Messages in this thread Patch in this message | | | From | Paolo Bonzini <> | Subject | [PATCH 18/25] KVM: emulate: do not initialize memopp | Date | Mon, 9 Jun 2014 14:59:06 +0200 |
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From: Bandan Das <bsd@redhat.com>
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 <bsd@redhat.com> [Fix immediate operands with rip-relative addressing. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- 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 268bbd4aae99..692b0bfadf91 100644 --- a/arch/x86/include/asm/kvm_emulate.h +++ b/arch/x86/include/asm/kvm_emulate.h @@ -322,6 +322,11 @@ 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 05f7bb416fc2..32f38a3467a0 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1176,6 +1176,9 @@ 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; } @@ -4499,9 +4502,6 @@ 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. @@ -4522,7 +4522,7 @@ 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; -- 1.8.3.1
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