Messages in this thread | | | Subject | Re: [PATCH] KVM: x86: VMX: Make smaller physical guest address space support user-configurable | From | Paolo Bonzini <> | Date | Tue, 29 Sep 2020 14:26:13 +0200 |
| |
On 29/09/20 13:59, Qian Cai wrote: > > WARN_ON_ONCE(!allow_smaller_maxphyaddr); > > I noticed the origin patch did not have this WARN_ON_ONCE(), but the mainline > commit b96e6506c2ea ("KVM: x86: VMX: Make smaller physical guest address space > support user-configurable") does have it for some reasons.
Because that part of the code should not be reached. The exception bitmap is set up with
if (!vmx_need_pf_intercept(vcpu)) eb &= ~(1u << PF_VECTOR);
where
static inline bool vmx_need_pf_intercept(struct kvm_vcpu *vcpu) { if (!enable_ept) return true;
return allow_smaller_maxphyaddr && cpuid_maxphyaddr(vcpu) < boot_cpu_data.x86_phys_bits; }
We shouldn't get here if "enable_ept && !allow_smaller_maxphyaddr", which implies vmx_need_pf_intercept(vcpu) == false. So the warning is genuine; I've sent a patch.
Paolo
| |