Re: [Xen-devel] [PATCH v3 3/3] OvmfPkg/XenSupport: turn off address decoding before BAR sizing

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Fri, Apr 26, 2019 at 08:15:07PM +0200, Laszlo Ersek wrote:
> On 04/25/19 22:23, Igor Druzhinin wrote:
> > On Xen, hvmloader firmware leaves address decoding enabled for
> > enumerated PCI device before jumping into OVMF. OVMF seems to
> > expect it to be disabled and tries to size PCI BARs in several places
> > without disabling it which causes BAR64, for example, being
> > incorrectly placed by QEMU.
> > 
> > Fix it by disabling PCI address decoding explicitly before the
> > first attempt to size BARs on Xen.
> > 
> > Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
> > ---
> > Changes in v3:
> > - dropped unused arguments and rename PcatPciRootBridgeDecoding function
> > - make mask application more clear as suggested
> > ---
> >  OvmfPkg/Library/PciHostBridgeLib/XenSupport.c | 21 +++++++++++++++++++++
> >  1 file changed, 21 insertions(+)
> > 
> > diff --git a/OvmfPkg/Library/PciHostBridgeLib/XenSupport.c 
> > b/OvmfPkg/Library/PciHostBridgeLib/XenSupport.c
> > index 76fca53..b41bd6b 100644
> > --- a/OvmfPkg/Library/PciHostBridgeLib/XenSupport.c
> > +++ b/OvmfPkg/Library/PciHostBridgeLib/XenSupport.c
> > @@ -49,6 +49,22 @@ PcatPciRootBridgeBarExisted (
> >    EnableInterrupts ();
> >  }
> >  
> > +#define PCI_COMMAND_DECODE ((UINT16)(EFI_PCI_COMMAND_IO_SPACE | \
> > +                                     EFI_PCI_COMMAND_MEMORY_SPACE))
> > +STATIC
> > +VOID
> > +PcatPciRootBridgeDecodingDisable (
> > +  IN  UINTN                          Address
> > +  )
> > +{
> > +  UINT16                             Value;
> > +
> > +  Value = PciRead16 (Address);
> > +  if (Value & PCI_COMMAND_DECODE) {
> > +    PciWrite16 (Address, Value & ~(UINT32)PCI_COMMAND_DECODE);
> > +  }
> > +}
> > +
> >  STATIC
> >  VOID
> >  PcatPciRootBridgeParseBars (
> > @@ -75,6 +91,11 @@ PcatPciRootBridgeParseBars (
> >    UINT64                            Limit;
> >    PCI_ROOT_BRIDGE_APERTURE          *MemAperture;
> >  
> > +  // Disable address decoding for every device before OVMF starts sizing it
> > +  PcatPciRootBridgeDecodingDisable (
> > +    PCI_LIB_ADDRESS (Bus, Device, Function, PCI_COMMAND_OFFSET)
> > +  );
> > +
> >    for (Offset = BarOffsetBase; Offset < BarOffsetEnd; Offset += sizeof 
> > (UINT32)) {
> >      PcatPciRootBridgeBarExisted (
> >        PCI_LIB_ADDRESS (Bus, Device, Function, Offset),
> > 
> 
> Acked-by: Laszlo Ersek <lersek@xxxxxxxxxx>
> 
> Someone from the Xen community please ACK this too, and then we can push
> the series.

Acked-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

Thanks,

-- 
Anthony PERARD

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