linux-kernel - RE: [PATCH v3 1/6] KVM: nVMX: Use hardware MSR bitmap

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Date:	Wed, 28 Jan 2015 08:06:19 +0000
From:	"Zhang, Yang Z" <yang.z.zhang@...el.com>
To:	Wincy Van <fanwenyi0529@...il.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	"gleb@...nel.org" <gleb@...nel.org>
CC:	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Jan Kiszka <jan.kiszka@....de>
Subject: RE: [PATCH v3 1/6] KVM: nVMX: Use hardware MSR bitmap

Zhang, Yang Z wrote on 2015-01-28:
> Wincy Van wrote on 2015-01-24:
>> When L2 is using x2apic, we can use virtualize x2apic mode to gain
>> higher performance, especially in apicv case.
>> 
>> This patch also introduces nested_vmx_check_apicv_controls for the
>> nested apicv patches.

Sorry, replied on the wrong thread.:(

>> 
>> Signed-off-by: Wincy Van <fanwenyi0529@...il.com>
>> ---
> 
> ...snip...
> 
>>  static void vmx_disable_intercept_for_msr(u32 msr, bool
>> longmode_only)
> {
>>         if (!longmode_only)
>> @@ -8344,7 +8394,68 @@ static int
>> nested_vmx_check_msr_bitmap_controls(struct kvm_vcpu *vcpu,  static
>> inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
>>                                                struct vmcs12
>> *vmcs12)  {
>> -       return false;
>> +       struct page *page;
>> +       unsigned long *msr_bitmap;
>> +
>> +       if (!nested_cpu_has_virt_x2apic_mode(vmcs12))
>> +               return false;
>> +
>> +       page = nested_get_page(vcpu, vmcs12->msr_bitmap);
>> +       if (!page) {
>> +               WARN_ON(1);
>> +               return false;
>> +       }
>> +       msr_bitmap = (unsigned long *)kmap(page);
>> +       if (!msr_bitmap) {
>> +               nested_release_page_clean(page);
>> +               WARN_ON(1);
>> +               return false;
>> +       }
>> +
>> +       memset(vmx_msr_bitmap_nested, 0xff, PAGE_SIZE);
>> +
>> +       if (nested_cpu_has_virt_x2apic_mode(vmcs12))
>> +               /* TPR is allowed */
>> +               nested_vmx_disable_intercept_for_msr(msr_bitmap,
>> +                               vmx_msr_bitmap_nested,
>> +                               APIC_BASE_MSR + (APIC_TASKPRI >>
>> 4),
>> +                               MSR_TYPE_R | MSR_TYPE_W);
> 
> I didn't understand what this function does? Per my understanding, you
> only need to set the (vmx_msr_bitmap_nested = vmcs01->msr_bitmap |
> vmcs12->msr_bitmap) and inject the nested vmexit to L1 if the bit in
> vmcs12->msr_bitmap is setting. Am I missing some patches?
> 
> Best regards,
> Yang
>


Best regards,
Yang