From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx> There are some issues with respect to nSVM L1 -> L2 event injection. First, the next_rip field of a VMCB is *not* an output-only field for a VMRUN. This field value (instead of the saved guest RIP) in used by the CPU for the return address pushed on stack when injecting a software interrupt or INT3 or INTO exception (this was confirmed by AMD). On a VMRUN that does event injection it has similar function as VMX's VM_ENTRY_INSTRUCTION_LEN field, although, in contrast to VMX, it holds an absolute RIP value, not a relative increment. However, KVM seems to treat this field as a unidirectional hint from the CPU to the hypervisor - there seems to be no specific effort to maintain this field consistency for such VMRUN. This is mostly visible with running a nested guest, with L1 trying to inject an event into its L2. In this case, we need to make sure the next_rip field gets synced from vmcb12 to vmcb02. Another issue is that pending L1 -> L2 events are forgotten if there is an intervening L0 VMEXIT during their delivery. We need to make sure they are remembered (including their desired next_rip field value) until they are either re-injected into L2 successfully or returned back to L1 in the EXITINTINFO field upon a nested VMEXIT. A new KVM self-test that checks for the nSVM issues described above is included in this patch series. These issues are SVM-specific - all the use cases described above already work correctly with VMX. This patch set was tested with both Linux and Windows nested guests. KVM: nSVM: Sync next_rip field from vmcb12 to vmcb02 KVM: SVM: Downgrade BUG_ON() to WARN_ON() in svm_inject_irq() KVM: nSVM: Don't forget about L1-injected events KVM: nSVM: Restore next_rip when doing L1 -> L2 event re-injection KVM: selftests: nSVM: Add svm_nested_soft_inject_test arch/x86/kvm/svm/nested.c | 69 +++++++- arch/x86/kvm/svm/svm.c | 60 ++++++- arch/x86/kvm/svm/svm.h | 48 ++++++ tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/include/x86_64/svm_util.h | 2 + .../kvm/x86_64/svm_nested_soft_inject_test.c | 147 ++++++++++++++++++ 7 files changed, 324 insertions(+), 4 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
