On Wed, 10 Dec 2014 19:13:59 +0200
"Michael S. Tsirkin" <m...@redhat.com> wrote:
> On Wed, Dec 10, 2014 at 05:45:58PM +0100, Igor Mammedov wrote:
> > On Wed, 10 Dec 2014 18:24:24 +0200
> > "Michael S. Tsirkin" <m...@redhat.com> wrote:
> >
> > > On Wed, Dec 10, 2014 at 04:06:56PM +0000, Igor Mammedov wrote:
> > > > linker and RSDP tables are build only once, so if later
> > > > during rebuild sizes of other ACPI tables change
> > > > pointers will be patched incorrectly due to wrong
> > > > offsets.
> > > >
> > > > To fix it rebuild linker and RSDP tables along with
> > > > the rest of ACPI tables so that they would have correct
> > > > offsets.
> > > >
> > > > Here is a simple reproducer:
> > > > 1: hotplug bridge using command:
> > > > device_add pci-bridge,chassis_nr=1
> > > > 2: reset system from monitor:
> > > > system_reset
> > > >
> > > > As result pointers to ACPI tables are not correct
> > > > and guest can't read/parse ACPI tables.
> > > > Windows guests just refuse to boot and
> > > > Linux guests are more resilient and try to boot without
> > > > ACPI, sometimes successfully.
> > > >
> > > > PS:
> > > > keep brokenness in 2.2 and older machine types for the sake
> > > > of migration
> > > >
> > > > Signed-off-by: Igor Mammedov <imamm...@redhat.com>
> > >
> > > I'd like to fix 2.2 as well.
> > that's easy,
> > has_imutable_rsdp = true
> > should be moved into
> > pc_compat_2_1()
> >
> > >
> > > Why does adding bridge in this way cause tables to
> > > be resized?
> > > I think this is a root-cause that should be fixed.
> > That's because there wasn't any bridge described in tables
> > on startup, but after hotplug and reset tables are rebuild
> > which pickups hotplugged bridge and its secondary PCI bus.
> >
> > This behavior seems sane, I'd expect bare-metal behave
> > the same way.
>
> For a simple fix, we can skip bridges added by hotplug -
> treat them as regular devices.
>
> It defintely seems nicer - at least for old machine types -
> than "keep brokenness".
>
> I think the following should do the trcik, but it's completely
> untested.
> Could you pls try?
>
>
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index b37a397..039776d 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -844,7 +844,8 @@ static void build_pci_bus_end(PCIBus *bus, void
> *bus_state)
> * Skip bridge subtree creation if bridge hotplug is disabled
> * to make acpi tables compatible with legacy machine types.
> */
> - if (!child->pcihp_bridge_en && bus->parent_dev) {
> + if (bus->parent_dev && (!child->pcihp_bridge_en ||
> + !DEVICE(bus->parent_dev)->hotplugged)) {
> return;
> }
What will happen if
hotplug may bridges in
QEMU-fixed^^ -M 2.1
migrate to target:
QEMU-2.1 -M 2.1 + hotplugged on sourcebridges on CLI
My guess it may fail due to ACPI blob size difference.
