https://bugzilla.kernel.org/show_bug.cgi?id=82211
--- Comment #1 from Zhou, Chao <chao.z...@intel.com> ---
the first bad commit is:
commit 6addfc42992be4b073c39137ecfdf4b2aa2d487f
Author: Paolo Bonzini <pbonz...@redhat.com>
Date: Thu Mar 27 11:29:28 2014 +0100
KVM: x86: avoid useless set of KVM_REQ_EVENT after emulation
Despite the provisions to emulate up to 130 consecutive instructions, in
practice KVM will emulate just one before exiting
handle_invalid_guest_state
because x86_emulate_instruction always sets KVM_REQ_EVENT.
However, we only need to do this if an interrupt could be injected,
which happens a) if an interrupt shadow bit (STI or MOV SS) has gone
away; b) if the interrupt flag has just been set (other instructions
than STI can set it without enabling an interrupt shadow).
This cuts another 700-900 cycles from the cost of emulating an
instruction (measured on a Sandy Bridge Xeon: 1650-2600 cycles
before the patch on kvm-unit-tests, 925-1700 afterwards).
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
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