linux-kernel - Re: [PATCH v2 11/14] KVM: SVM: Move SEV VMCB tracking allocation to sev.c

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Date:   Thu, 14 Jan 2021 15:53:53 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Brijesh Singh <brijesh.singh@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH v2 11/14] KVM: SVM: Move SEV VMCB tracking allocation to
 sev.c

On 1/14/21 3:37 PM, Brijesh Singh wrote:
> 
> On 1/13/21 6:37 PM, Sean Christopherson wrote:
>> Move the allocation of the SEV VMCB array to sev.c to help pave the way
>> toward encapsulating SEV enabling wholly within sev.c.
>>
>> No functional change intended.
>>
>> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
>> ---
>>   arch/x86/kvm/svm/sev.c | 13 +++++++++++++
>>   arch/x86/kvm/svm/svm.c | 17 ++++++++---------
>>   arch/x86/kvm/svm/svm.h |  1 +
>>   3 files changed, 22 insertions(+), 9 deletions(-)
>>
>> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
>> index 1a143340103e..a2c3e2d42a7f 100644
>> --- a/arch/x86/kvm/svm/sev.c
>> +++ b/arch/x86/kvm/svm/sev.c
>> @@ -1330,6 +1330,19 @@ void sev_hardware_teardown(void)
>>   	sev_flush_asids();
>>   }
>>   
>> +int sev_cpu_init(struct svm_cpu_data *sd)
>> +{
>> +	if (!svm_sev_enabled())
>> +		return 0;
>> +
>> +	sd->sev_vmcbs = kmalloc_array(max_sev_asid + 1, sizeof(void *),
>> +				      GFP_KERNEL | __GFP_ZERO);
> 
> 
> I saw Tom recommended to use kzalloc.. instead of __GFP_ZERO in previous

kcalloc :)

Thanks,
Tom

> patch. With that fixed,
> 
> Reviewed-by: Brijesh Singh <brijesh.singh@....com>
> 
> 
>> +	if (!sd->sev_vmcbs)
>> +		return -ENOMEM;
>> +
>> +	return 0;
>> +}
>> +
>>   /*
>>    * Pages used by hardware to hold guest encrypted state must be flushed before
>>    * returning them to the system.
>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>> index bb7b99743bea..89b95fb87a0c 100644
>> --- a/arch/x86/kvm/svm/svm.c
>> +++ b/arch/x86/kvm/svm/svm.c
>> @@ -552,23 +552,22 @@ static void svm_cpu_uninit(int cpu)
>>   static int svm_cpu_init(int cpu)
>>   {
>>   	struct svm_cpu_data *sd;
>> +	int ret;
>>   
>>   	sd = kzalloc(sizeof(struct svm_cpu_data), GFP_KERNEL);
>>   	if (!sd)
>>   		return -ENOMEM;
>>   	sd->cpu = cpu;
>>   	sd->save_area = alloc_page(GFP_KERNEL);
>> -	if (!sd->save_area)
>> +	if (!sd->save_area) {
>> +		ret = -ENOMEM;
>>   		goto free_cpu_data;
>> +	}
>>   	clear_page(page_address(sd->save_area));
>>   
>> -	if (svm_sev_enabled()) {
>> -		sd->sev_vmcbs = kmalloc_array(max_sev_asid + 1,
>> -					      sizeof(void *),
>> -					      GFP_KERNEL | __GFP_ZERO);
>> -		if (!sd->sev_vmcbs)
>> -			goto free_save_area;
>> -	}
>> +	ret = sev_cpu_init(sd);
>> +	if (ret)
>> +		goto free_save_area;
>>   
>>   	per_cpu(svm_data, cpu) = sd;
>>   
>> @@ -578,7 +577,7 @@ static int svm_cpu_init(int cpu)
>>   	__free_page(sd->save_area);
>>   free_cpu_data:
>>   	kfree(sd);
>> -	return -ENOMEM;
>> +	return ret;
>>   
>>   }
>>   
>> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
>> index 8e169835f52a..4eb4bab0ca3e 100644
>> --- a/arch/x86/kvm/svm/svm.h
>> +++ b/arch/x86/kvm/svm/svm.h
>> @@ -583,6 +583,7 @@ int svm_unregister_enc_region(struct kvm *kvm,
>>   void pre_sev_run(struct vcpu_svm *svm, int cpu);
>>   void __init sev_hardware_setup(void);
>>   void sev_hardware_teardown(void);
>> +int sev_cpu_init(struct svm_cpu_data *sd);
>>   void sev_free_vcpu(struct kvm_vcpu *vcpu);
>>   int sev_handle_vmgexit(struct vcpu_svm *svm);
>>   int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);