From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] kvm:x86:Fix error handling in the function kvm_lapic_sync_to_vapic Date: Tue, 11 Aug 2015 15:13:35 +0200 Message-ID: <55C9F4FF.9090906@redhat.com> References: <1439234760-26445-1-git-send-email-xerofoify@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Nicholas Krause , gleb@kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:39700 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934136AbbHKNNr (ORCPT ); Tue, 11 Aug 2015 09:13:47 -0400 In-Reply-To: <1439234760-26445-1-git-send-email-xerofoify@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: On 10/08/2015 21:26, Nicholas Krause wrote: > This fixes error handling in the function kvm_lapic_sync_to_vapic > to check the value of the call to kvm_write_guest_cached to see if > it failed by returning a error code and if so execute WARN_ON to > allow the user to see in their logs the failure when executing the > function kvm_lapic_sync_to_vapic. > > Signed-off-by: Nicholas Krause > --- > arch/x86/kvm/lapic.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 2a5ca97..f3946c0 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1935,7 +1935,7 @@ static void apic_sync_pv_eoi_to_guest(struct kvm_vcpu *vcpu, > void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu) > { > u32 data, tpr; > - int max_irr, max_isr; > + int max_irr, max_isr, ret; > struct kvm_lapic *apic = vcpu->arch.apic; > > apic_sync_pv_eoi_to_guest(vcpu, apic); > @@ -1952,8 +1952,9 @@ void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu) > max_isr = 0; > data = (tpr & 0xff) | ((max_isr & 0xf0) << 8) | (max_irr << 24); > > - kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.apic->vapic_cache, &data, > - sizeof(u32)); > + ret = kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.apic->vapic_cache, &data, > + sizeof(u32)); > + WARN_ON(ret); > } > > int kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr) > It shouldn't happen, but I cannot rule out that a guest cannot trigger it. It would be a bug or bad behavior in the guest but, if it can, a WARN message in the host dmesg would not be the right thing to do. So I prefer to leave the return value unchecked. Paolo