue, 21 Jun 2022 10:23:32 +0800
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Subject: Re: [External] [PATCH v9 9/9] KVM: VMX: enable IPI virtualization
To:     Chao Gao <chao.gao@intel.com>
Cc:     Zeng Guang <guang.zeng@intel.com>,
        Paolo Bonzini <pbonzini@redhat.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>, x86@kernel.org,
        linux-kernel@vger.kernel.org, Robert Hu <robert.hu@intel.com>,
        zhouyibo@bytedance.com
References: <20220419154510.11938-1-guang.zeng@intel.com>
 <cdead652-cbd6-90e4-dab8-9cb18f71a624@bytedance.com>
 <20220620105957.GA9496@gao-cwp>
From:   Shenming Lu <lushenming@bytedance.com>
In-Reply-To: <20220620105957.GA9496@gao-cwp>
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On 20/06/2022 19:00, Chao Gao wrote:
> On Mon, Jun 20, 2022 at 06:02:32PM +0800, Shenming Lu wrote:
>>> +		if (enable_ipiv)
>>> +			tertiary_exec_controls_clearbit(vmx, TERTIARY_EXEC_IPI_VIRT);
>>> +	}
>>>    	vmx_update_msr_bitmap_x2apic(vcpu);
>>>    }
>>
>> Hi, just a small question here:
>>
>> It seems that we clear the TERTIARY_EXEC_IPI_VIRT bit before enabling
>> interception for APIC_ICR when deactivating APICv on some reason.
>> Is there any problem with this sequence?
> 
> Both are done before the next vCPU entry. As long as no guest code can
> run between them (APICv setting takes effect in guest), this sequence
> shouldn't have any problem.

OK. Thanks for reply,

Shenmimg