On 6/7/2022 4:31 AM, Jim Mattson wrote: > On Thu, Jun 2, 2022 at 7:26 AM Santosh Shukla <santosh.shukla@xxxxxxx> wrote: >> >> Currently, NMI is delivered to the guest using the Event Injection >> mechanism [1]. The Event Injection mechanism does not block the delivery >> of subsequent NMIs. So the Hypervisor needs to track the NMI delivery >> and its completion(by intercepting IRET) before sending a new NMI. >> >> Virtual NMI (VNMI) allows the hypervisor to inject the NMI into the guest >> w/o using Event Injection mechanism meaning not required to track the >> guest NMI and intercepting the IRET. To achieve that, >> VNMI feature provides virtualized NMI and NMI_MASK capability bits in >> VMCB intr_control - >> V_NMI(11) - Indicates whether a virtual NMI is pending in the guest. >> V_NMI_MASK(12) - Indicates whether virtual NMI is masked in the guest. >> V_NMI_ENABLE(26) - Enables the NMI virtualization feature for the guest. >> >> When Hypervisor wants to inject NMI, it will set V_NMI bit, Processor will >> clear the V_NMI bit and Set the V_NMI_MASK which means the Guest is >> handling NMI, After the guest handled the NMI, The processor will clear >> the V_NMI_MASK on the successful completion of IRET instruction >> Or if VMEXIT occurs while delivering the virtual NMI. >> >> To enable the VNMI capability, Hypervisor need to program >> V_NMI_ENABLE bit 1. >> >> The presence of this feature is indicated via the CPUID function >> 0x8000000A_EDX[25]. >> >> Testing - >> * Used qemu's `inject_nmi` for testing. >> * tested with and w/o AVIC case. >> * tested with kvm-unit-test >> >> Thanks, >> Santosh >> [1] https://www.amd.com/system/files/TechDocs/40332.pdf >> ch-15.20 - "Event Injection". >> >> Santosh Shukla (7): >> x86/cpu: Add CPUID feature bit for VNMI >> KVM: SVM: Add VNMI bit definition >> KVM: SVM: Add VNMI support in get/set_nmi_mask >> KVM: SVM: Report NMI not allowed when Guest busy handling VNMI >> KVM: SVM: Add VNMI support in inject_nmi >> KVM: nSVM: implement nested VNMI >> KVM: SVM: Enable VNMI feature >> >> arch/x86/include/asm/cpufeatures.h | 1 + >> arch/x86/include/asm/svm.h | 7 +++++ >> arch/x86/kvm/svm/nested.c | 8 +++++ >> arch/x86/kvm/svm/svm.c | 47 ++++++++++++++++++++++++++++-- >> arch/x86/kvm/svm/svm.h | 1 + >> 5 files changed, 62 insertions(+), 2 deletions(-) >> >> -- >> 2.25.1 > > When will we see vNMI support in silicon? Genoa? > > Where is this feature officially documented? Is there an AMD64 > equivalent of the "Intel Architecture Instruction Set Extensions and > Future Features" manual? Hi Jim, A new revision of the Architecture programmers manual (APM) is slated to be release soon and that is going to have all the details for the above questions. Thanks, Santosh
