xref: /kvmtool/x86/cpuid.c (revision bc0b99a2a74047707db73ba057743febf458fd90)

#include "kvm/kvm-cpu.h"

#include "kvm/kvm.h"
#include "kvm/util.h"

#include <sys/ioctl.h>
#include <stdlib.h>

#define CPUID_FUNC_PERFMON		0x0A

#define	MAX_KVM_CPUID_ENTRIES		100

static void filter_cpuid(struct kvm_cpuid2 *kvm_cpuid)
{
	unsigned int signature[3];
	unsigned int i;

	/*
	 * Filter CPUID functions that are not supported by the hypervisor.
	 */
	for (i = 0; i < kvm_cpuid->nent; i++) {
		struct kvm_cpuid_entry2 *entry = &kvm_cpuid->entries[i];

		switch (entry->function) {
		case 0:
			/* Vendor name */
			memcpy(signature, "LKVMLKVMLKVM", 12);
			entry->ebx = signature[0];
			entry->ecx = signature[1];
			entry->edx = signature[2];
			break;
		case 1:
			/* Set X86_FEATURE_HYPERVISOR */
			if (entry->index == 0)
				entry->ecx |= (1 << 31);
			break;
		case 6:
			/* Clear X86_FEATURE_EPB */
			entry->ecx = entry->ecx & ~(1 << 3);
			break;
		case CPUID_FUNC_PERFMON:
			entry->eax = 0x00; /* disable it */
			break;
		default:
			/* Keep the CPUID function as -is */
			break;
		};
	}
}

void kvm_cpu__setup_cpuid(struct kvm_cpu *vcpu)
{
	struct kvm_cpuid2 *kvm_cpuid;

	kvm_cpuid = calloc(1, sizeof(*kvm_cpuid) +
				MAX_KVM_CPUID_ENTRIES * sizeof(*kvm_cpuid->entries));

	kvm_cpuid->nent = MAX_KVM_CPUID_ENTRIES;
	if (ioctl(vcpu->kvm->sys_fd, KVM_GET_SUPPORTED_CPUID, kvm_cpuid) < 0)
		die_perror("KVM_GET_SUPPORTED_CPUID failed");

	filter_cpuid(kvm_cpuid);

	if (ioctl(vcpu->vcpu_fd, KVM_SET_CPUID2, kvm_cpuid) < 0)
		die_perror("KVM_SET_CPUID2 failed");

	free(kvm_cpuid);
}