Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753688Ab3FIKBx (ORCPT ); Sun, 9 Jun 2013 06:01:53 -0400 Received: from mail-ob0-f174.google.com ([209.85.214.174]:46745 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750889Ab3FIKBv (ORCPT ); Sun, 9 Jun 2013 06:01:51 -0400 Message-ID: <51B45289.6080704@gmail.com> Date: Sun, 09 Jun 2013 18:01:45 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Gleb Natapov CC: Paolo Bonzini , Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH] KVM: x86: fix missed memory synchronization when patch hypercall References: <51B2A1D9.6060306@gmail.com> <20130609084526.GH4725@redhat.com> <51B44B01.7050304@gmail.com> <20130609093910.GL4725@redhat.com> In-Reply-To: <20130609093910.GL4725@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2114 Lines: 58 On 06/09/2013 05:39 PM, Gleb Natapov wrote: > On Sun, Jun 09, 2013 at 05:29:37PM +0800, Xiao Guangrong wrote: >> On 06/09/2013 04:45 PM, Gleb Natapov wrote: >> >>> +static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt) >>> +{ >>> + struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt); >>> + return kvm_exec_with_stopped_vcpu(vcpu->kvm, >>> + emulator_fix_hypercall_cb, ctxt); >>> +} >>> + >>> + >>> /* >>> * Check if userspace requested an interrupt window, and that the >>> * interrupt window is open. >>> @@ -5761,6 +5769,10 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) >>> kvm_deliver_pmi(vcpu); >>> if (kvm_check_request(KVM_REQ_SCAN_IOAPIC, vcpu)) >>> vcpu_scan_ioapic(vcpu); >>> + if (kvm_check_request(KVM_REQ_STOP_VCPU, vcpu)){ >>> + mutex_lock(&vcpu->kvm->lock); >>> + mutex_unlock(&vcpu->kvm->lock); >> >> We should execute a serializing instruction here? >> >>> --- a/virt/kvm/kvm_main.c >>> +++ b/virt/kvm/kvm_main.c >>> @@ -222,6 +222,18 @@ void kvm_make_scan_ioapic_request(struct kvm *kvm) >>> make_all_cpus_request(kvm, KVM_REQ_SCAN_IOAPIC); >>> } >>> >>> +int kvm_exec_with_stopped_vcpu(struct kvm *kvm, int (*cb)(void *), void *data) >>> +{ >>> + int r; >>> + >>> + mutex_lock(&kvm->lock); >>> + make_all_cpus_request(kvm, KVM_REQ_STOP_VCPU); >>> + r = cb(data); >> >> And here? > Since the serialisation instruction the SDM suggest to use is CPUID I > think the point here is to flush CPU pipeline. Since all vcpus are out > of a guest mode I think out of order execution of modified instruction > is no an issue here. I checked the SDM that it did not said VMLAUNCH/VMRESUME are the serializing instructions both in VM-Entry description and Instruction reference, instead it said the VMX related serializing instructions are: INVEPT, INVVPID. So, i guess the explicit serializing instruction is needed here. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/