Commit 45363e46 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

Revert "virtio-pci: fix migration for pci bus master" 



This reverts commit 4d43d3f3.

Reported to break PPC guests.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 8ce3c44c

hw/virtio/virtio-pci.c

+19 −20
Original line number Diff line number Diff line
@@ -86,6 +86,9 @@ 
 * 12 is historical, and due to x86 page size. */

#define VIRTIO_PCI_QUEUE_ADDR_SHIFT    12



/* Flags track per-device state like workarounds for quirks in older guests. */

#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG  (1 << 0)



static void virtio_pci_bus_new(VirtioBusState *bus, size_t bus_size,

                               VirtIOPCIProxy *dev);
@@ -320,6 +323,14 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val) 
                                     proxy->pci_dev.config[PCI_COMMAND] |

                                     PCI_COMMAND_MASTER, 1);

        }



        /* 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->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG;

        }

        break;

    case VIRTIO_MSI_CONFIG_VECTOR:

        msix_vector_unuse(&proxy->pci_dev, vdev->config_vector);
@@ -469,18 +480,13 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address, 
    VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);

    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);



    uint8_t cmd = proxy->pci_dev.config[PCI_COMMAND];



    pci_default_write_config(pci_dev, address, val, len);



    if (range_covers_byte(address, len, PCI_COMMAND) &&

        !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER) &&

        (cmd & PCI_COMMAND_MASTER)) {

        /* Bus driver disables bus mastering - make it act

         * as a kind of reset to render the device quiescent. */

        !(proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG)) {

        virtio_pci_stop_ioeventfd(proxy);

        virtio_reset(vdev);

        msix_unuse_all_vectors(&proxy->pci_dev);

        virtio_set_status(vdev, vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK);

    }

}
@@ -889,19 +895,11 @@ static void virtio_pci_vmstate_change(DeviceState *d, bool running) 
    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);



    if (running) {

        /* Linux before 2.6.34 drives the device without enabling

           the PCI device bus master bit. Enable it automatically

           for the guest. This is a PCI spec violation but so is

           initiating DMA with bus master bit clear.

           Note: this only makes a difference when migrating

           across QEMU versions from an old QEMU, as for new QEMU

           bus master and driver bits are always in sync.

           TODO: consider enabling conditionally for compat machine types. */

        if (vdev->status & (VIRTIO_CONFIG_S_ACKNOWLEDGE |

                            VIRTIO_CONFIG_S_DRIVER)) {

            pci_default_write_config(&proxy->pci_dev, PCI_COMMAND,

                                     proxy->pci_dev.config[PCI_COMMAND] |

                                     PCI_COMMAND_MASTER, 1);

        /* Try to find out if the guest has bus master disabled, but is

           in ready state. Then we have a buggy guest OS. */

        if ((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 {
@@ -1042,6 +1040,7 @@ static void virtio_pci_reset(DeviceState *qdev) 
    virtio_pci_stop_ioeventfd(proxy);

    virtio_bus_reset(bus);

    msix_unuse_all_vectors(&proxy->pci_dev);

    proxy->flags &= ~VIRTIO_PCI_FLAG_BUS_MASTER_BUG;

}



static Property virtio_pci_properties[] = {