From 41061cdb98a0bec464278b4db8e894a3121671f5 Mon Sep 17 00:00:00 2001 From: Bandan Das Date: Wed, 16 Apr 2014 12:46:14 -0400 Subject: [PATCH] KVM: emulate: do not initialize memopp rip_relative is only set if decode_modrm runs, and if you have ModRM you will also have a memopp. We can then access memopp unconditionally. Note that rip_relative cannot be hoisted up to decode_modrm, or you break "mov $0, xyz(%rip)". Also, move typecast on "out of range value" of mem.ea to decode_modrm. Together, all these optimizations save about 50 cycles on each emulated instructions (4-6%). Signed-off-by: Bandan Das [Fix immediate operands with rip-relative addressing. - Paolo] Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_emulate.h | 5 +++++ arch/x86/kvm/emulate.c | 8 ++++---- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h index 6c808408326f..fcf58cd25ebd 100644 --- a/arch/x86/include/asm/kvm_emulate.h +++ b/arch/x86/include/asm/kvm_emulate.h @@ -295,6 +295,11 @@ struct x86_emulate_ctxt { struct operand dst; int (*execute)(struct x86_emulate_ctxt *ctxt); int (*check_perm)(struct x86_emulate_ctxt *ctxt); + /* + * The following six fields are cleared together, + * the rest are initialized unconditionally in x86_decode_insn + * or elsewhere + */ bool rip_relative; u8 rex_prefix; u8 lock_prefix; diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 08badf638fb0..390400a54a9c 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1177,6 +1177,9 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt, } } op->addr.mem.ea = modrm_ea; + if (ctxt->ad_bytes != 8) + ctxt->memop.addr.mem.ea = (u32)ctxt->memop.addr.mem.ea; + done: return rc; } @@ -4425,9 +4428,6 @@ done_prefixes: ctxt->memop.addr.mem.seg = ctxt->seg_override; - if (ctxt->memop.type == OP_MEM && ctxt->ad_bytes != 8) - ctxt->memop.addr.mem.ea = (u32)ctxt->memop.addr.mem.ea; - /* * Decode and fetch the source operand: register, memory * or immediate. @@ -4448,7 +4448,7 @@ done_prefixes: rc = decode_operand(ctxt, &ctxt->dst, (ctxt->d >> DstShift) & OpMask); done: - if (ctxt->memopp && ctxt->memopp->type == OP_MEM && ctxt->rip_relative) + if (ctxt->rip_relative) ctxt->memopp->addr.mem.ea += ctxt->_eip; return (rc != X86EMUL_CONTINUE) ? EMULATION_FAILED : EMULATION_OK; -- 2.20.1