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SubjectRe: [PATCH v3 1/2] KVM: nVMX: enhance allocate/free_vpid to handle shadow vpid
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On 9/16/15 2:42 PM, Jan Kiszka wrote:
> On 2015-09-16 05:51, Wanpeng Li wrote:
>> Enhance allocate/free_vid to handle shadow vpid.
>>
>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
>> ---
>> arch/x86/kvm/vmx.c | 24 +++++++++++-------------
>> 1 file changed, 11 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 9ff6a3f..4956081 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -4155,29 +4155,27 @@ static int alloc_identity_pagetable(struct kvm *kvm)
>> return r;
>> }
>>
>> -static void allocate_vpid(struct vcpu_vmx *vmx)
>> +static int allocate_vpid(void)
>> {
>> - int vpid;
>> + int vpid = 0;
> Initialization is not pointless with the current code.
>
>>
>> - vmx->vpid = 0;
>> if (!enable_vpid)
>> - return;
>> + return 0;
>> spin_lock(&vmx_vpid_lock);
>> vpid = find_first_zero_bit(vmx_vpid_bitmap, VMX_NR_VPIDS);
>> - if (vpid < VMX_NR_VPIDS) {
>> - vmx->vpid = vpid;
>> + if (vpid < VMX_NR_VPIDS)
>> __set_bit(vpid, vmx_vpid_bitmap);
>> - }
>> spin_unlock(&vmx_vpid_lock);
>> + return vpid;
> You should return 0 also if vpid == VMX_NR_VPIDS.

Agreed.

>
>> }
>>
>> -static void free_vpid(struct vcpu_vmx *vmx)
>> +static void free_vpid(int vpid)
>> {
>> if (!enable_vpid)
> You could already test for vpid == 0 here...
>
>> return;
>> spin_lock(&vmx_vpid_lock);
>> - if (vmx->vpid != 0)
>> - __clear_bit(vmx->vpid, vmx_vpid_bitmap);
>> + if (vpid != 0)
> ...then you could skip this.

Agreed.

>
>> + __clear_bit(vpid, vmx_vpid_bitmap);
>> spin_unlock(&vmx_vpid_lock);
>> }
>>
>> @@ -8482,7 +8480,7 @@ static void vmx_free_vcpu(struct kvm_vcpu *vcpu)
>>
>> if (enable_pml)
>> vmx_disable_pml(vmx);
>> - free_vpid(vmx);
>> + free_vpid(vmx->vpid);
>> leave_guest_mode(vcpu);
>> vmx_load_vmcs01(vcpu);
>> free_nested(vmx);
>> @@ -8501,7 +8499,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
>> if (!vmx)
>> return ERR_PTR(-ENOMEM);
>>
>> - allocate_vpid(vmx);
>> + vmx->vpid = allocate_vpid();
>>
>> err = kvm_vcpu_init(&vmx->vcpu, kvm, id);
>> if (err)
>> @@ -8577,7 +8575,7 @@ free_msrs:
>> uninit_vcpu:
>> kvm_vcpu_uninit(&vmx->vcpu);
>> free_vcpu:
>> - free_vpid(vmx);
>> + free_vpid(vmx->vpid);
>> kmem_cache_free(kvm_vcpu_cache, vmx);
>> return ERR_PTR(err);
>> }
>>
> Yes, this is what I had in mind.

Thanks for your review. :-)

Regards,
Wanpeng Li


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