[PULL,11/26] pci-bridge/i82801b11: clear bridge registers on platform reset

From: Laszlo Ersek <lersek@redhat.com>

The "i82801b11-bridge" device model is a descendant of "base-pci-bridge"
(TYPE_PCI_BRIDGE). However, unlike other similar devices, such as

- pci-bridge,
- pcie-pci-bridge,
- PCIE Root Port,
- xio3130 switch upstream and downstream ports,
- dec-21154-p2p-bridge,
- pbm-bridge,
- xilinx-pcie-root,

"i82801b11-bridge" does not clear the bridge specific registers at
platform reset.

This is a problem because devices on "i82801b11-bridge" continue to
respond to config space cycles after platform reset, when addressed with
the bus number that was previously programmed into the secondary bus
number register of "i82801b11-bridge". This error breaks OVMF's search for
extra (PXB) root buses, for example.

The device class reset method for "i82801b11-bridge" is currently NULL;
set it directly to pci_bridge_reset(), like the last three bridge models
in the above listing do.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Marcel Apfelbaum <marcel@redhat.com>
Cc: qemu-stable@nongnu.org
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1541839
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/pci-bridge/i82801b11.c | 1 +
 1 file changed, 1 insertion(+)

Michael, Peter,

On 02/08/18 20:09, Michael S. Tsirkin wrote:
> From: Laszlo Ersek <lersek@redhat.com>
> 
> The "i82801b11-bridge" device model is a descendant of "base-pci-bridge"
> (TYPE_PCI_BRIDGE). However, unlike other similar devices, such as
> 
> - pci-bridge,
> - pcie-pci-bridge,
> - PCIE Root Port,
> - xio3130 switch upstream and downstream ports,
> - dec-21154-p2p-bridge,
> - pbm-bridge,
> - xilinx-pcie-root,
> 
> "i82801b11-bridge" does not clear the bridge specific registers at
> platform reset.
> 
> This is a problem because devices on "i82801b11-bridge" continue to
> respond to config space cycles after platform reset, when addressed with
> the bus number that was previously programmed into the secondary bus
> number register of "i82801b11-bridge". This error breaks OVMF's search for
> extra (PXB) root buses, for example.
> 
> The device class reset method for "i82801b11-bridge" is currently NULL;
> set it directly to pci_bridge_reset(), like the last three bridge models
> in the above listing do.
> 
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Marcel Apfelbaum <marcel@redhat.com>
> Cc: qemu-stable@nongnu.org
> Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1541839
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/pci-bridge/i82801b11.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/pci-bridge/i82801b11.c b/hw/pci-bridge/i82801b11.c
> index cb522bf..ebf7f5f 100644
> --- a/hw/pci-bridge/i82801b11.c
> +++ b/hw/pci-bridge/i82801b11.c
> @@ -98,6 +98,7 @@ static void i82801b11_bridge_class_init(ObjectClass *klass, void *data)
>      k->realize = i82801b11_bridge_realize;
>      k->config_write = pci_bridge_write_config;
>      dc->vmsd = &i82801b11_bridge_dev_vmstate;
> +    dc->reset = pci_bridge_reset;
>      set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
>  }
>  
> 

this patch didn't get included in the 2.11.1 round-up:

http://mid.mail-archive.com/20180206191515.25830-1-mdroth@linux.vnet.ibm.com

(The patch was posted, CC stable, between Mike's round-up set and the
actual 2.11.1 release.)

Can we please make sure that the commit doesn't miss the 2.11.2 bus?
2.12 is still a month out, and without this patch, rebooting an UEFI
guest OS (with OVMF) hangs, on certain VM configs (see the commit message).

(Apologies if there is a "queue" or "next" branch for stable releases --
in that case I should have probably checked that branch before sending
this email.)

The commit hash on the master branch is
ed247f40db84c8bd4bb7d10948702cd47cc4d5ae; it's part of v2.12.0-rc0.

Thanks!
Laszlo

Quoting Laszlo Ersek (2018-03-23 13:42:07)
> Michael, Peter,
> 
> On 02/08/18 20:09, Michael S. Tsirkin wrote:
> > From: Laszlo Ersek <lersek@redhat.com>
> > 
> > The "i82801b11-bridge" device model is a descendant of "base-pci-bridge"
> > (TYPE_PCI_BRIDGE). However, unlike other similar devices, such as
> > 
> > - pci-bridge,
> > - pcie-pci-bridge,
> > - PCIE Root Port,
> > - xio3130 switch upstream and downstream ports,
> > - dec-21154-p2p-bridge,
> > - pbm-bridge,
> > - xilinx-pcie-root,
> > 
> > "i82801b11-bridge" does not clear the bridge specific registers at
> > platform reset.
> > 
> > This is a problem because devices on "i82801b11-bridge" continue to
> > respond to config space cycles after platform reset, when addressed with
> > the bus number that was previously programmed into the secondary bus
> > number register of "i82801b11-bridge". This error breaks OVMF's search for
> > extra (PXB) root buses, for example.
> > 
> > The device class reset method for "i82801b11-bridge" is currently NULL;
> > set it directly to pci_bridge_reset(), like the last three bridge models
> > in the above listing do.
> > 
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Cc: Marcel Apfelbaum <marcel@redhat.com>
> > Cc: qemu-stable@nongnu.org
> > Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1541839
> > Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> > Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  hw/pci-bridge/i82801b11.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/hw/pci-bridge/i82801b11.c b/hw/pci-bridge/i82801b11.c
> > index cb522bf..ebf7f5f 100644
> > --- a/hw/pci-bridge/i82801b11.c
> > +++ b/hw/pci-bridge/i82801b11.c
> > @@ -98,6 +98,7 @@ static void i82801b11_bridge_class_init(ObjectClass *klass, void *data)
> >      k->realize = i82801b11_bridge_realize;
> >      k->config_write = pci_bridge_write_config;
> >      dc->vmsd = &i82801b11_bridge_dev_vmstate;
> > +    dc->reset = pci_bridge_reset;
> >      set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
> >  }
> >  
> > 
> 
> this patch didn't get included in the 2.11.1 round-up:
> 
> http://mid.mail-archive.com/20180206191515.25830-1-mdroth@linux.vnet.ibm.com
> 
> (The patch was posted, CC stable, between Mike's round-up set and the
> actual 2.11.1 release.)

Looks like I had it tagged as pending but the PULL got held up for a while
and it didn't hit master till the day before release. I'm okay with
cherry-picking from a maintainer tree but generally only do it if I get
poked about it or it's on my radar for other reasons.

> 
> Can we please make sure that the commit doesn't miss the 2.11.2 bus?
> 2.12 is still a month out, and without this patch, rebooting an UEFI
> guest OS (with OVMF) hangs, on certain VM configs (see the commit message).
> 
> (Apologies if there is a "queue" or "next" branch for stable releases --
> in that case I should have probably checked that branch before sending
> this email.)

There's https://github.com/mdroth/qemu/commits/stable-2.11-staging but
as you can see it generally doesn't see much action in-between releases.

Will start queueing patches for 2.11.2 soon and make sure it gets in,
but probably looking at a similar release timeframe as 2.12.

Thanks for the heads up!

> 
> The commit hash on the master branch is
> ed247f40db84c8bd4bb7d10948702cd47cc4d5ae; it's part of v2.12.0-rc0.
> 
> Thanks!
> Laszlo
>