From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH] KVM: VMX: Update instruction length on intercepted BP Date: Sun, 14 Feb 2010 09:53:03 +0200 Message-ID: <20100214075303.GF2511@redhat.com> References: <4B767160.4070609@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Marcelo Tosatti , kvm To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:58253 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752402Ab0BNHxF (ORCPT ); Sun, 14 Feb 2010 02:53:05 -0500 Content-Disposition: inline In-Reply-To: <4B767160.4070609@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On Sat, Feb 13, 2010 at 10:31:12AM +0100, Jan Kiszka wrote: > From: Jan Kiszka > > We intercept #BP while in guest debugging mode. As VM exists due to > intercepted exceptions do not necessarily come with valid > idt_vectoring, we have to update event_exit_inst_len explicitly in such > cases. At least in the absence of migration, this ensures that > re-injections of #BP will find and use the correct instruction length. > event_exit_inst_len is only used for event reinjection. Since event intercepted here will not be reinjected why updating event_exit_inst_len is needed here? > Signed-off-by: Jan Kiszka > --- > > Please consider for stable, this fixes guest debugging scenarios. > > arch/x86/kvm/vmx.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index f82b072..e9f64e8 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -2775,6 +2775,8 @@ static int handle_rmode_exception(struct kvm_vcpu *vcpu, > kvm_queue_exception(vcpu, vec); > return 1; > case BP_VECTOR: > + to_vmx(vcpu)->vcpu.arch.event_exit_inst_len = > + vmcs_read32(VM_EXIT_INSTRUCTION_LEN); > if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) > return 0; > /* fall through */ > @@ -2897,6 +2899,8 @@ static int handle_exception(struct kvm_vcpu *vcpu) > kvm_run->debug.arch.dr7 = vmcs_readl(GUEST_DR7); > /* fall through */ > case BP_VECTOR: > + vmx->vcpu.arch.event_exit_inst_len = > + vmcs_read32(VM_EXIT_INSTRUCTION_LEN); > kvm_run->exit_reason = KVM_EXIT_DEBUG; > kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip; > kvm_run->debug.arch.exception = ex_no; > -- Gleb.