While initializing emulation context structure, kvm memsets to 0 a number of fields some of which are redundant since they get set eventually in x86_decode_insn. Cleanup unnecessary initializations and remove some fields. This is on top of Paolo's RFC KVM: x86: speedups for emulator memory accesses https://lkml.org/lkml/2014/4/1/494 Here are the new realmode.flat numbers with improvement wrt unpatched kernel - 639 cycles/emulated jump instruction (4.3%) 776 cycles/emulated move instruction (7.5%) 791 cycles/emulated arithmetic instruction (11%) 943 cycles/emulated memory load instruction (5.2%) 948 cycles/emulated memory store instruction (7.6%) 929 cycles/emulated memory RMW instruction (9.0%) v1 numbers - 639 cycles/emulated jump instruction 786 cycles/emulated move instruction 802 cycles/emulated arithmetic instruction 936 cycles/emulated memory load instruction 970 cycles/emulated memory store instruction 1000 cycles/emulated memory RMW instruction v2: All thanks and credit to Paolo! - 1/6 - no change - 2/6 - new patch, inercept and check_perm replaced with checks for bits in ctxt->d - 3/6 - new patch, remove if condition in decode_rm and rearrange bit operations - 4/6 - remove else conditions from v1 and misc cleanups - 5/6 - new patch, remove seg_override and related fields and functions - 6/6 - new patch, remove memopp and move rip_relative to a local variable in decode_modrm Bandan Das (6): KVM: emulate: move init_decode_cache to emulate.c KVM: emulate: Remove ctxt->intercept and ctxt->check_perm checks KVM: emulate: cleanup decode_rm KVM: emulate: clean up initializations in init_decode_cache KVM: emulate: rework seg_override KVM: emulate: remove memopp and rip_relative arch/x86/include/asm/kvm_emulate.h | 20 ++++----- arch/x86/kvm/emulate.c | 85 ++++++++++++++++++-------------------- arch/x86/kvm/x86.c | 13 ------ 3 files changed, 50 insertions(+), 68 deletions(-) -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
