From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59880) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TRpyc-0000nb-Th for qemu-devel@nongnu.org; Fri, 26 Oct 2012 15:53:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TRpyb-0007mV-Ry for qemu-devel@nongnu.org; Fri, 26 Oct 2012 15:53:54 -0400 Received: from mail-ee0-f45.google.com ([74.125.83.45]:64902) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TRpyb-0007m9-L3 for qemu-devel@nongnu.org; Fri, 26 Oct 2012 15:53:53 -0400 Received: by mail-ee0-f45.google.com with SMTP id b47so1329101eek.4 for ; Fri, 26 Oct 2012 12:53:52 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <508AEA4E.5080202@redhat.com> Date: Fri, 26 Oct 2012 21:53:50 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1351272088-7942-1-git-send-email-aliguori@us.ibm.com> <1351272088-7942-3-git-send-email-aliguori@us.ibm.com> <508ADDAA.7070205@redhat.com> In-Reply-To: <508ADDAA.7070205@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/4] virtio-rng-pci: create a default backend if none exists List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Amit Shah , qemu-devel@nongnu.org, Andreas Faerber Il 26/10/2012 20:59, Paolo Bonzini ha scritto: > Il 26/10/2012 19:21, Anthony Liguori ha scritto: >> This allows you to specify: >> >> $ qemu -device virtio-rng-pci >> >> And things will Just Work with a reasonable default. >> >> Signed-off-by: Anthony Liguori >> --- >> hw/virtio-pci.c | 13 +++++++++++++ >> hw/virtio-rng.h | 2 ++ >> 2 files changed, 15 insertions(+) >> >> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c >> index 0dc2a06..cfdb779 100644 >> --- a/hw/virtio-pci.c >> +++ b/hw/virtio-pci.c >> @@ -885,6 +885,19 @@ static int virtio_rng_init_pci(PCIDevice *pci_dev) >> VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev); >> VirtIODevice *vdev; >> >> + if (proxy->rng.rng == NULL) { >> + proxy->rng.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM)); >> + >> + object_property_add_child(OBJECT(pci_dev), >> + "default-backend", >> + OBJECT(proxy->rng.default_backend), >> + NULL); >> + >> + object_property_set_link(OBJECT(pci_dev), >> + OBJECT(proxy->rng.default_backend), >> + "rng", NULL); >> + } >> + >> vdev = virtio_rng_init(&pci_dev->qdev, &proxy->rng); >> if (!vdev) { >> return -1; >> diff --git a/hw/virtio-rng.h b/hw/virtio-rng.h >> index fbb0104..63ddb96 100644 >> --- a/hw/virtio-rng.h >> +++ b/hw/virtio-rng.h >> @@ -13,12 +13,14 @@ >> #define _QEMU_VIRTIO_RNG_H >> >> #include "qemu/rng.h" >> +#include "qemu/rng-random.h" >> >> /* The Virtio ID for the virtio rng device */ >> #define VIRTIO_ID_RNG 4 >> >> struct VirtIORNGConf { >> RngBackend *rng; >> + RndRandom *default_backend; >> }; >> >> #endif >> > > NACK. Starting a guest that runs rngd (or just a malicious guest) will > completely deprive the host of entropy. > > If you make the default /dev/hwrng, however, that would be ok. Also, does this break non-Linux? What if the default was changed to /dev/hwrng but an older Linux distro didn't have the device file at all? Paolo