Re: [PATCH] pci/pci_expander_bridge: migrate state of pxb/pxb-pcie devices.

[Dr. David Alan Gilbert]

* Vladimir Sementsov-Ogievskiy (vsementsov@yandex-team.ru) wrote:
> [add migration maintainers]

Thanks,

> On 8/11/22 19:49, Andrey Ryabinin wrote:
> > pxb/pxb-pcie/pxb-cxl devices currently doesn't have vmstate description
> > So the state of device is not preserved during migration and
> > guest can notice that as change of PCI_COMMAND_* registers state.
> > 
> > The diff of lspci output before and after migration:
> > 
> >   00:03.0 Host bridge [0600]: Red Hat, Inc. QEMU PCIe Expander bridge 
> > [1b36:000b]
> >           Subsystem: Red Hat, Inc QEMU PCIe Expander bridge [1af4:1100]
> >   -       Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- 
> > ParErr- Stepping- SERR+ FastB2B- DisINTx-
> >   +       Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- 
> > ParErr- Stepping- SERR- FastB2B- DisINTx-
> >           Status: Cap- 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- 
> > <TAbort- <MAbort- >SERR- <PERR- INTx-

Do you notice any other symptoms other than that minor diff?

> > Add VMStateDescription to pxb devices so their state is transferred
> > during migrations. For saving migration compatibility add
> > 'x-config-reg-migration-enabled' property to pxb devices and disable
> > it for all released machine types.
> > 
> > Signed-off-by: Andrey Ryabinin <arbn@yandex-team.com>
> > ---
> >   hw/core/machine.c                   |  3 +++
> >   hw/pci-bridge/pci_expander_bridge.c | 24 ++++++++++++++++++++++++
> >   include/hw/pci/pci_bridge.h         |  1 +
> >   3 files changed, 28 insertions(+)
> > 
> > diff --git a/hw/core/machine.c b/hw/core/machine.c
> > index a673302ccec..071853469e2 100644
> > --- a/hw/core/machine.c
> > +++ b/hw/core/machine.c
> > @@ -43,6 +43,9 @@
> >   GlobalProperty hw_compat_7_0[] = {
> >       { "arm-gicv3-common", "force-8-bit-prio", "on" },
> >       { "nvme-ns", "eui64-default", "on"},
> > +    { "pxb", "x-config-reg-migration-enabled", "off" },
> > +    { "pxb-cxl", "x-config-reg-migration-enabled", "off" },
> > +    { "pxb-pcie", "x-config-reg-migration-enabled", "off" },
> 
> 
> Seems that it's too late for 7.1, rc2 is out and rc3 is coming soon. And 
> that's not a degradation.

Yeh

> Up to maintainers, but I think we'd better start new hw_compat_7_1 for this 
> thing.

Yep.


Dave
> 
> >   };
> >   const size_t hw_compat_7_0_len = G_N_ELEMENTS(hw_compat_7_0);
> > diff --git a/hw/pci-bridge/pci_expander_bridge.c 
> > b/hw/pci-bridge/pci_expander_bridge.c
> > index c9e817aa586..a3680d4d045 100644
> > --- a/hw/pci-bridge/pci_expander_bridge.c
> > +++ b/hw/pci-bridge/pci_expander_bridge.c
> > @@ -23,6 +23,7 @@
> >   #include "qemu/error-report.h"
> >   #include "qemu/module.h"
> >   #include "sysemu/numa.h"
> > +#include "migration/vmstate.h"
> >   #include "hw/boards.h"
> >   #include "qom/object.h"
> > @@ -404,9 +405,29 @@ static Property pxb_dev_properties[] = {
> >       DEFINE_PROP_UINT8("bus_nr", PXBDev, bus_nr, 0),
> >       DEFINE_PROP_UINT16("numa_node", PXBDev, numa_node, 
> > NUMA_NODE_UNASSIGNED),
> >       DEFINE_PROP_BOOL("bypass_iommu", PXBDev, bypass_iommu, false),
> > +    DEFINE_PROP_BOOL("x-config-reg-migration-enabled", PXBDev,
> > +                     migratable, true),
> 
> With it, do we create a user-visible property? If so, is it possible to avoid 
> it?
> 
> >       DEFINE_PROP_END_OF_LIST(),
> >   };
> > +static bool pxb_vmstate_needed(void *opaque)
> > +{
> > +    PXBDev *pxb = opaque;
> > +
> > +    return pxb->migratable;
> > +}
> > +
> > +static const VMStateDescription vmstate_pxb_device = {
> > +    .name = "pxb-pci",
> > +    .needed = pxb_vmstate_needed,
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_PCI_DEVICE(parent_obj, PXBDev),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> >   static void pxb_dev_class_init(ObjectClass *klass, void *data)
> >   {
> >       DeviceClass *dc = DEVICE_CLASS(klass);
> > @@ -422,6 +443,7 @@ static void pxb_dev_class_init(ObjectClass *klass, void 
> > *data)
> >       device_class_set_props(dc, pxb_dev_properties);
> >       dc->hotpluggable = false;
> >       set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
> > +    dc->vmsd = &vmstate_pxb_device;
> >   }
> >   static const TypeInfo pxb_dev_info = {
> > @@ -460,6 +482,7 @@ static void pxb_pcie_dev_class_init(ObjectClass *klass, 
> > void *data)
> >       device_class_set_props(dc, pxb_dev_properties);
> >       dc->hotpluggable = false;
> >       set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
> > +    dc->vmsd = &vmstate_pxb_device;
> >   }
> >   static const TypeInfo pxb_pcie_dev_info = {
> > @@ -504,6 +527,7 @@ static void pxb_cxl_dev_class_init(ObjectClass *klass, 
> > void *data)
> >       /* Host bridges aren't hotpluggable. FIXME: spec reference */
> >       dc->hotpluggable = false;
> >       dc->reset = pxb_dev_reset;
> > +    dc->vmsd = &vmstate_pxb_device;
> >   }
> >   static const TypeInfo pxb_cxl_dev_info = {
> > diff --git a/include/hw/pci/pci_bridge.h b/include/hw/pci/pci_bridge.h
> > index ba4bafac7c2..404dc02e36e 100644
> > --- a/include/hw/pci/pci_bridge.h
> > +++ b/include/hw/pci/pci_bridge.h
> > @@ -91,6 +91,7 @@ struct PXBDev {
> >       uint8_t bus_nr;
> >       uint16_t numa_node;
> >       bool bypass_iommu;
> > +    bool migratable;
> >       struct cxl_dev {
> >           CXLHost *cxl_host_bridge; /* Pointer to a CXLHost */
> >       } cxl;
> 
> 
> -- 
> Best regards,
> Vladimir
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK