On 12/12/2024 10:07 PM, Manali Shukla wrote: > 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 > A Gentle reminder. -Manali
