From 3d7e78aa7777f052d72ec6070e611767f0db35ce Mon Sep 17 00:00:00 2001 From: Ani Sinha Date: Fri, 21 Aug 2020 22:24:03 +0530 Subject: Introduce a new flag for i440fx to disable PCI hotplug on the root bus 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. Signed-off-by: Ani Sinha Message-Id: <20200821165403.26589-1-ani@anisinha.ca> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Tested-by: Igor Mammedov Reviewed-by: Igor Mammedov --- hw/acpi/pcihp.c | 23 ++++++++++++++++++++++- hw/acpi/piix4.c | 5 ++++- 2 files changed, 26 insertions(+), 2 deletions(-) (limited to 'hw/acpi') diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c index 9e31ab2da4..39b1f74442 100644 --- a/hw/acpi/pcihp.c +++ b/hw/acpi/pcihp.c @@ -104,6 +104,24 @@ static void acpi_set_pci_info(void) } } +static void acpi_pcihp_disable_root_bus(void) +{ + static bool root_hp_disabled; + PCIBus *bus; + + if (root_hp_disabled) { + return; + } + + bus = find_i440fx(); + if (bus) { + /* setting the hotplug handler to NULL makes the bus non-hotpluggable */ + qbus_set_hotplug_handler(BUS(bus), NULL); + } + root_hp_disabled = true; + return; +} + static void acpi_pcihp_test_hotplug_bus(PCIBus *bus, void *opaque) { AcpiPciHpFind *find = opaque; @@ -209,8 +227,11 @@ static void acpi_pcihp_update(AcpiPciHpState *s) } } -void acpi_pcihp_reset(AcpiPciHpState *s) +void acpi_pcihp_reset(AcpiPciHpState *s, bool acpihp_root_off) { + if (acpihp_root_off) { + acpi_pcihp_disable_root_bus(); + } acpi_set_pci_info(); acpi_pcihp_update(s); } diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c index 26bac4f16c..e6163bb6ce 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; @@ -324,7 +325,7 @@ static void piix4_pm_reset(DeviceState *dev) pci_conf[0x5B] = 0x02; } pm_io_space_update(s); - acpi_pcihp_reset(&s->acpi_pci_hotplug); + acpi_pcihp_reset(&s->acpi_pci_hotplug, !s->use_acpi_root_pci_hotplug); } static void piix4_pm_powerdown_req(Notifier *n, void *opaque) @@ -635,6 +636,8 @@ 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(), -- cgit v1.2.3-55-g7522