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Re: [PATCH] Introduce global piix flag to disable PCI hotplug
From: |
Michael S. Tsirkin |
Subject: |
Re: [PATCH] Introduce global piix flag to disable PCI hotplug |
Date: |
Mon, 10 Aug 2020 11:00:01 -0400 |
On Mon, Aug 10, 2020 at 08:24:53PM +0530, Ani Sinha wrote:
>
>
> 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.
>
I can certainly see the attraction of a global flag.
However, with the interface we have for bridges right now, how are we
going to resolve the conflict if hotplug is disabled globally but
enabled for a given bridge?
A reasonable way would be to change the default value for bridges,
have a user-specified value override it.
This patch doesn't do it, though.
>
>
> > ---
> > hw/acpi/piix4.c   | 8 ++++++--
> >Â hw/i386/acpi-build.c | 20 ++++++++++++++------
> >Â 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 {
> >Â
> >Â Â Â AcpiPciHpState acpi_pci_hotplug;
> >Â Â Â bool use_acpi_hotplug_bridge;
> > +Â Â bool use_acpi_pci_hotplug;
> >Â
> >Â Â Â uint8_t disable_s3;
> >Â Â Â uint8_t disable_s4;
> > @@ -595,8 +596,9 @@ static void piix4_acpi_system_hot_add_init
> (MemoryRegion *parent,
> >Â Â Â Â Â Â Â Â Â Â Â Â Â Â "acpi-gpe0", GPE_LEN);
> >Â Â Â memory_region_add_subregion(parent, GPE_BASE, &s->io_gpe);
> >Â
> > -Â Â acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent,
> > -Â Â Â Â Â Â Â Â Â Â s->use_acpi_hotplug_bridge);
> > +Â Â if (s->use_acpi_pci_hotplug)
> > +Â Â Â Â acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus,
> parent,
> > +Â Â Â Â Â Â Â Â Â Â Â Â s->use_acpi_hotplug_bridge);
> >Â
> >Â Â Â s->cpu_hotplug_legacy = true;
> >Â Â Â object_property_add_bool(OBJECT(s), "cpu-hotplug-legacy",
> > @@ -635,6 +637,8 @@ static Property piix4_pm_properties[] = {
> >Â Â Â DEFINE_PROP_UINT8(ACPI_PM_PROP_S4_VAL, PIIX4PMState, s4_val, 2),
> >Â Â Â DEFINE_PROP_BOOL("acpi-pci-hotplug-with-bridge-support",
> PIIX4PMState,
> >Â Â Â Â Â Â Â Â Â Â Â Â use_acpi_hotplug_bridge, true),
> > +Â Â DEFINE_PROP_BOOL("acpi-pci-hotplug", PIIX4PMState,
> > +Â Â Â Â Â Â Â Â Â Â Â use_acpi_pci_hotplug, true),
> >Â Â Â DEFINE_PROP_BOOL("memory-hotplug-support", PIIX4PMState,
> >Â Â Â Â Â Â Â Â Â Â Â Â acpi_memory_hotplug.is_enabled, true),
> >Â Â Â 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 {
> >Â Â Â bool s3_disabled;
> >Â Â Â bool s4_disabled;
> >Â Â Â bool pcihp_bridge_en;
> > +Â Â bool pcihp_en;
> >Â Â Â uint8_t s4_val;
> >Â Â Â AcpiFadtData fadt;
> >Â Â Â uint16_t cpu_hp_io_base;
> > @@ -245,6 +246,9 @@ static void acpi_get_pm_info(MachineState *machine,
> AcpiPmInfo *pm)
> >Â Â Â pm->pcihp_bridge_en =
> >Â Â Â Â Â object_property_get_bool(obj,
> "acpi-pci-hotplug-with-bridge-support",
> >Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â NULL);
> > +Â Â pm->pcihp_en =
> > +Â Â Â Â object_property_get_bool(obj, "acpi-pci-hotplug", NULL);
> > +
> >Â }
> >Â
> >Â static void acpi_get_misc_info(AcpiMiscInfo *info)
> > @@ -337,14 +341,16 @@ static void build_append_pcihp_notify_entry(Aml
> *method, int slot)
> >Â }
> >Â
> >Â static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus
> *bus,
> > -Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â bool
> pcihp_bridge_en)
> > +Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â bool
> pcihp_bridge_en, bool
> pcihp_en)
> >Â {
> >Â Â Â Aml *dev, *notify_method = NULL, *method;
> > -Â Â QObject *bsel;
> > +Â Â QObject *bsel = NULL;
> >Â Â Â PCIBus *sec;
> >Â Â Â int i;
> >Â
> > -Â Â bsel = object_property_get_qobject(OBJECT(bus),
> ACPI_PCIHP_PROP_BSEL, NULL);
> > +Â Â if (pcihp_en)
> > +Â Â Â Â bsel = object_property_get_qobject(OBJECT(bus),
> > +Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
> ACPI_PCIHP_PROP_BSEL, NULL);
> >Â Â Â if (bsel) {
> >Â Â Â Â Â uint64_t bsel_val = qnum_get_uint(qobject_to(QNum, bsel));
> >Â
> > @@ -439,7 +445,8 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
> >Â Â Â Â Â Â Â Â */
> >Â Â Â Â Â Â Â PCIBus *sec_bus =
> pci_bridge_get_sec_bus(PCI_BRIDGE(pdev));
> >Â
> > -Â Â Â Â Â Â build_append_pci_bus_devices(dev, sec_bus,
> pcihp_bridge_en);
> > +Â Â Â Â Â Â build_append_pci_bus_devices(dev, sec_bus,
> pcihp_bridge_en,
> > +Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
> pcihp_en);
> >Â Â Â Â Â }
> >Â Â Â Â Â /* slot descriptor has been composed, add it into parent
> context
> */
> >Â Â Â Â Â aml_append(parent_scope, dev);
> > @@ -468,7 +475,7 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
> >Â Â Â }
> >Â
> >Â Â Â /* Notify about child bus events in any case */
> > -Â Â if (pcihp_bridge_en) {
> > +Â Â if (pcihp_bridge_en && pcihp_en) {
> >Â Â Â Â Â QLIST_FOREACH(sec, &bus->child, sibling) {
> >Â Â Â Â Â Â Â int32_t devfn = sec->parent_dev->devfn;
> >Â
> > @@ -1818,7 +1825,8 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> >Â Â Â Â Â if (bus) {
> >Â Â Â Â Â Â Â Aml *scope = aml_scope("PCI0");
> >Â Â Â Â Â Â Â /* Scan all PCI buses. Generate tables to support
> hotplug. *
> /
> > -Â Â Â Â Â Â build_append_pci_bus_devices(scope, bus, pm->
> pcihp_bridge_en);
> > +Â Â Â Â Â Â build_append_pci_bus_devices(scope, bus, pm->
> pcihp_bridge_en,
> > +Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
> pm->pcihp_en);
> >Â
> >Â Â Â Â Â Â Â if (TPM_IS_TIS_ISA(tpm)) {
> >Â Â Â Â Â Â Â Â Â if (misc->tpm_version == TPM_VERSION_2_0) {
> > --
> > 2.7.4
>
>