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charset="us-ascii" On Thu, Oct 10, 2024, Pankaj Gupta wrote: > On 10/9/2024 5:04 PM, Sean Christopherson wrote: > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index db567d26f7b9..450dd0444a92 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -969,6 +969,15 @@ static inline struct kvm_io_bus *kvm_get_bus(struct kvm *kvm, enum kvm_bus idx) > > static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i) > > { > > int num_vcpus = atomic_read(&kvm->online_vcpus); > > + > > + /* > > + * Explicitly verify the target vCPU is online, as the anti-speculation > > + * logic only limits the CPU's ability to speculate, e.g. given a "bad" > > + * index, clamping the index to 0 would return vCPU0, not NULL. > > + */ > > + if (i >= num_vcpus) > > + return NULL; > > Would sev.c needs a NULL check for? > > sev_migrate_from() > ... > src_vcpu = kvm_get_vcpu(src_kvm, i); > src_svm = to_svm(src_vcpu); > ... Nope, sev_check_source_vcpus() verifies the source and destination have the same number of online vCPUs before calling sev_migrate_from(), and it's all done with both VMs locked. static int sev_check_source_vcpus(struct kvm *dst, struct kvm *src) { struct kvm_vcpu *src_vcpu; unsigned long i; if (!sev_es_guest(src)) return 0; if (atomic_read(&src->online_vcpus) != atomic_read(&dst->online_vcpus)) return -EINVAL; kvm_for_each_vcpu(i, src_vcpu, src) { if (!src_vcpu->arch.guest_state_protected) return -EINVAL; } return 0; }