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

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This reverts commit 4d43d3f3c8.

Reported to break PPC guests.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2014-09-29 11:27:32 +03:00
parent 8ce3c44c92
commit 45363e46ae
1 changed files with 19 additions and 20 deletions
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39
hw/virtio/virtio-pci.c
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@ -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[] = {