From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:56364) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gqmCa-0001Ml-Lc for qemu-devel@nongnu.org; Mon, 04 Feb 2019 16:54:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gqmCY-0000b9-ML for qemu-devel@nongnu.org; Mon, 04 Feb 2019 16:54:52 -0500 References: <20190130155733.32742-1-david@redhat.com> <20190130155733.32742-4-david@redhat.com> <80dae41f-f3f0-1acd-1fd6-8e7473712802@linux.ibm.com> From: David Hildenbrand Message-ID: <5c81b64a-7de0-210f-adb9-bf7f1ad10622@redhat.com> Date: Mon, 4 Feb 2019 22:54:40 +0100 MIME-Version: 1.0 In-Reply-To: <80dae41f-f3f0-1acd-1fd6-8e7473712802@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [qemu-s390x] [PATCH v2 3/6] s390x/pci: Warn when adding PCI devices without the 'zpci' feature List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Collin Walling , qemu-devel@nongnu.org Cc: Thomas Huth , Pierre Morel , Cornelia Huck , Christian Borntraeger , qemu-s390x@nongnu.org, Richard Henderson On 04.02.19 21:19, Collin Walling wrote: > On 1/30/19 10:57 AM, David Hildenbrand wrote: >> We decided to always create the PCI host bridge, even if 'zpci' is not >> enabled (due to migration compatibility). This however right now allows >> to add zPCI/PCI devices to a VM although the guest will never actually see >> them, confusing people that are using a simple CPU model that has no >> 'zpci' enabled - "Why isn't this working" (David Hildenbrand) >> >> Let's check for 'zpci' and at least print a warning that this will not >> work as expected. We could also bail out, however that might break >> existing QEMU commandlines. >> >> Reviewed-by: Thomas Huth >> Signed-off-by: David Hildenbrand >> --- >> hw/s390x/s390-pci-bus.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c >> index 9b5c5fff60..2efd9186c2 100644 >> --- a/hw/s390x/s390-pci-bus.c >> +++ b/hw/s390x/s390-pci-bus.c >> @@ -826,6 +826,11 @@ static void s390_pcihost_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev, >> { >> S390pciState *s = S390_PCI_HOST_BRIDGE(hotplug_dev); >> >> + if (!s390_has_feat(S390_FEAT_ZPCI)) { >> + warn_report("PCI/zPCI device without the 'zpci' CPU feature." >> + " The guest will not be able to see/use this device"); >> + } >> + >> if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) { >> PCIDevice *pdev = PCI_DEVICE(dev); >> >> > > I wonder if someone might misconstrue this as "the _PCI device_ needs > the zpci feature." I think "'zpci' CPU feature required to support > PCI/zPCI devices." reads better. The last sentence is fine to me. > Well, the guest needs the 'zpci' feature to see the device. And that's what that message says in my opinion. Not that a device needs to have a feature (I added "CPU feature" for this reason). "required to support" does it not make very clear what we actually want to say. Thanks! -- Thanks, David / dhildenb