Re: [edk2-devel] [PATCH 1/1] OvmfPkg/PciHotPlugInitDxe: fix io window size

["Yao, Jiewen" <jiewen.yao@intel.com>]

Maybe it should be done in PciHostBridge driver, because PciBus is generic and PciHostBridge knows the smallest windows size for this platform.



> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Yao,
> Jiewen
> Sent: Friday, December 9, 2022 3:28 PM
> To: devel@edk2.groups.io; kraxel@redhat.com
> Cc: Oliver Steffen <osteffen@redhat.com>; Pawel Polawski
> <ppolawsk@redhat.com>; Ard Biesheuvel <ardb+tianocore@kernel.org>;
> Justen, Jordan L <jordan.l.justen@intel.com>
> Subject: Re: [edk2-devel] [PATCH 1/1] OvmfPkg/PciHotPlugInitDxe: fix io
> window size
> 
> Uhmm. I assume this should be done in PciBus driver.
> It will be a burden to let each PciHotPlugInitDxe to fix the smallest IO
> window.
> 
> + PciBus maintainer: Ray Ni <ray.ni@intel.com> and Hao A Wu
> <hao.a.wu@intel.com>
> What's your opinion?
> 
> 
> > -----Original Message-----
> > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Gerd
> > Hoffmann
> > Sent: Monday, November 28, 2022 2:26 PM
> > To: devel@edk2.groups.io
> > Cc: Oliver Steffen <osteffen@redhat.com>; Gerd Hoffmann
> > <kraxel@redhat.com>; Pawel Polawski <ppolawsk@redhat.com>; Ard
> > Biesheuvel <ardb+tianocore@kernel.org>; Justen, Jordan L
> > <jordan.l.justen@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>
> > Subject: [edk2-devel] [PATCH 1/1] OvmfPkg/PciHotPlugInitDxe: fix io
> > window size
> >
> > Smallest IO window size for PCI bridges is 0x1000.  Add a check and
> > fixup the Exponent of needed.  Avoids broken resource assignments
> > like this:
> >
> >     [ ... ]
> >     PciBus: Resource Map for Root Bridge PciRoot(0x0)
> >     Type =   Io16; Base = 0x6000;   Length = 0x7000;        Alignment = 0xFFF
> >     [ ... ]
> >        Base = 0xC000;       Length = 0x200; Alignment = 0xFFF;      Owner =
> PPB
> > [00|02|00:**]
> >        Base = 0xC200;       Length = 0x40;  Alignment = 0x3F;       Owner = PCI
> > [00|1F|03:20]
> >        Base = 0xC240;       Length = 0x20;  Alignment = 0x1F;       Owner = PCI
> > [00|1F|02:20]
> >     [ ... ]
> >
> > ... which the linux kernel fixes up later:
> >
> >     [    0.644657] pci 0000:00:1f.3: BAR 4: assigned [io  0x1000-0x103f]
> >     [    0.646833] pci 0000:00:1f.2: BAR 4: assigned [io  0x1040-0x105f]
> >
> > With the patch applied:
> >
> >     { ... ]
> >     PciBus: Resource Map for Root Bridge PciRoot(0x0)
> >     Type =   Io16; Base = 0x6000;   Length = 0x8000;        Alignment = 0xFFF
> >     [ ... ]
> >        Base = 0xC000;       Length = 0x1000;        Alignment = 0xFFF;
> Owner
> > = PPB [00|02|00:**]
> >        Base = 0xD000;       Length = 0x40;  Alignment = 0x3F;       Owner = PCI
> > [00|1F|03:20]
> >        Base = 0xD040;       Length = 0x20;  Alignment = 0x1F;       Owner = PCI
> > [00|1F|02:20]
> >     [ ... ]
> >
> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> > ---
> >  OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.c
> > b/OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.c
> > index 3f9c84cf2b54..6c8bbc3b199d 100644
> > --- a/OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.c
> > +++ b/OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.c
> > @@ -117,6 +117,10 @@ SetIoPadding (
> >    IN     UINTN                              SizeExponent
> >    )
> >  {
> > +  if (SizeExponent < 12) {
> > +    SizeExponent = 12;
> > +  }
> > +
> >    Descriptor->ResType      = ACPI_ADDRESS_SPACE_TYPE_IO;
> >    Descriptor->AddrLen      = LShiftU64 (1, SizeExponent);
> >    Descriptor->AddrRangeMax = Descriptor->AddrLen - 1;
> > --
> > 2.38.1
> >
> >
> >
> >
> >
> 
> 
> 
> 
>