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authorPaolo Bonzini <pbonzini@redhat.com>2014-03-27 11:36:25 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2014-07-11 09:13:58 +0200
commit54cfdb3e95d4f70409a7d3432a42cffc9a232be7 (patch)
tree01ad8c40d9c316b7359fb7e7605ba0c9b85a75eb /arch/x86/kvm
parentd40a6898e50c2589ca3d345ef5ca6671e2b35b1a (diff)
downloadlinux-54cfdb3e95d4f70409a7d3432a42cffc9a232be7.tar.gz
KVM: emulate: speed up emulated moves
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 <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/emulate.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index ea56dae3e67..27f677ef703 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2990,7 +2990,7 @@ 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;
}