Il 16/04/2014 18:46, Bandan Das ha scritto:
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
v3:
Minor changes as proposed in review
- 3/6 - cleanup typos
- 6/6 - change comment in struct x86_emulate_ctxt and add back a missing
if in decode_modrm
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_modrm
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 | 26 +++++++-----
arch/x86/kvm/emulate.c | 85 ++++++++++++++++++--------------------
arch/x86/kvm/x86.c | 13 ------
3 files changed, 56 insertions(+), 68 deletions(-)
Applied to a private branch collecting all the emulator speedups. Thanks!
Paolo
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