@@ -669,6 +669,10 @@ MSRs that have been set successfully.
Defines the vcpu responses to the cpuid instruction. Applications
should use the KVM_SET_CPUID2 ioctl if available.
+Note, when this IOCTL fails, KVM gives no guarantees that previous valid CPUID
+configuration (if there is) is not corrupted. Userspace can get a copy of valid
+CPUID configuration through KVM_GET_CPUID2 in case.
+
::
struct kvm_cpuid_entry {
@@ -207,6 +207,8 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
kvm_apic_set_version(vcpu);
kvm_x86_ops.cpuid_update(vcpu);
r = kvm_update_cpuid(vcpu);
+ if (r)
+ vcpu->arch.cpuid_nent = 0;
kvfree(cpuid_entries);
out:
@@ -230,6 +232,8 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
kvm_apic_set_version(vcpu);
kvm_x86_ops.cpuid_update(vcpu);
r = kvm_update_cpuid(vcpu);
+ if (r)
+ vcpu->arch.cpuid_nent = 0;
out:
return r;
}
Current implementation keeps userspace input of CPUID configuration and cpuid->nent even if kvm_update_cpuid() fails. Reset vcpu->arch.cpuid_nent to 0 for the case of failure as a simple fix. Besides, update the doc to explicitly state that if IOCTL SET_CPUID* fail KVM gives no gurantee that previous valid CPUID configuration is kept. Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com> --- Documentation/virt/kvm/api.rst | 4 ++++ arch/x86/kvm/cpuid.c | 4 ++++ 2 files changed, 8 insertions(+)