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From: Wincy Van <fanwenyi0529@gmail.com>
Date: Wed, 28 Jan 2015 13:54:30 +0800
Message-ID: <CACzj_yUn8yMY1iW2Umd_nYX29jw1vyuPd=m+jfx55ZwXXUPTBw@mail.gmail.com>
Subject: Re: [PATCH v3 6/6] KVM: nVMX: Enable nested posted interrupt processing.
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "gleb@kernel.org" <gleb@kernel.org>,
        "Zhang, Yang Z" <yang.z.zhang@intel.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Wanpeng Li <wanpeng.li@linux.intel.com>,
        Jan Kiszka <jan.kiszka@web.de>
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On Wed, Jan 28, 2015 at 5:55 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
>
> On 24/01/2015 11:24, Wincy Van wrote:
>>         if (!nested_cpu_has_virt_x2apic_mode(vmcs12) &&
>>             !nested_cpu_has_apic_reg_virt(vmcs12) &&
>> -           !nested_cpu_has_vid(vmcs12))
>> +           !nested_cpu_has_vid(vmcs12) &&
>> +           !nested_cpu_has_posted_intr(vmcs12))
>>                 return 0;
>>
>>         if (nested_cpu_has_virt_x2apic_mode(vmcs12))
>>                 r = nested_vmx_check_virt_x2apic(vcpu, vmcs12);
>>         if (nested_cpu_has_vid(vmcs12))
>>                 r |= nested_vmx_check_vid(vcpu, vmcs12);
>> +       if (nested_cpu_has_posted_intr(vmcs12))
>> +               r |= nested_vmx_check_posted_intr(vcpu, vmcs12);
>
> These "if"s are always true.
>

Why? L1 may config these features seperately, we should check them one by one.
e.g.  L1 may enable posted interrupt processing and virtual interrupt
delivery, but leaving virtualize x2apic mode disabled, then
nested_cpu_has_virt_x2apic_mode will return false.

> Paolo