On 04/10/2017 15:17, Brijesh Singh wrote: > + /* > + * On AMD platforms, under certain conditions insn_len may be zero on #NPF. > + * This can happen if a guest gets a page-fault on data access but the HW > + * table walker is not able to read the instruction page (e.g instruction > + * page is not present in memory). > + * > + * Typically, when insn_len is zero, x86_emulate_instruction() walks the > + * guest page table and fetches the instruction bytes from guest memory. > + * When SEV is enabled, the guest memory is encrypted with guest-specific > + * key hence hypervisor will not able to fetch the instruction bytes. > + * In those cases we simply restart the guest. > + */ > + if (unlikely(!insn_len) && > + kvm_x86_ops->mem_enc_enabled && > + kvm_x86_ops->mem_enc_enabled(vcpu)) > + return 1; > + Is it needed to test mem_enc_enabled? Could it instead test for the availability of decode assists? Thanks, Paolo
