Re: [PATCH 5/9] i440fx/acpi: do not add hotplug related amls for cold plugged bridges

[Ani Sinha]

On Mon, Sep 14, 2020 at 6:07 PM Igor Mammedov <imammedo@redhat.com> wrote:
>
> On Fri, 11 Sep 2020 23:37:51 +0530
> Ani Sinha <ani@anisinha.ca> 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
> >
> > As a result of the patch, the following are the changes to the DSDT ACPI 
> > table:
> >
> > @@ -858,38 +858,33 @@
> >                      Return (Zero)
> >                  }
> >
> >                  Method (_S2D, 0, NotSerialized)  // _S2D: S2 Device State
> >                  {
> >                      Return (Zero)
> >                  }
> >
> >                  Method (_S3D, 0, NotSerialized)  // _S3D: S3 Device State
> >                  {
> >                      Return (Zero)
> >                  }
> >              }
> >
> >              Device (S18)
> >              {
> > -                Name (_SUN, 0x03)  // _SUN: Slot User Number
> >                  Name (_ADR, 0x00030000)  // _ADR: Address
> > -                Method (_EJ0, 1, NotSerialized)  // _EJx: Eject Device
> > -                {
> > -                    PCEJ (BSEL, _SUN)
> > -                }
> >              }
> >
> >              Device (S20)
> >              {
> >                  Name (_SUN, 0x04)  // _SUN: Slot User Number
> >                  Name (_ADR, 0x00040000)  // _ADR: Address
> >                  Method (_EJ0, 1, NotSerialized)  // _EJx: Eject Device
> >                  {
> >                      PCEJ (BSEL, _SUN)
> >                  }
> >              }
> >
> >              Device (S28)
> >              {
> >                  Name (_SUN, 0x05)  // _SUN: Slot User Number
> >                  Name (_ADR, 0x00050000)  // _ADR: Address
> > @@ -1148,37 +1143,32 @@
> >                      PCEJ (BSEL, _SUN)
> >                  }
> >              }
> >
> >              Device (SF8)
> >              {
> >                  Name (_SUN, 0x1F)  // _SUN: Slot User Number
> >                  Name (_ADR, 0x001F0000)  // _ADR: Address
> >                  Method (_EJ0, 1, NotSerialized)  // _EJx: Eject Device
> >                  {
> >                      PCEJ (BSEL, _SUN)
> >                  }
> >              }
> >
> >              Method (DVNT, 2, NotSerialized)
> >              {
> > -                If ((Arg0 & 0x08))
> > -                {
> > -                    Notify (S18, Arg1)
> > -                }
> > -
> >                  If ((Arg0 & 0x10))
> >                  {
> >                      Notify (S20, Arg1)
> >                  }
> >
> >                  If ((Arg0 & 0x20))
> >                  {
> >                      Notify (S28, Arg1)
> >                  }
> >
> >                  If ((Arg0 & 0x40))
> >                  {
> >                      Notify (S30, Arg1)
> >                  }
> >
> >                  If ((Arg0 & 0x80))
> >
> > 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 <ani@anisinha.ca>
>
> Reviewed-by: Igor Mammedov <imammedo@redhat.com>

Reviewed-by: Julia Suvorova <jusual@redhat.com>

>From the previous thread.

>
> > ---
> >  hw/i386/acpi-build.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index 7a5a8b3521..e079b686f5 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;
>