[PATCH v2 0/5] KVM: x86: Implement Pause Loop Exit for SVM

From: Babu Moger
Date: Fri Mar 16 2018 - 16:38:01 EST


This series adds PLE(pause loop exit) logic from VMX to SVM.

We have noticed considerable reduction in number of VMEXITS due to pause
interceptions after these changes. Here are the numbers on one guest with
32 vcpus on AMD EPYC system. We have used boot parameter idle=poll to
simulate extensive pauses on the guest.

Here are VMEXITS in 10 seconds interval.

#VMEXITS(in 10s) Before the change After the change
Pauses 810199 504
Total 882184 325415

v2:
Handled most of the Radim's comments. Here are the changes.
1. Fixed the module parameters to unsigned variants
1. Kept the default pause_filter_count = 3000 for AMD.
2. Removed the ple_window_actual_max parameter. Added a check
in __grow_ple_window to avoid overflow.
3. Fixed the naming conventions for SVM module parameters.
They are now called as pause_filter_count, pause_filter_thresh,
pause_filter_shrink and pause_filter_grow.
4. Taken care of intercept setting and clearing.
5. Fixed few more text changes.

v1:
Initial RFC version

Babu Moger (5):
KVM: VMX: Fix the module parameters for vmx
KVM: VMX: Remove ple_window_actual_max
KVM: VMX: Bring the common code to header file
KVM: SVM: Add pause filter threshold
KVM: SVM: Implement pause loop exit logic in SVM

arch/x86/include/asm/svm.h | 3 +-
arch/x86/kvm/svm.c | 108 ++++++++++++++++++++++++++++++++++++++++++++-
arch/x86/kvm/vmx.c | 82 +++++++---------------------------
arch/x86/kvm/x86.h | 37 ++++++++++++++++
4 files changed, 161 insertions(+), 69 deletions(-)

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1.8.3.1