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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 11:19:45 -0400 |
On Mon, Aug 10, 2020 at 08:35:56PM +0530, Ani Sinha wrote:
>
> Ani
> On Aug 10, 2020, 20:30 +0530, Michael S. Tsirkin <mst@redhat.com>, wrote:
>
> 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.
>
>
> I think the global option should override the bridge option. So if the global
> option disables hotplug, the bridge option should be a noop.
>
Well just ignoring inconsistent user input does not sound great.
Tends to create support problems.
>
>
>
>
>
>
>
>
>
>
>
> ---
>
> 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
>
>
>
>
>
>
>