From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51713) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZICvg-0002P7-3y for qemu-devel@nongnu.org; Thu, 23 Jul 2015 05:36:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZICve-0001Dv-63 for qemu-devel@nongnu.org; Thu, 23 Jul 2015 05:36:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55687) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZICve-0001Dn-0H for qemu-devel@nongnu.org; Thu, 23 Jul 2015 05:36:38 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id 911BC32555F for ; Thu, 23 Jul 2015 09:36:37 +0000 (UTC) Message-ID: <55B09F15.1030808@redhat.com> Date: Thu, 23 Jul 2015 16:00:21 +0800 From: Jason Wang MIME-Version: 1.0 References: <1437559884-13532-1-git-send-email-mst@redhat.com> In-Reply-To: <1437559884-13532-1-git-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] virtio: hide legacy features from modern guests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" , qemu-devel@nongnu.org On 07/22/2015 06:11 PM, Michael S. Tsirkin wrote: > NOTIFY_ON_EMPTY, ANY_LAYOUT and BAD are only valid on the legacy > interface. > > Hide them from modern guests. > > Signed-off-by: Michael S. Tsirkin Should we do the same for device specific legacy feature bits? > --- > include/hw/virtio/virtio.h | 4 ++++ > hw/virtio/virtio-pci.c | 3 ++- > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > index fbb3c06..cbe3a5a 100644 > --- a/include/hw/virtio/virtio.h > +++ b/include/hw/virtio/virtio.h > @@ -25,6 +25,10 @@ > /* A guest should never accept this. It implies negotiation is broken. */ > #define VIRTIO_F_BAD_FEATURE 30 > > +#define VIRTIO_LEGACY_FEATURES ((0x1ULL << VIRTIO_F_BAD_FEATURE) | \ > + (0x1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | \ > + (0x1ULL << VIRTIO_F_ANY_LAYOUT)) > + > struct VirtQueue; > > static inline hwaddr vring_align(hwaddr addr, > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index 283401a..db8f27c 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -1095,7 +1095,8 @@ static uint64_t virtio_pci_common_read(void *opaque, hwaddr addr, > break; > case VIRTIO_PCI_COMMON_DF: > if (proxy->dfselect <= 1) { > - val = vdev->host_features >> (32 * proxy->dfselect); > + val = (vdev->host_features & ~VIRTIO_LEGACY_FEATURES) >> > + (32 * proxy->dfselect); > } > break; > case VIRTIO_PCI_COMMON_GFSELECT: