On Sep 10, 2020, 00:00 +0530, Ani Sinha , wrote: > On Sep 9, 2020, 23:20 +0530, Julia Suvorova , wrote: > > On Fri, Sep 4, 2020 at 6:10 PM Ani Sinha wrote: > > > > > > Cold plugged bridges are not hot unpluggable, even when their hotplug > > > property (acpi-pci-hotplug-with-bridge-support) is turned off. Please see > > > the function acpi_pcihp_pc_no_hotplug() (thanks Julia). However, with > > > the current implementaton, windows would try to hot-unplug a pci bridge when > > > it's hotplug switch is off. This is regardless of whether there are devices > > > attached to the bridge. This is because we add amls like _EJ0 etc for the > > > pci slot where the bridge is cold plugged. We have a demo video here: > > > https://youtu.be/pME2sjyQweo > > > > > > In this fix, we identify a cold plugged bridge and for cold plugged bridges, > > > we do not add the appropriate amls and acpi methods that are used by the OS > > > to identify a hot-pluggable/unpluggable pci device. After this change, Windows > > > does not show an option to eject the PCI bridge. A demo video is here: > > > https://youtu.be/kbgej5B9Hgs > > > > > > While at it, I have also updated a stale comment. > > > > > > This change is tested with a Windows 2012R2 guest image and Windows 2019 server > > > guest image running on Ubuntu 18.04 host. This change is based off of upstream > > > qemu master branch tag v5.1.0. > > > > > > Signed-off-by: Ani Sinha > > > > Reviewed-by: Julia Suvorova > > > > BTW, aren't all bridges handled in build_append_pci_bus_devices() cold-plugged? > > Yes they are. Maybe as an improvement we can simply identify a bridge instead of a cold plugged bridge. However let’s have that improvement as a separate patch on top of this. Also let’s see what Igor thinks. > > > > > --- > > > hw/i386/acpi-build.c | 12 ++++++------ > > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > > > changelog: > > > v3: commit log updates providing more accurate information as received from Julia. > > > v2: cosmetic commit log updates with patch testing information. > > > v1: initial patch. > > > > > > > > > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c > > > index b7bcbbbb2a..90b863f4ec 100644 > > > --- a/hw/i386/acpi-build.c > > > +++ b/hw/i386/acpi-build.c > > > @@ -359,6 +359,7 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus, > > > int slot = PCI_SLOT(i); > > > bool hotplug_enabled_dev; > > > bool bridge_in_acpi; > > > + bool cold_plugged_bridge; > > > > > > if (!pdev) { > > > if (bsel) { /* add hotplug slots for non present devices */ > > > @@ -380,15 +381,14 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus, > > > pc = PCI_DEVICE_GET_CLASS(pdev); > > > dc = DEVICE_GET_CLASS(pdev); > > > > > > - /* When hotplug for bridges is enabled, bridges are > > > - * described in ACPI separately (see build_pci_bus_end). > > > - * In this case they aren't themselves hot-pluggable. > > > + /* > > > + * Cold plugged bridges aren't themselves hot-pluggable. > > > * Hotplugged bridges *are* hot-pluggable. > > > */ > > > - bridge_in_acpi = pc->is_bridge && pcihp_bridge_en && > > > - !DEVICE(pdev)->hotplugged; > > > + cold_plugged_bridge = pc->is_bridge && !DEVICE(pdev)->hotplugged; > > > + bridge_in_acpi = cold_plugged_bridge && pcihp_bridge_en; > > > > > > - hotplug_enabled_dev = bsel && dc->hotpluggable && !bridge_in_acpi; > > > + hotplug_enabled_dev = bsel && dc->hotpluggable && !cold_plugged_bridge; > > > > > > if (pc->class_id == PCI_CLASS_BRIDGE_ISA) { > > > continue; > > > -- > > > 2.17.1 > > > > >