Re: [PATCH] Introduce global piix flag to disable PCI hotplug

[Ani Sinha <ani@anisinha.ca>]

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On Mon, Aug 10, 2020 at 8:17 PM Michael S. Tsirkin <mst@redhat.com> wrote:

> On Mon, Aug 10, 2020 at 04:59:41PM +0530, Ani Sinha wrote:
> > We introduce a new global flag for PIIX with which we can
> > turn on or off PCI device hotplug. This flag can be used
> > to prevent all PCI devices from getting hotplugged/unplugged
> > on the PCI bus. The new options disables all hotpluh HW
> > initialization code as well as the ACPI AMLs.
> >
> > Signed-off-by: Ani Sinha <ani@anisinha.ca>
>
> Well we have a flag like this for pci bridges, right?
> So all that's left is an option to disable hotplug
> for the pci root, right?
> Wouldn't that be better than disabling it globally?


The idea is to have just one option to disable all hotplug globally. But if
you want to have two flags one for the bridges and one for the pci root, we
can certainly look into it.


>
> > ---
> >  hw/acpi/piix4.c      |  8 ++++++--
> >  hw/i386/acpi-build.c | 20 ++++++++++++++------
> >  2 files changed, 20 insertions(+), 8 deletions(-)
> >
> > diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
> > index 26bac4f..8b13e86 100644
> > --- a/hw/acpi/piix4.c
> > +++ b/hw/acpi/piix4.c
> > @@ -78,6 +78,7 @@ typedef struct PIIX4PMState {
> >
> >      AcpiPciHpState acpi_pci_hotplug;
> >      bool use_acpi_hotplug_bridge;
> > +    bool use_acpi_pci_hotplug;
> >
> >      uint8_t disable_s3;
> >      uint8_t disable_s4;
> > @@ -595,8 +596,9 @@ static void
> piix4_acpi_system_hot_add_init(MemoryRegion *parent,
> >                            "acpi-gpe0", GPE_LEN);
> >      memory_region_add_subregion(parent, GPE_BASE, &s->io_gpe);
> >
> > -    acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent,
> > -                    s->use_acpi_hotplug_bridge);
> > +    if (s->use_acpi_pci_hotplug)
> > +        acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent,
> > +                        s->use_acpi_hotplug_bridge);
> >
> >      s->cpu_hotplug_legacy = true;
> >      object_property_add_bool(OBJECT(s), "cpu-hotplug-legacy",
> > @@ -635,6 +637,8 @@ static Property piix4_pm_properties[] = {
> >      DEFINE_PROP_UINT8(ACPI_PM_PROP_S4_VAL, PIIX4PMState, s4_val, 2),
> >      DEFINE_PROP_BOOL("acpi-pci-hotplug-with-bridge-support",
> PIIX4PMState,
> >                       use_acpi_hotplug_bridge, true),
> > +    DEFINE_PROP_BOOL("acpi-pci-hotplug", PIIX4PMState,
> > +                     use_acpi_pci_hotplug, true),
> >      DEFINE_PROP_BOOL("memory-hotplug-support", PIIX4PMState,
> >                       acpi_memory_hotplug.is_enabled, true),
> >      DEFINE_PROP_END_OF_LIST(),
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index b7bcbbb..343b9b6 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -95,6 +95,7 @@ typedef struct AcpiPmInfo {
> >      bool s3_disabled;
> >      bool s4_disabled;
> >      bool pcihp_bridge_en;
> > +    bool pcihp_en;
> >      uint8_t s4_val;
> >      AcpiFadtData fadt;
> >      uint16_t cpu_hp_io_base;
> > @@ -245,6 +246,9 @@ static void acpi_get_pm_info(MachineState *machine,
> AcpiPmInfo *pm)
> >      pm->pcihp_bridge_en =
> >          object_property_get_bool(obj,
> "acpi-pci-hotplug-with-bridge-support",
> >                                   NULL);
> > +    pm->pcihp_en =
> > +        object_property_get_bool(obj, "acpi-pci-hotplug", NULL);
> > +
> >  }
> >
> >  static void acpi_get_misc_info(AcpiMiscInfo *info)
> > @@ -337,14 +341,16 @@ static void build_append_pcihp_notify_entry(Aml
> *method, int slot)
> >  }
> >
> >  static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
> > -                                         bool pcihp_bridge_en)
> > +                                         bool pcihp_bridge_en, bool
> pcihp_en)
> >  {
> >      Aml *dev, *notify_method = NULL, *method;
> > -    QObject *bsel;
> > +    QObject *bsel = NULL;
> >      PCIBus *sec;
> >      int i;
> >
> > -    bsel = object_property_get_qobject(OBJECT(bus),
> ACPI_PCIHP_PROP_BSEL, NULL);
> > +    if (pcihp_en)
> > +        bsel = object_property_get_qobject(OBJECT(bus),
> > +                                           ACPI_PCIHP_PROP_BSEL, NULL);
> >      if (bsel) {
> >          uint64_t bsel_val = qnum_get_uint(qobject_to(QNum, bsel));
> >
> > @@ -439,7 +445,8 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
> >               */
> >              PCIBus *sec_bus = pci_bridge_get_sec_bus(PCI_BRIDGE(pdev));
> >
> > -            build_append_pci_bus_devices(dev, sec_bus, pcihp_bridge_en);
> > +            build_append_pci_bus_devices(dev, sec_bus, pcihp_bridge_en,
> > +                                         pcihp_en);
> >          }
> >          /* slot descriptor has been composed, add it into parent
> context */
> >          aml_append(parent_scope, dev);
> > @@ -468,7 +475,7 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
> >      }
> >
> >      /* Notify about child bus events in any case */
> > -    if (pcihp_bridge_en) {
> > +    if (pcihp_bridge_en && pcihp_en) {
> >          QLIST_FOREACH(sec, &bus->child, sibling) {
> >              int32_t devfn = sec->parent_dev->devfn;
> >
> > @@ -1818,7 +1825,8 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> >          if (bus) {
> >              Aml *scope = aml_scope("PCI0");
> >              /* Scan all PCI buses. Generate tables to support hotplug.
> */
> > -            build_append_pci_bus_devices(scope, bus,
> pm->pcihp_bridge_en);
> > +            build_append_pci_bus_devices(scope, bus,
> pm->pcihp_bridge_en,
> > +                                         pm->pcihp_en);
> >
> >              if (TPM_IS_TIS_ISA(tpm)) {
> >                  if (misc->tpm_version == TPM_VERSION_2_0) {
> > --
> > 2.7.4
>
>

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