Re: [PATCH v4 05/11] i440fx/acpi: do not add hotplug related amls for cold plugged bridges

[Igor Mammedov]

On Wed, 16 Sep 2020 11:43:29 +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
                                           ^^

thanks&co could be in form Reported-by: Suggested-by: tags at the end

> the current implementaton, windows would try to hot-unplug a pci bridge when
s/windows/Windows/


> 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
s/amls/ACPI code/

the same applies to other patches that mention 'amls'
                                                 
> pci slot where the bridge is cold plugged. We have a demo video here:
> https://youtu.be/pME2sjyQweo

try to not use links in commit message especially ephemeral ones
that tend to disappear with time.
Description in commit message should be sufficient to describe issue.
it's fine to give links under --- line as additional info to support
the case and that gets discarded when patch is applied.

> 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
ditto and fix the same in other patches.

I'd also try format commit message so line length
won't be over 80 characters
 
> 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.

I'd say that also belongs under --- line

> Signed-off-by: Ani Sinha <ani@anisinha.ca>
> ---
>  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;