Re: [PATCH] KVM: X86: Call kvm_x86_ops.cpuid_update() after CPUIDs fully updated

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 5/28/2020 11:22 PM, Paolo Bonzini wrote:
> On 28/05/20 17:19, Xiaoyao Li wrote:
>> kvm_x86_ops.cpuid_update() is used to update vmx/svm settings based on
>> updated CPUID settings. So it's supposed to be called after CPUIDs are
>> fully updated, not in the middle stage.
>>
>> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> 
> Are you seeing anything bad happening from this?

Not yet.

IMO changing the order is more reasonable and less confusing.

> Paolo
> 
>> ---
>>   arch/x86/kvm/cpuid.c | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
>> index cd708b0b460a..753739bc1bf0 100644
>> --- a/arch/x86/kvm/cpuid.c
>> +++ b/arch/x86/kvm/cpuid.c
>> @@ -208,8 +208,11 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
>>   	vcpu->arch.cpuid_nent = cpuid->nent;
>>   	cpuid_fix_nx_cap(vcpu);
>>   	kvm_apic_set_version(vcpu);
>> -	kvm_x86_ops.cpuid_update(vcpu);
>>   	r = kvm_update_cpuid(vcpu);
>> +	if (r)
>> +		goto out;
>> +
>> +	kvm_x86_ops.cpuid_update(vcpu);
>>   
>>   out:
>>   	vfree(cpuid_entries);
>> @@ -231,8 +234,11 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
>>   		goto out;
>>   	vcpu->arch.cpuid_nent = cpuid->nent;
>>   	kvm_apic_set_version(vcpu);
>> -	kvm_x86_ops.cpuid_update(vcpu);
>>   	r = kvm_update_cpuid(vcpu);
>> +	if (r)
>> +		goto out;
>> +
>> +	kvm_x86_ops.cpuid_update(vcpu);
>>   out:
>>   	return r;
>>   }
>>
>