We can just blindly move all 16 bytes of ctxt->src's value to ctxt->dst. write_register_operand will take care of writing only the lower bytes.
Avoiding a call to memcpy (the compiler optimizes it out) gains about 200 cycles on kvm-unit-tests for register-to-register moves, and makes them about as fast as arithmetic instructions. We could perhaps get a larger speedup by moving all instructions _except_ moves out of x86_emulate_insn, removing opcode_len, and replacing the switch statement with an inlined em_mov. Signed-off-by: Paolo Bonzini <[email protected]> --- arch/x86/include/asm/kvm_emulate.h | 2 +- arch/x86/kvm/emulate.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h index ffa2671a7f2f..46725e8aa8cb 100644 --- a/arch/x86/include/asm/kvm_emulate.h +++ b/arch/x86/include/asm/kvm_emulate.h @@ -232,7 +232,7 @@ struct operand { union { unsigned long val; u64 val64; - char valptr[sizeof(unsigned long) + 2]; + char valptr[sizeof(sse128_t)]; sse128_t vec_val; u64 mm_val; void *data; diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 4c2ae824e89e..5f902d40740c 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2983,7 +2983,7 @@ static int em_rdpmc(struct x86_emulate_ctxt *ctxt) static int em_mov(struct x86_emulate_ctxt *ctxt) { - memcpy(ctxt->dst.valptr, ctxt->src.valptr, ctxt->op_bytes); + memcpy(ctxt->dst.valptr, ctxt->src.valptr, sizeof(ctxt->src.valptr)); return X86EMUL_CONTINUE; } -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
