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Tsirkin" , qemu-devel@nongnu.org, Aleksandar Markovic , Paolo Bonzini , Philippe =?UTF-8?B?TWF0aGlldS1EYXVkw6k=?= , Aurelien Jarno , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 20 Aug 2020 22:11:41 +0530 Ani Sinha wrote: > > On Aug 20, 2020, at 9:11 PM, Ani Sinha wrote: > >=20 > > =EF=BB=BFOn Thu, Aug 20, 2020 at 7:37 PM Igor Mammedov wrote: =20 > >> =20 > >>> On Thu, 20 Aug 2020 14:51:56 +0530 > >>> Ani Sinha wrote: > >>>=20 > >>> We introduce a new global flag 'acpi-root-pci-hotplug' for i440fx wit= h which > >>> we can turn on or off PCI device hotplug on the root bus. This flag c= an be > >>> used to prevent all PCI devices from getting hotplugged or unplugged = from the > >>> root PCI bus. > >>> This feature is targetted mostly towards Windows VMs. It is useful in= cases > >>> where some hypervisor admins want to deploy guest VMs in a way so tha= t the > >>> users of the guest OSes are not able to hot-eject certain PCI devices= from > >>> the Windows system tray. Laine has explained the use case here in det= ail: > >>> https://www.redhat.com/archives/libvir-list/2020-February/msg00110.ht= ml > >>>=20 > >>> Julia has resolved this issue for PCIE buses with the following commi= t: > >>> 530a0963184e57e71a5b538 ("pcie_root_port: Add hotplug disabling optio= n") > >>>=20 > >>> This commit attempts to introduce similar behavior for PCI root buses= used in > >>> i440fx machine types (although in this case, we do not have a per-slo= t > >>> capability to turn hotplug on or off). > >>>=20 > >>> Usage: > >>> -global PIIX4_PM.acpi-root-pci-hotplug=3Doff > >>>=20 > >>> By default, this option is enabled which means that hotplug is turned= on for > >>> the PCI root bus. > >>>=20 > >>> The previously existing flag 'acpi-pci-hotplug-with-bridge-support' f= or PCI-PCI > >>> bridges remain as is and can be used along with this new flag to cont= rol PCI > >>> hotplug on PCI bridges. > >>>=20 > >>> This change has been tested using a Windows 2012R2 server guest image= and also > >>> with a Windows 2019 server guest image on a Ubuntu 18.04 host using t= he latest > >>> master qemu from upstream (v5.1.0 tag). > >>>=20 > >>> Signed-off-by: Ani Sinha > >>> --- > >>> hw/acpi/piix4.c | 8 ++++++-- > >>> hw/i386/acpi-build.c | 26 +++++++++++++++++++------- > >>> 2 files changed, 25 insertions(+), 9 deletions(-) > >>>=20 > >>> Change Log: > >>> V5..V6: specified upstream master tag information off which this patc= h is > >>> based off of. > >>>=20 > >>> diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c > >>> index 26bac4f16c..4f436e5bf3 100644 > >>> --- a/hw/acpi/piix4.c > >>> +++ b/hw/acpi/piix4.c > >>> @@ -78,6 +78,7 @@ typedef struct PIIX4PMState { > >>>=20 > >>> AcpiPciHpState acpi_pci_hotplug; > >>> bool use_acpi_hotplug_bridge; > >>> + bool use_acpi_root_pci_hotplug; > >>>=20 > >>> uint8_t disable_s3; > >>> uint8_t disable_s4; =20 > >> =20 > >>> @@ -595,8 +596,9 @@ static void piix4_acpi_system_hot_add_init(Memory= Region *parent, > >>> "acpi-gpe0", GPE_LEN); > >>> memory_region_add_subregion(parent, GPE_BASE, &s->io_gpe); > >>>=20 > >>> - acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent, > >>> - s->use_acpi_hotplug_bridge); > >>> + if (s->use_acpi_hotplug_bridge || s->use_acpi_root_pci_hotplug) > >>> + acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent= , > >>> + s->use_acpi_hotplug_bridge); =20 > >> If intent was to disable hardware part of ACPI hotplug, > >> then this hunk is not enough. I'd say it introduces bug since you are = leaving > >> device_add/del route open and "_E01" AML code around trying to access = no longer > >> described/present io ports. > >>=20 > >> Without this hunk patch is fine, as a means to hide hotplug from Windo= ws. > >>=20 > >> If you'd like to disable hw part, you will need to consider case where= hotplug is > >> disabled completly and block all related AML and block device_add|del. > >> So it would be a bit more than above hunk. =20 > >=20 > > Ok maybe I will just remove it. > > =20 > >>=20 > >> =20 > >>> s->cpu_hotplug_legacy =3D true; > >>> object_property_add_bool(OBJECT(s), "cpu-hotplug-legacy", > >>> @@ -635,6 +637,8 @@ static Property piix4_pm_properties[] =3D { > >>> DEFINE_PROP_UINT8(ACPI_PM_PROP_S4_VAL, PIIX4PMState, s4_val, 2), > >>> DEFINE_PROP_BOOL("acpi-pci-hotplug-with-bridge-support", PIIX4PMS= tate, > >>> use_acpi_hotplug_bridge, true), > >>> + DEFINE_PROP_BOOL("acpi-root-pci-hotplug", PIIX4PMState, > >>> + use_acpi_root_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 b7bcbbbb2a..19a1702ad1 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_root_en; > >>> uint8_t s4_val; > >>> AcpiFadtData fadt; > >>> uint16_t cpu_hp_io_base; > >>> @@ -245,6 +246,9 @@ static void acpi_get_pm_info(MachineState *machin= e, AcpiPmInfo *pm) > >>> pm->pcihp_bridge_en =3D > >>> object_property_get_bool(obj, "acpi-pci-hotplug-with-bridge-s= upport", > >>> NULL); > >>> + pm->pcihp_root_en =3D > >>> + object_property_get_bool(obj, "acpi-root-pci-hotplug", NULL)= ; > >>> + > >>> } > >>>=20 > >>> static void acpi_get_misc_info(AcpiMiscInfo *info) > >>> @@ -337,15 +341,18 @@ static void build_append_pcihp_notify_entry(Aml= *method, int slot) > >>> } > >>>=20 > >>> static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *b= us, > >>> - bool pcihp_bridge_en) > >>> + bool pcihp_bridge_en, > >>> + bool pcihp_root_en) > >>> { > >>> Aml *dev, *notify_method =3D NULL, *method; > >>> QObject *bsel; > >>> PCIBus *sec; > >>> int i; > >>> + bool root_bus =3D pci_bus_is_root(bus); > >>> + bool root_pcihp_disabled =3D (root_bus && !pcihp_root_en); > >>>=20 > >>> bsel =3D object_property_get_qobject(OBJECT(bus), ACPI_PCIHP_PROP= _BSEL, NULL); > >>> - if (bsel) { > >>> + if (bsel && !root_pcihp_disabled) { =20 > >>=20 > >> have you considered to make bus not hotpluggable, > >> which should make it not to have bsel, and hence skip this branch with= out > >> root_pcihp_disabled? > >>=20 > >> see: acpi_set_bsel() > >>=20 > >>=20 > >> maybe you can drop pcihp_root_en and use bsel instead of it then. > >>=20 > >> it also should block device_add/del route. =20 > >=20 > > This is a good idea. Therefore, I tried this: > >=20 > > --- a/hw/acpi/piix4.c > > +++ b/hw/acpi/piix4.c > > @@ -28,6 +28,7 @@ > > #include "hw/pci/pci.h" > > #include "hw/qdev-properties.h" > > #include "hw/acpi/acpi.h" > > +#include "hw/pci/pci_bus.h" > > #include "sysemu/runstate.h" > > #include "sysemu/sysemu.h" > > #include "sysemu/xen.h" > > @@ -507,7 +508,9 @@ static void piix4_pm_realize(PCIDevice *dev, Error = **errp) > >=20 > > piix4_acpi_system_hot_add_init(pci_address_space_io(dev), > > pci_get_bus(dev), s); > > - qbus_set_hotplug_handler(BUS(pci_get_bus(dev)), OBJECT(s)); > > + if (s->use_acpi_root_pci_hotplug || > > + !pci_bus_is_root(pci_get_bus(dev))) > > + qbus_set_hotplug_handler(BUS(pci_get_bus(dev)), OBJECT(s)); > >=20 > > piix4_pm_add_propeties(s); > > } > >=20 > >=20 > > but this does not seem to be working. I am out of ideas as to why it > > wouldn't work :( =20 >=20 > By that I mean the devices attached to bridges also seems to be disabled = from hotplug from within Windows. I do not understand why that would be the= case when the pci_bus_is_root() should be false for the secondary buses. >=20 > Any ideas? Looking at acpi_set_pci_info() and debugging it might help. >=20 > > =20 > >>=20 > >> =20 > >>> uint64_t bsel_val =3D qnum_get_uint(qobject_to(QNum, bsel)); > >>>=20 > >>> aml_append(parent_scope, aml_name_decl("BSEL", aml_int(bsel_v= al))); > >>> @@ -361,6 +368,9 @@ static void build_append_pci_bus_devices(Aml *par= ent_scope, PCIBus *bus, > >>> bool bridge_in_acpi; > >>>=20 > >>> if (!pdev) { > >>> + /* skip if pci hotplug for the root bus is disabled */ > >>> + if (root_pcihp_disabled) > >>> + continue; > >>> if (bsel) { /* add hotplug slots for non present devices = */ > >>> dev =3D aml_device("S%.02X", PCI_DEVFN(slot, 0)); > >>> aml_append(dev, aml_name_decl("_SUN", aml_int(slot)))= ; > >>> @@ -419,7 +429,7 @@ static void build_append_pci_bus_devices(Aml *par= ent_scope, PCIBus *bus, > >>> method =3D aml_method("_S3D", 0, AML_NOTSERIALIZED); > >>> aml_append(method, aml_return(aml_int(s3d))); > >>> aml_append(dev, method); > >>> - } else if (hotplug_enabled_dev) { > >>> + } else if (hotplug_enabled_dev && !root_pcihp_disabled) { > >>> /* add _SUN/_EJ0 to make slot hotpluggable */ > >>> aml_append(dev, aml_name_decl("_SUN", aml_int(slot))); > >>>=20 > >>> @@ -439,13 +449,14 @@ static void build_append_pci_bus_devices(Aml *p= arent_scope, PCIBus *bus, > >>> */ > >>> PCIBus *sec_bus =3D pci_bridge_get_sec_bus(PCI_BRIDGE(pde= v)); > >>>=20 > >>> - build_append_pci_bus_devices(dev, sec_bus, pcihp_bridge_= en); > >>> + build_append_pci_bus_devices(dev, sec_bus, pcihp_bridge_= en, > >>> + pcihp_root_en); > >>> } > >>> /* slot descriptor has been composed, add it into parent cont= ext */ > >>> aml_append(parent_scope, dev); > >>> } > >>>=20 > >>> - if (bsel) { > >>> + if (bsel && !root_pcihp_disabled) { > >>> aml_append(parent_scope, notify_method); > >>> } > >>>=20 > >>> @@ -455,7 +466,7 @@ static void build_append_pci_bus_devices(Aml *par= ent_scope, PCIBus *bus, > >>> method =3D aml_method("PCNT", 0, AML_NOTSERIALIZED); > >>>=20 > >>> /* If bus supports hotplug select it and notify about local event= s */ > >>> - if (bsel) { > >>> + if (bsel && !root_pcihp_disabled) { > >>> uint64_t bsel_val =3D qnum_get_uint(qobject_to(QNum, bsel)); > >>>=20 > >>> aml_append(method, aml_store(aml_int(bsel_val), aml_name("BNU= M"))); > >>> @@ -1818,7 +1829,8 @@ build_dsdt(GArray *table_data, BIOSLinker *link= er, > >>> if (bus) { > >>> Aml *scope =3D aml_scope("PCI0"); > >>> /* Scan all PCI buses. Generate tables to support hotplug= . */ > >>> - build_append_pci_bus_devices(scope, bus, pm->pcihp_bridg= e_en); > >>> + build_append_pci_bus_devices(scope, bus, pm->pcihp_bridg= e_en, > >>> + pm->pcihp_root_en); > >>>=20 > >>> if (TPM_IS_TIS_ISA(tpm)) { > >>> if (misc->tpm_version =3D=3D TPM_VERSION_2_0) { =20 > >> =20 >=20