Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes:
> Paolo Bonzini <pbonzini@xxxxxxxxxx> writes:
>
>> On 1/17/22 16:05, Vitaly Kuznetsov wrote:
>>>
>>> +/* Check whether the supplied CPUID data is equal to what is already set for the vCPU. */
>>> +static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
>>> + int nent)
>>> +{
>>> + struct kvm_cpuid_entry2 *best;
>>> + int i;
>>> +
>>> + for (i = 0; i < nent; i++) {
>>> + best = kvm_find_cpuid_entry(vcpu, e2[i].function, e2[i].index);
>>> + if (!best)
>>> + return -EINVAL;
>>> +
>>> + if (e2[i].eax != best->eax || e2[i].ebx != best->ebx ||
>>> + e2[i].ecx != best->ecx || e2[i].edx != best->edx)
>>> + return -EINVAL;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>
>> What about this alternative implementation:
>>
...
>>
>> avoiding the repeated calls to kvm_find_cpuid_entry?
>>
>
> My version is a bit more permissive as it allows supplying CPUID entries
> in any order, not necessarily matching the original. I *guess* this
> doesn't matter much for the QEMU problem we're trying to workaround,
> I'll have to check.
I tried this with QEMU and nothing blew up, during CPU hotplug entries
come in the same order as the original. v3 which I've just sent
implements this suggestion.
--
Vitaly
