Re: [edk2-devel] [PATCH] MdeModulePkg/PciBusDxe: Enumerator to check for RCiEP before looking for RP

["Bassa, Damian" <damian.bassa@intel.com>]

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It refers to access to the root port device that doesn't exist in case we are dealing with RCiEP device.
There can be specific case where RCiEP device has ARI extended capability ID (even though it's unsupported in this case).
In such a case PciSearchDevice goes to CreatePciIoDevice through GatherDeviceInfo. And in this case parent is PCI_IO_DEVICE instance created from CreateRootBridge function, which isn't valid PCIe device and doesn't have specific bus, only a range of buses. In that case enumerator tries to use this instance to read operation using default 0 bus number, which isn't correct.

Damian

From: Wu, Hao A <hao.a.wu@intel.com>
Sent: Tuesday, August 31, 2021 6:28 AM
To: devel@edk2.groups.io; Wu, Hao A <hao.a.wu@intel.com>; Bassa, Damian <damian.bassa@intel.com>; Ni, Ray <ray.ni@intel.com>
Subject: RE: [edk2-devel] [PATCH] MdeModulePkg/PciBusDxe: Enumerator to check for RCiEP before looking for RP

From: devel@edk2.groups.io<mailto:devel@edk2.groups.io> <devel@edk2.groups.io<mailto:devel@edk2.groups.io>> On Behalf Of Wu, Hao A
Sent: Tuesday, August 31, 2021 12:25 PM
To: devel@edk2.groups.io<mailto:devel@edk2.groups.io>; Bassa, Damian <damian.bassa@intel.com<mailto:damian.bassa@intel.com>>
Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/PciBusDxe: Enumerator to check for RCiEP before looking for RP

Really sorry,

Could you help to provide more information on the below statement?
"undefined parent register accesses"

Thanks in advance.

Best Regards,
Hao Wu

From: devel@edk2.groups.io<mailto:devel@edk2.groups.io> <devel@edk2.groups.io<mailto:devel@edk2.groups.io>> On Behalf Of Bassa, Damian
Sent: Tuesday, August 24, 2021 11:15 PM
To: devel@edk2.groups.io<mailto:devel@edk2.groups.io>
Subject: [edk2-devel] [PATCH] MdeModulePkg/PciBusDxe: Enumerator to check for RCiEP before looking for RP

Before trying to access parent root port to check ARI capabilities,
enumerator should see if Endpoint device is not Root Complex integrated
to avoid undefined parent register accesses in these cases.

Signed-off-by: Damian Bassa damian.bassa@intel.com<mailto:damian.bassa@intel.com>

---
.../Bus/Pci/PciBusDxe/PciEnumeratorSupport.c         | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
index db1b35f8ef..6451fb8af9 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
@@ -2153,6 +2153,7 @@ CreatePciIoDevice (
   PCI_IO_DEVICE        *PciIoDevice;
   EFI_PCI_IO_PROTOCOL  *PciIo;
   EFI_STATUS           Status;
+  PCI_REG_PCIE_CAPABILITY Capability;

   PciIoDevice = AllocateZeroPool (sizeof (PCI_IO_DEVICE));
   if (PciIoDevice == NULL) {
@@ -2229,7 +2230,16 @@ CreatePciIoDevice (
     return NULL;
   }

-  if (PcdGetBool (PcdAriSupport)) {
+  PciIo->Pci.Read (
+                PciIo,
+                EfiPciIoWidthUint16,
+                PciIoDevice->PciExpressCapabilityOffset + OFFSET_OF (PCI_CAPABILITY_PCIEXP, Capability),
+                1,
+                &Capability.Uint16
+                );
+
+  if (PcdGetBool (PcdAriSupport) &&
+    Capability.Bits.DevicePortType != PCIE_DEVICE_PORT_TYPE_ROOT_COMPLEX_INTEGRATED_ENDPOINT) {
     //
     // Check if the device is an ARI device.
     //
--
2.27.0.windows.1

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