On Fri, 21 Aug 2020 11:16:12 +0200 Igor Mammedov <imamm...@redhat.com> wrote:
> On Thu, 20 Aug 2020 22:11:41 +0530 > Ani Sinha <a...@anisinha.ca> wrote: > > > > On Aug 20, 2020, at 9:11 PM, Ani Sinha <a...@anisinha.ca> wrote: > > > > > > On Thu, Aug 20, 2020 at 7:37 PM Igor Mammedov <imamm...@redhat.com> > > > wrote: > > >> > > >>> On Thu, 20 Aug 2020 14:51:56 +0530 > > >>> Ani Sinha <a...@anisinha.ca> wrote: > > >>> > > >>> We introduce a new global flag 'acpi-root-pci-hotplug' for i440fx with > > >>> which > > >>> we can turn on or off PCI device hotplug on the root bus. This flag can > > >>> 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 that > > >>> 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 > > >>> detail: > > >>> https://www.redhat.com/archives/libvir-list/2020-February/msg00110.html > > >>> > > >>> Julia has resolved this issue for PCIE buses with the following commit: > > >>> 530a0963184e57e71a5b538 ("pcie_root_port: Add hotplug disabling option") > > >>> > > >>> 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-slot > > >>> capability to turn hotplug on or off). > > >>> > > >>> Usage: > > >>> -global PIIX4_PM.acpi-root-pci-hotplug=off > > >>> > > >>> By default, this option is enabled which means that hotplug is turned > > >>> on for > > >>> the PCI root bus. > > >>> > > >>> The previously existing flag 'acpi-pci-hotplug-with-bridge-support' for > > >>> PCI-PCI > > >>> bridges remain as is and can be used along with this new flag to > > >>> control PCI > > >>> hotplug on PCI bridges. > > >>> > > >>> 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 the > > >>> latest > > >>> master qemu from upstream (v5.1.0 tag). > > >>> > > >>> Signed-off-by: Ani Sinha <a...@anisinha.ca> > > >>> --- > > >>> hw/acpi/piix4.c | 8 ++++++-- > > >>> hw/i386/acpi-build.c | 26 +++++++++++++++++++------- > > >>> 2 files changed, 25 insertions(+), 9 deletions(-) > > >>> > > >>> Change Log: > > >>> V5..V6: specified upstream master tag information off which this patch > > >>> is > > >>> based off of. > > >>> > > >>> 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 { > > >>> > > >>> AcpiPciHpState acpi_pci_hotplug; > > >>> bool use_acpi_hotplug_bridge; > > >>> + bool use_acpi_root_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_hotplug_bridge || s->use_acpi_root_pci_hotplug) > > >>> + acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent, > > >>> + s->use_acpi_hotplug_bridge); > > >> 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. > > >> > > >> Without this hunk patch is fine, as a means to hide hotplug from Windows. > > >> > > >> 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. > > > > > > Ok maybe I will just remove it. That's what I'd do, so that mostly AML part will be merged first and then work on properly disabling hw parts as a separate patch. Also Julia might borrow "acpi-root-pci-hotplug" for here q35 work. > > > > > >> > > >> > > >>> 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-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 *machine, > > >>> AcpiPmInfo *pm) > > >>> pm->pcihp_bridge_en = > > >>> object_property_get_bool(obj, > > >>> "acpi-pci-hotplug-with-bridge-support", > > >>> NULL); > > >>> + pm->pcihp_root_en = > > >>> + object_property_get_bool(obj, "acpi-root-pci-hotplug", NULL); > > >>> + > > >>> } > > >>> [...]
