On Thu, Jun 20, 2019 at 4:02 AM Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote: > > Various intercepts hard-code the respective instruction lengths to optimize > skip_emulated_instruction(): when next_rip is pre-set we skip > kvm_emulate_instruction(vcpu, EMULTYPE_SKIP). The optimization is, however, > incorrect: different (redundant) prefixes could be used to enlarge the > instruction. We can't really avoid decoding. > > svm->next_rip is not used when CPU supports 'nrips' (X86_FEATURE_NRIPS) > feature: next RIP is provided in VMCB. The feature is not really new > (Opteron G3s had it already) and the change should have zero affect. > > Remove manual svm->next_rip setting with hard-coded instruction lengths. The > only case where we now use svm->next_rip is EXIT_IOIO: the instruction > length is provided to us by hardware. > > Reported-by: Jim Mattson <jmattson@xxxxxxxxxx> > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
