From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Nx10C-0002QX-Oz for qemu-devel@nongnu.org; Wed, 31 Mar 2010 12:42:48 -0400 Received: from [140.186.70.92] (port=39745 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Nx10B-0002O9-5c for qemu-devel@nongnu.org; Wed, 31 Mar 2010 12:42:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1Nx109-0004Z9-66 for qemu-devel@nongnu.org; Wed, 31 Mar 2010 12:42:47 -0400 Received: from mail-pw0-f45.google.com ([209.85.160.45]:56459) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1Nx108-0004UK-W5 for qemu-devel@nongnu.org; Wed, 31 Mar 2010 12:42:45 -0400 Received: by mail-pw0-f45.google.com with SMTP id 6so284502pwi.4 for ; Wed, 31 Mar 2010 09:42:44 -0700 (PDT) Message-ID: <4BB37B7F.7050006@codemonkey.ws> Date: Wed, 31 Mar 2010 11:42:39 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] [Also for STABLE-0.12] Don't check for bus master for old guests References: <1268763487-23446-1-git-send-email-agraf@suse.de> In-Reply-To: <1268763487-23446-1-git-send-email-agraf@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" On 03/16/2010 01:18 PM, Alexander Graf wrote: > Older Linux guests don't activate the bus master enable bit. So for those we > can just try to be clever and track if they set the DEVICE_OK bit even though > bus mastering is still disabled. > > Under that condition we can disable the windows safety check. With that logic > in place both guests should work just fine. Without PCI hotplug breaks > virtio-net in Linux< 2.6.34 guests. > > Signed-off-by: Alexander Graf > CC: Michael S. Tsirkin > Applied. Thanks. Regards, Anthony Liguori > --- > hw/virtio-pci.c | 25 ++++++++++++++++++++++++- > 1 files changed, 24 insertions(+), 1 deletions(-) > > diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c > index 3594152..4fc4b3c 100644 > --- a/hw/virtio-pci.c > +++ b/hw/virtio-pci.c > @@ -76,6 +76,10 @@ > * 12 is historical, and due to x86 page size. */ > #define VIRTIO_PCI_QUEUE_ADDR_SHIFT 12 > > +/* We can catch some guest bugs inside here so we continue supporting older > + guests. */ > +#define VIRTIO_PCI_BUG_BUS_MASTER (1<< 0) > + > /* QEMU doesn't strictly need write barriers since everything runs in > * lock-step. We'll leave the calls to wmb() in though to make it obvious for > * KVM or if kqemu gets SMP support. > @@ -87,6 +91,7 @@ > typedef struct { > PCIDevice pci_dev; > VirtIODevice *vdev; > + uint32_t bugs; > uint32_t addr; > uint32_t class_code; > uint32_t nvectors; > @@ -138,6 +143,13 @@ static int virtio_pci_load_config(void * opaque, QEMUFile *f) > if (proxy->vdev->config_vector != VIRTIO_NO_VECTOR) { > return msix_vector_use(&proxy->pci_dev, proxy->vdev->config_vector); > } > + > + /* Try to find out if the guest has bus master disabled, but is > + in ready state. Then we have a buggy guest OS. */ > + if (!(proxy->vdev->status& VIRTIO_CONFIG_S_DRIVER_OK)&& > + !(proxy->pci_dev.config[PCI_COMMAND]& PCI_COMMAND_MASTER)) { > + proxy->bugs |= VIRTIO_PCI_BUG_BUS_MASTER; > + } > return 0; > } > > @@ -162,6 +174,7 @@ static void virtio_pci_reset(DeviceState *d) > VirtIOPCIProxy *proxy = container_of(d, VirtIOPCIProxy, pci_dev.qdev); > virtio_reset(proxy->vdev); > msix_reset(&proxy->pci_dev); > + proxy->bugs = 0; > } > > static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val) > @@ -205,6 +218,14 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val) > virtio_reset(proxy->vdev); > msix_unuse_all_vectors(&proxy->pci_dev); > } > + > + /* Linux before 2.6.34 sets the device as OK without enabling > + the PCI device bus master bit. In this case we need to disable > + some safety checks. */ > + if ((val& VIRTIO_CONFIG_S_DRIVER_OK)&& > + !(proxy->pci_dev.config[PCI_COMMAND]& PCI_COMMAND_MASTER)) { > + proxy->bugs |= VIRTIO_PCI_BUG_BUS_MASTER; > + } > break; > case VIRTIO_MSI_CONFIG_VECTOR: > msix_vector_unuse(&proxy->pci_dev, vdev->config_vector); > @@ -372,7 +393,9 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address, > > if (PCI_COMMAND == address) { > if (!(val& PCI_COMMAND_MASTER)) { > - proxy->vdev->status&= ~VIRTIO_CONFIG_S_DRIVER_OK; > + if (!(proxy->bugs& VIRTIO_PCI_BUG_BUS_MASTER)) { > + proxy->vdev->status&= ~VIRTIO_CONFIG_S_DRIVER_OK; > + } > } > } > >