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SubjectRe: [PATCH v2 2/4] KVM: x86: Partially allow KVM_SET_CPUID{,2} after KVM_RUN
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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:

/* 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 *orig;
int i;

if (nent != vcpu->arch.cpuid_nent)
return -EINVAL;

for (i = 0; i < nent; i++) {
orig = &vcpu->arch.cpuid_entries[i];
if (e2[i].function != orig->function ||
e2[i].index != orig->index ||
e2[i].eax != orig->eax || e2[i].ebx != orig->ebx ||
e2[i].ecx != orig->ecx || e2[i].edx != orig->edx)
return -EINVAL;
}

return 0;
}

avoiding the repeated calls to kvm_find_cpuid_entry?

Paolo

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