On 25/11/2016 15:51, Radim Krčmář wrote: > The guest could have configured a maximal physical address that exceeds > the host. Prevent that situation as it could easily lead to a bug. > > Signed-off-by: Radim Krčmář <[email protected]> > --- > arch/x86/kvm/cpuid.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 25f0f15fab1a..aed910e9fbed 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -136,7 +136,13 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > ((best->eax & 0xff00) >> 8) != 0) > return -EINVAL; > > - /* Update physical-address width */ > + > + /* > + * Update physical-address width. > + * Make sure that it does not exceed hardware capabilities. > + */ > + if (cpuid_query_maxphyaddr(vcpu) > boot_cpu_data.x86_phys_bits) > + return -EINVAL; > vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu); > > kvm_pmu_refresh(vcpu); >
Not possible unfortunately, this would break most versions of QEMU that hard-code 40 for MAXPHYADDR. Also, "wider" physical addresses in the guest are actually possible with shadow paging. Paolo
