On 17 Jul 2017, at 19:59 PM, Michael S. Tsirkin <m...@redhat.com> wrote:
>
> On Mon, Jul 17, 2017 at 03:48:03PM +0300, Dmitry Fleytman wrote:
>> Am I understand correctly that there are no special cases for
>> IDE controllers, i.e. bus master bit must be set by SW same
>> way as for other PCI devices?
>
> Bus mastering is typically enabled by the driver.
> E.g. under linux:
>
> static int virtio_pci_restore(struct device *dev)
> {
> struct pci_dev *pci_dev = to_pci_dev(dev);
> struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> int ret;
>
> ret = pci_enable_device(pci_dev);
> if (ret)
> return ret;
>
> pci_set_master(pci_dev);
> return virtio_device_restore(&vp_dev->vdev);
> }
>
>
> As an exception, in case of BIOS booting using device ROM, it is set by
> the ROM. E.g. src/hw/virtio-pci.c:
>
> vp_reset(vp);
> pci_enable_busmaster(pci);
> vp_set_status(vp, VIRTIO_CONFIG_S_ACKNOWLEDGE |
> VIRTIO_CONFIG_S_DRIVER );
Thanks, Michael.
After some more investigations, there are additional interesting details.
First of all, resume from hibernation succeeds without USB host controller
(-usbtablet).
I did tracing of PCI configuration space writes and here is what I see:
========= Booting with -usbtablet (piix3-usb-uhci) ================
++ pci_init_bus_master:93: i440FX, enabled: 0
++ pci_init_bus_master:93: PIIX3, enabled: 0
++ pci_init_bus_master:93: piix3-ide, enabled: 0
++ pci_init_bus_master:93: piix3-usb-uhci, enabled: 0
++ pci_init_bus_master:93: PIIX4_PM, enabled: 0
++ pci_init_bus_master:93: VGA, enabled: 0
++ pci_init_bus_master:93: e1000, enabled: 0
All devices start with bus master disabled
++ piix3_reset:121
++ pci_default_write_config:1363: i440FX, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: PIIX3, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 259, l 2, enabled: 0
Guest writes 259 (2 bytes) to PCI_COMMAND, i.e. PCI_COMMAND_IO |
PCI_COMMAND_MEMORY | PCI_COMMAND_SERR.
This way it effectively disables PCI_COMMAND_MASTER event if it was enabled
from the beginning.
++ pci_default_write_config:1363: piix3-usb-uhci, addr 4, val_in 259, l 2,
enabled: 0
++ pci_default_write_config:1363: PIIX4_PM, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: VGA, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: e1000, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: piix3-usb-uhci, addr 4, val_in 259, l 2,
enabled: 0
++ pci_default_write_config:1363: piix3-usb-uhci, addr 4, val_in 263, l 2,
enabled: 4
At the same time it enables PCI_COMMAND_MASTER for piix3-usb-uhci.
After that it does a bunch of sector reads without DMA and then switches to DMA
mode and eventually crashes
========= Booting without -usbtablet (piix3-usb-uhci) ================
++ pci_init_bus_master:93: i440FX, enabled: 0
++ pci_init_bus_master:93: PIIX3, enabled: 0
++ pci_init_bus_master:93: piix3-ide, enabled: 0
++ pci_init_bus_master:93: PIIX4_PM, enabled: 0
++ pci_init_bus_master:93: VGA, enabled: 0
++ pci_init_bus_master:93: e1000, enabled: 0
All devices start with bus master disabled
++ piix3_reset:121
++ pci_default_write_config:1363: i440FX, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: PIIX3, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: PIIX4_PM, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: VGA, addr 4, val_in 259, l 2, enabled: 0
++ pci_default_write_config:1363: e1000, addr 4, val_in 259, l 2, enabled: 0
Again it writes 259 to PCI_COMMAND
After that it does a bunch of sector reads without DMA as before.
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 1285, l 2, enabled:
4
And after that it enables PCI bus master on piix3-ide,
starts DMA transfers and SUCEEDS resume from hibernation
++ pci_default_write_config:1363: VGA, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: VGA, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: VGA, addr 4, val_in 1287, l 2, enabled: 4
++ pci_default_write_config:1363: e1000, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: e1000, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: e1000, addr 4, val_in 1287, l 2, enabled: 4
++ pci_default_write_config:1363: e1000, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: e1000, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: e1000, addr 4, val_in 1287, l 2, enabled: 4
++ pci_default_write_config:1363: e1000, addr 4, val_in 1287, l 2, enabled: 4
++ pci_default_write_config:1363: e1000, addr 4, val_in 263, l 2, enabled: 4
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 1280, l 2, enabled: 0
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 1285, l 2, enabled:
4
++ pci_default_write_config:1363: piix3-ide, addr 4, val_in 261, l 2, enabled: 4
It also enables bus master for all other devices at some point.
Do you have any idea for possible directions?
Regards,
Dmitry
>
>
> --
> MST
