Patchwork [master,stable] virtio-pci: fix bus master work around on load

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Submitter Michael S. Tsirkin
Date March 19, 2011, 10:30 p.m.
Message ID <20110319223004.GA6323@redhat.com>
Download mbox | patch
Permalink /patch/87639/
State New
Headers show

Comments

Michael S. Tsirkin - March 19, 2011, 10:30 p.m.
Commit c81131db15dd1844d0db1d51f3cd7a105cfd2cf3
detects old guests by comparing virtio and
PCI status. It attempts to do this on load,
as well, but load_config callback in a binding
is invoked too early and so the virtio status
isn't set yet.

We could add yet another callback to the
binding, to invoke after load, but it
seems easier to reuse the existing vmstate
callback.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Alexander Graf <agraf@suse.de>
---
 hw/virtio-pci.c |   13 ++++++-------
 hw/virtio.h     |    1 +
 2 files changed, 7 insertions(+), 7 deletions(-)
Alexander Graf - March 21, 2011, 12:33 p.m.
On 19.03.2011, at 23:30, Michael S. Tsirkin wrote:

> Commit c81131db15dd1844d0db1d51f3cd7a105cfd2cf3
> detects old guests by comparing virtio and
> PCI status. It attempts to do this on load,
> as well, but load_config callback in a binding
> is invoked too early and so the virtio status
> isn't set yet.
> 
> We could add yet another callback to the
> binding, to invoke after load, but it
> seems easier to reuse the existing vmstate
> callback.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Cc: Alexander Graf <agraf@suse.de>

Looks good to me. I assume you have tested the code by running an old guest?


Alex

Patch

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 3911b09..d40ac23 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -160,13 +160,6 @@  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->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG;
-    }
     return 0;
 }
 
@@ -651,6 +644,12 @@  static void virtio_pci_vmstate_change(void *opaque, bool running)
     VirtIOPCIProxy *proxy = opaque;
 
     if (running) {
+        /* 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->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG;
+        }
         virtio_pci_start_ioeventfd(proxy);
     } else {
         virtio_pci_stop_ioeventfd(proxy);