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Subject: Re: [edk2-devel] [PATCH v3 3/3] OvmfPkg/XenSupport: turn off address decoding before BAR sizing
To: devel@edk2.groups.io, anthony.perard@citrix.com
Cc: Igor Druzhinin <igor.druzhinin@citrix.com>, jordan.l.justen@intel.com,
 ard.biesheuvel@linaro.org, julien.grall@arm.com,
 xen-devel@lists.xenproject.org
References: <1556223838-5176-1-git-send-email-igor.druzhinin@citrix.com>
 <1556223838-5176-4-git-send-email-igor.druzhinin@citrix.com>
 <b999513b-b843-e440-d1f2-c49589506a65@redhat.com>
 <20190430163551.GA1264@perard.uk.xensource.com>
From: "Laszlo Ersek" <lersek@redhat.com>
Message-ID: <c397c8a4-4a97-7e57-8233-6bb5632e40d8@redhat.com>
Date: Tue, 30 Apr 2019 18:48:44 +0200
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On 04/30/19 18:35, Anthony PERARD wrote:
> 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@citrix.com>
>>> ---
>>> 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@redhat.com>
>>
>> Someone from the Xen community please ACK this too, and then we can push
>> the series.
> 
> Acked-by: Anthony PERARD <anthony.perard@citrix.com>

Series pushed as commit range 9fb2ce2f465d..0c40c9c925ca.

Thanks
Laszlo