From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58633) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dsagi-0000eE-9x for qemu-devel@nongnu.org; Thu, 14 Sep 2017 16:24:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dsage-0004H6-WF for qemu-devel@nongnu.org; Thu, 14 Sep 2017 16:24:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32940) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dsage-0004Do-Ql for qemu-devel@nongnu.org; Thu, 14 Sep 2017 16:24:36 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BACDEC024B16 for ; Thu, 14 Sep 2017 20:24:35 +0000 (UTC) References: <1505420311-23744-1-git-send-email-mgamal@redhat.com> From: Thomas Huth Message-ID: <96709f6f-b4c8-f752-fd0d-f73de9023bcc@redhat.com> Date: Thu, 14 Sep 2017 22:24:23 +0200 MIME-Version: 1.0 In-Reply-To: <1505420311-23744-1-git-send-email-mgamal@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] amd_iommu: Return error on machines with no PCI List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mohammed Gamal , qemu-devel@nongnu.org Cc: pbonzini@redhat.com, ehabkost@redhat.com, mst@redhat.com On 14.09.2017 22:18, Mohammed Gamal wrote: > Starting the following command line causes a segfault > qemu-system-x86_64 -S -machine isapc,accel=kvm -device amd-iommu > > This is due to the fact that the machine type 'isapc' doesn't have > a PCI bus, while amd_iommu doesn't check if the machine has PCI support > and subsequently does a null-pointer access. AMD IOMMU shouldn't even work > if the target machine doesn't have PCI. > > Add a check for PCI on the given machine type and return an error if PCI > is not supported. > > Signed-off-by: Mohammed Gamal > --- > hw/i386/amd_iommu.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c > index 334938a..9a667b7 100644 > --- a/hw/i386/amd_iommu.c > +++ b/hw/i386/amd_iommu.c > @@ -1153,6 +1153,13 @@ static void amdvi_realize(DeviceState *dev, Error **err) > } > > bus = pcms->bus; > + > + if (!bus) { > + error_setg(err, "Machine-type '%s' does not support PCI", > + mc->name); > + return; > + } > + > s->iotlb = g_hash_table_new_full(amdvi_uint64_hash, > amdvi_uint64_equal, g_free, g_free); > > Patch looks fine to me, but I think it would also be sufficient to change the check at the beginning of the function to test "if (!pcms || !pcms->bus)" instead of just "if (!pcms)" ... the error message "Machine-type 'xxx' not supported by amd-iommu" is also adequate if there is no PCI bus available on the system. Thomas