linux-kernel - Re: [PATCH 1/3] KVM: VMX: introduce alloc_loaded

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Date:   Tue, 16 Jan 2018 18:38:19 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     David Hildenbrand <david@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH 1/3] KVM: VMX: introduce alloc_loaded_vmcs

On 16/01/2018 18:27, David Hildenbrand wrote:
> On 16.01.2018 17:52, Paolo Bonzini wrote:
>> Group together the calls to alloc_vmcs and loaded_vmcs_init.  Soon we'll also
>> allocate an MSR bitmap there.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
>> ---
>>  arch/x86/kvm/vmx.c | 36 ++++++++++++++++++++++--------------
>>  1 file changed, 22 insertions(+), 14 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 00d76292a5d2..d81fd4a87f2b 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -3799,11 +3799,6 @@ static struct vmcs *alloc_vmcs_cpu(int cpu)
>>  	return vmcs;
>>  }
>>  
>> -static struct vmcs *alloc_vmcs(void)
>> -{
>> -	return alloc_vmcs_cpu(raw_smp_processor_id());
>> -}
>> -
>>  static void free_vmcs(struct vmcs *vmcs)
>>  {
>>  	free_pages((unsigned long)vmcs, vmcs_config.order);
>> @@ -3835,6 +3830,22 @@ static void vmx_nested_free_vmcs02(struct vcpu_vmx *vmx)
>>  	free_loaded_vmcs(loaded_vmcs);
>>  }
>>  
>> +static struct vmcs *alloc_vmcs(void)
>> +{
>> +	return alloc_vmcs_cpu(raw_smp_processor_id());
>> +}
>> +
> 
> don't understand why that was moved :)

Because later alloc_loaded_vmcs needs to call free_loaded_vmcs so I
wanted to put all free before alloc. :)

>> +static int alloc_loaded_vmcs(struct loaded_vmcs *loaded_vmcs)
> 
> maybe s/alloc_/init_/ would be a better name?
> 
>> +{
>> +	loaded_vmcs->vmcs = alloc_vmcs();
>> +	if (!loaded_vmcs->vmcs)
>> +		return -ENOMEM;
>> +
>> +	loaded_vmcs->shadow_vmcs = NULL;
>> +	loaded_vmcs_init(loaded_vmcs);
>> +	return 0;
>> +}
>> +
>>  static void free_kvm_area(void)
>>  {
>>  	int cpu;
>> @@ -7168,12 +7179,11 @@ static int enter_vmx_operation(struct kvm_vcpu *vcpu)
>>  {
>>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
>>  	struct vmcs *shadow_vmcs;
>> +	int r;
>>  
>> -	vmx->nested.vmcs02.vmcs = alloc_vmcs();
>> -	vmx->nested.vmcs02.shadow_vmcs = NULL;
>> -	if (!vmx->nested.vmcs02.vmcs)
>> +	r = alloc_loaded_vmcs(&vmx->nested.vmcs02);
>> +	if (r < 0)
>>  		goto out_vmcs02;
> 
> local variable r is not needed
> 
> if (alloc_ ...)

Yes, but it's less readable.

Paolo