From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH 1/2] KVM: x86 emulator: don't update vcpu state if instruction is restarted. Date: Sun, 1 Aug 2010 12:01:45 +0300 Message-ID: <20100801090145.GD24773@redhat.com> References: <1280405513-579-1-git-send-email-gleb@redhat.com> <1280405513-579-2-git-send-email-gleb@redhat.com> <4C545C79.1010102@redhat.com> <20100801082815.GC24773@redhat.com> <4C55364E.9090605@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: mtosatti@redhat.com, kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:44210 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753250Ab0HAJBr (ORCPT ); Sun, 1 Aug 2010 05:01:47 -0400 Received: from int-mx03.intmail.prod.int.phx2.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o7191ktM023147 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sun, 1 Aug 2010 05:01:46 -0400 Content-Disposition: inline In-Reply-To: <4C55364E.9090605@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Sun, Aug 01, 2010 at 11:54:38AM +0300, Avi Kivity wrote: > On 08/01/2010 11:28 AM, Gleb Natapov wrote: > >On Sat, Jul 31, 2010 at 08:25:13PM +0300, Avi Kivity wrote: > >> On 07/29/2010 03:11 PM, Gleb Natapov wrote: > >>>No need to update vcpu state since instruction is in the middle of the > >>>emulation. > >>> > >>>Signed-off-by: Gleb Natapov > >>>--- > >>> arch/x86/kvm/x86.c | 31 +++++++++++++------------------ > >>> 1 files changed, 13 insertions(+), 18 deletions(-) > >>> > >>>diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > >>>index 76fbc32..7e5f075 100644 > >>>--- a/arch/x86/kvm/x86.c > >>>+++ b/arch/x86/kvm/x86.c > >>>@@ -4057,32 +4057,27 @@ restart: > >>> return handle_emulation_failure(vcpu); > >>> } > >>> > >>>- toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility); > >>>- kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags); > >>>- memcpy(vcpu->arch.regs, c->regs, sizeof c->regs); > >>>- kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip); > >>>+ r = EMULATE_DONE; > >>> > >>>- if (vcpu->arch.emulate_ctxt.exception>= 0) { > >>>+ if (vcpu->arch.emulate_ctxt.exception>= 0) > >>> inject_emulated_exception(vcpu); > >>>- return EMULATE_DONE; > >>>- } > >>>- > >>>- if (vcpu->arch.pio.count) { > >>>+ else if (vcpu->arch.pio.count) { > >>> if (!vcpu->arch.pio.in) > >>> vcpu->arch.pio.count = 0; > >>>- return EMULATE_DO_MMIO; > >>>- } > >>>- > >>>- if (vcpu->mmio_needed) { > >>>+ r = EMULATE_DO_MMIO; > >>>+ } else if (vcpu->mmio_needed) { > >>> if (vcpu->mmio_is_write) > >>> vcpu->mmio_needed = 0; > >>>- return EMULATE_DO_MMIO; > >>>- } > >>>- > >>>- if (vcpu->arch.emulate_ctxt.restart) > >>>+ r = EMULATE_DO_MMIO; > >>>+ } else if (vcpu->arch.emulate_ctxt.restart) > >>> goto restart; > >>> > >>>- return EMULATE_DONE; > >>>+ toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility); > >>>+ kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags); > >>>+ memcpy(vcpu->arch.regs, c->regs, sizeof c->regs); > >>>+ kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip); > >>>+ > >>>+ return r; > >>> } > >>> EXPORT_SYMBOL_GPL(emulate_instruction); > >>> > >>What about kvm-tpr-opt.c? It uses rip after pio. > >> > >It uses rip _during_ pio. And pio emulation changes rip > >only at the end of emulation. > > But non-emulated pio does a skip_emulated_instruction() immediately > (or so the code in kvm-tpr-opt.c assumes: > Indeed, this is bug in non-emulated pio. But the patch does not change rip behaviour for emulated pio. vcpu->arch.emulate_ctxt.eip is updated only at the end of emulation. > >static void vtpr_ioport_write(void *opaque, uint32_t addr, uint32_t val) > >{ > > CPUState *env = cpu_single_env; > > uint32_t rip; > > > > cpu_synchronize_state(env); > > > > rip = env->eip - 2; > > write_byte_virt(env, rip, 0x66); > > write_byte_virt(env, rip + 1, 0x90); > > ) > > -- > error compiling committee.c: too many arguments to function -- Gleb.