On 11/28/2024 8:39 PM, Manali Shukla wrote: > On 10/22/2024 11:18 AM, Manali Shukla wrote: >> The upcoming new Idle HLT Intercept feature allows for the HLT >> instruction execution by a vCPU to be intercepted by the hypervisor >> only if there are no pending V_INTR and V_NMI events for the vCPU. >> When the vCPU is expected to service the pending V_INTR and V_NMI >> events, the Idle HLT intercept won’t trigger. The feature allows the >> hypervisor to determine if the vCPU is actually idle and reduces >> wasteful VMEXITs. >> >> The idle HLT intercept feature is used for enlightened guests who wish >> to securely handle the events. When an enlightened guest does a HLT >> while an interrupt is pending, hypervisor will not have a way to >> figure out whether the guest needs to be re-entered or not. The Idle >> HLT intercept feature allows the HLT execution only if there are no >> pending V_INTR and V_NMI events. >> >> Presence of the Idle HLT Intercept feature is indicated via CPUID >> function Fn8000_000A_EDX[30]. >> >> Document for the Idle HLT intercept feature is available at [1]. >> >> This series is based on kvm-next/next (64dbb3a771a1) + [2]. >> >> Experiments done: >> ---------------- >> >> kvm_amd.avic is set to '0' for this experiment. >> >> The below numbers represent the average of 10 runs. >> >> Normal guest (L1) >> The below netperf command was run on the guest with smp = 1 (pinned). >> >> netperf -H <host ip> -t TCP_RR -l 60 >> ---------------------------------------------------------------- >> |with Idle HLT(transactions/Sec)|w/o Idle HLT(transactions/Sec)| >> ---------------------------------------------------------------- >> | 25645.7136 | 25773.2796 | >> ---------------------------------------------------------------- >> >> Number of transactions/sec with and without idle HLT intercept feature >> are almost same. >> >> Nested guest (L2) >> The below netperf command was run on L2 guest with smp = 1 (pinned). >> >> netperf -H <host ip> -t TCP_RR -l 60 >> ---------------------------------------------------------------- >> |with Idle HLT(transactions/Sec)|w/o Idle HLT(transactions/Sec)| >> ---------------------------------------------------------------- >> | 5655.4468 | 5755.2189 | >> ---------------------------------------------------------------- >> >> Number of transactions/sec with and without idle HLT intercept feature >> are almost same. >> >> Testing Done: >> - Tested the functionality for the Idle HLT intercept feature >> using selftest svm_idle_hlt_test. >> - Tested SEV and SEV-ES guest for the Idle HLT intercept functionality. >> - Tested the Idle HLT intercept functionality on nested guest. >> >> v3 -> v4 >> - Drop the patches to add vcpu_get_stat() into a new series [2]. >> - Added nested Idle HLT intercept support. >> >> v2 -> v3 >> - Incorporated Andrew's suggestion to structure vcpu_stat_types in >> a way that each architecture can share the generic types and also >> provide its own. >> >> v1 -> v2 >> - Done changes in svm_idle_hlt_test based on the review comments from Sean. >> - Added an enum based approach to get binary stats in vcpu_get_stat() which >> doesn't use string to get stat data based on the comments from Sean. >> - Added self_halt() and cli() helpers based on the comments from Sean. >> >> [1]: AMD64 Architecture Programmer's Manual Pub. 24593, April 2024, >> Vol 2, 15.9 Instruction Intercepts (Table 15-7: IDLE_HLT). >> https://bugzilla.kernel.org/attachment.cgi?id=306250 >> >> [2]: https://lore.kernel.org/kvm/20241021062226.108657-1-manali.shukla@xxxxxxx/T/#t >> >> Manali Shukla (4): >> x86/cpufeatures: Add CPUID feature bit for Idle HLT intercept >> KVM: SVM: Add Idle HLT intercept support >> KVM: nSVM: implement the nested idle halt intercept >> KVM: selftests: KVM: SVM: Add Idle HLT intercept test >> >> arch/x86/include/asm/cpufeatures.h | 1 + >> arch/x86/include/asm/svm.h | 1 + >> arch/x86/include/uapi/asm/svm.h | 2 + >> arch/x86/kvm/governed_features.h | 1 + >> arch/x86/kvm/svm/nested.c | 7 ++ >> arch/x86/kvm/svm/svm.c | 15 +++- >> tools/testing/selftests/kvm/Makefile | 1 + >> .../selftests/kvm/include/x86_64/processor.h | 1 + >> .../selftests/kvm/x86_64/svm_idle_hlt_test.c | 89 +++++++++++++++++++ >> 9 files changed, 115 insertions(+), 3 deletions(-) >> create mode 100644 tools/testing/selftests/kvm/x86_64/svm_idle_hlt_test.c >> >> >> base-commit: c8d430db8eec7d4fd13a6bea27b7086a54eda6da >> prerequisite-patch-id: ca912571db5c004f77b70843b8dd35517ff1267f >> prerequisite-patch-id: 164ea3b4346f9e04bc69819278d20f5e1b5df5ed >> prerequisite-patch-id: 90d870f426ebc2cec43c0dd89b701ee998385455 >> prerequisite-patch-id: 45812b799c517a4521782a1fdbcda881237e1eda > > A gentle reminder. > > -Manali A Gentle reminder. -Manali
