From 64a55106e4b9f5248f096bf158a9242c2b5cc8b9 Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Thu, 12 Jan 2023 15:03:08 +0100 Subject: [PATCH] pcihp: acpi: ignore coldplugged bridges when composing hotpluggable slots coldplugged bridges are not unpluggable, so there is no need to describe slots where they are plugged as hotpluggable. To that effect we have a condition that marks slot as non-hotpluggable if it's populated by coldplugged bridge and prevents generation _SUN/_EJ0 objects for it. That leaves dynamic _DSM method on such slot (which also depends on BSEL and pcihp hardware). This _DSM method provides only dynamic acpi-index support so far, which is not actually used/supported by linux kernel for bridges and it's doubtful there will be need for it at all. So it's rather pointless to generate acpi-index related AML for bridges and we can simplify hotplug slots generator a bit more by completely ignoring coldplugged bridges on hotplug path. Another point in favor of dropping dynamic _DSM support, is that we can replace it with static _DSM if necessary since a slot with bridge can't change during VM runtime and without any dependency on ACPI PCI hotplug at that. Later I plan to implement bridge specific static _DSM PCI Firmware Specification 3.2 4.6.5. _DSM for Ignoring PCI Boot Configurations part of spec, to fix longstanding issue with fixed IO/MEM resource assignment that often leads to hotplugged device being in-operational within the guest due limited IO/MEM windows programmed on bridge at boot time. Expected change when coldplugged bridge is ignored by hotplug code, should look like: - Scope (S18) - { - Name (ASUN, 0x03) - Method (_DSM, 4, Serialized) // _DSM: Device-Specific Method - { - Local0 = Package (0x02) - { - BSEL, - ASUN - } - Return (PDSM (Arg0, Arg1, Arg2, Arg3, Local0)) - } - } Signed-off-by: Igor Mammedov Message-Id: <20230112140312.3096331-37-imammedo@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/i386/acpi-build.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c index 2077efbee4..a02608c215 100644 --- a/hw/i386/acpi-build.c +++ b/hw/i386/acpi-build.c @@ -409,8 +409,11 @@ static bool is_devfn_ignored_generic(const int devfn, const PCIBus *bus) static bool is_devfn_ignored_hotplug(const int devfn, const PCIBus *bus) { - if (bus->devices[devfn]) { - return is_devfn_ignored_generic(devfn, bus); + PCIDevice *pdev = bus->devices[devfn]; + if (pdev) { + return is_devfn_ignored_generic(devfn, bus) || + /* Cold plugged bridges aren't themselves hot-pluggable */ + (IS_PCI_BRIDGE(pdev) && !DEVICE(pdev)->hotplugged); } else { /* non populated slots */ /* * hotplug is supported only for non-multifunction device @@ -445,14 +448,7 @@ static void build_append_pcihp_slots(Aml *parent_scope, PCIBus *bus, } if (pdev) { - /* - * Cold plugged bridges aren't themselves hot-pluggable. - * Hotplugged bridges *are* hot-pluggable. - */ - bool cold_plugged_bridge = IS_PCI_BRIDGE(pdev) && - !DEVICE(pdev)->hotplugged; - hotpluggbale_slot = DEVICE_GET_CLASS(pdev)->hotpluggable && - !cold_plugged_bridge; + hotpluggbale_slot = DEVICE_GET_CLASS(pdev)->hotpluggable; dev = aml_scope("S%.02X", devfn); } else { dev = aml_device("S%.02X", devfn); -- 2.11.4.GIT