[PATCH 3/3] MdeModulePkg/Bus/Pci/XhciDxe: Check port is compatible before getting PSIV

["Sean Rhodes" <sean@starlabs.systems>]

On some platforms, including Sky Lake and Kaby Lake, the PSIV (Protocol
Speed ID Value) indices are shared between Protocol Speed ID DWORD' in
the extended capabilities registers for both USB2 (Full Speed) and USB3
(Super Speed).

An example can be found below:

    XhcCheckUsbPortSpeedUsedPsic: checking for USB2 ext caps
    XhciPsivGetPsid: found 3 PSID entries
    XhciPsivGetPsid: looking for port speed 1
    XhciPsivGetPsid: PSIV 1 PSIE 2 PLT 0 PSIM 12
    XhciPsivGetPsid: PSIV 2 PSIE 1 PLT 0 PSIM 1500
    XhciPsivGetPsid: PSIV 3 PSIE 2 PLT 0 PSIM 480
    XhcCheckUsbPortSpeedUsedPsic: checking for USB3 ext caps
    XhciPsivGetPsid: found 3 PSID entries
    XhciPsivGetPsid: looking for port speed 1
    XhciPsivGetPsid: PSIV 1 PSIE 3 PLT 0 PSIM 5
    XhciPsivGetPsid: PSIV 2 PSIE 3 PLT 0 PSIM 10
    XhciPsivGetPsid: PSIV 34 PSIE 2 PLT 0 PSIM 1248

The result is edk2 detecting USB2 devices as USB3 devices, which
consequently causes enumeration to fail.

To avoid incorrect detection, check the Compatible Port Offset to find
the starting Port of Root Hubs that support the protocol.

Signed-off-by: Sean Rhodes <sean@starlabs.systems>
---
 MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c    |  2 +-
 MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c | 35 +++++++++++++++++++++-----
 MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.h |  8 +++---
 3 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
index 8dd7a8fbb7..461b2cd9b5 100644
--- a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
+++ b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
@@ -405,7 +405,7 @@ XhcGetRootHubPortStatus (
   // Section 7.2 xHCI Support Protocol Capability
   //
   if (PortSpeed > 0) {
-    PortStatus->PortStatus = XhcCheckUsbPortSpeedUsedPsic (Xhc, PortSpeed);
+    PortStatus->PortStatus = XhcCheckUsbPortSpeedUsedPsic (Xhc, PortSpeed, PortNumber);
     // If no match found in ext cap reg, fall back to PORTSC
     if (PortStatus->PortStatus == 0) {
       //
diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c b/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
index 2b4a4b2444..5700fc5fb8 100644
--- a/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
+++ b/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
@@ -636,6 +636,7 @@ XhcGetSupportedProtocolCapabilityAddr (
   @param  Xhc            The XHCI Instance.
   @param  ExtCapOffset   The USB Major Version in xHCI Support Protocol Capability Field
   @param  PortSpeed      The Port Speed Field in USB PortSc register
+  @param  PortNumber     The Port Number (0-indexed)
 
   @return The Protocol Speed ID (PSI) from xHCI Supported Protocol capability register.
 
@@ -644,12 +645,15 @@ UINT32
 XhciPsivGetPsid (
   IN USB_XHCI_INSTANCE  *Xhc,
   IN UINT32             ExtCapOffset,
-  IN UINT8              PortSpeed
+  IN UINT8              PortSpeed,
+  IN UINT8              PortNumber
   )
 {
   XHC_SUPPORTED_PROTOCOL_DW2                PortId;
   XHC_SUPPORTED_PROTOCOL_PROTOCOL_SPEED_ID  Reg;
   UINT32                                    Count;
+  UINT32                                    MinPortIndex;
+  UINT32                                    MaxPortIndex;
 
   if ((Xhc == NULL) || (ExtCapOffset == 0xFFFFFFFF)) {
     return 0;
@@ -663,6 +667,23 @@ XhciPsivGetPsid (
   //
   PortId.Dword = XhcReadExtCapReg (Xhc, ExtCapOffset + XHC_SUPPORTED_PROTOCOL_DW2_OFFSET);
 
+  //
+  // According to XHCI 1.1 spec November 2017, valid values
+  // for CompPortOffset are 1 to CompPortCount - 1.
+  //
+  // PortNumber is zero-indexed, so subtract 1.
+  //
+  if ((PortId.Data.CompPortOffset == 0) || (PortId.Data.CompPortCount == 0)) {
+    return 0;
+  }
+
+  MinPortIndex = PortId.Data.CompPortOffset - 1;
+  MaxPortIndex = MinPortIndex + PortId.Data.CompPortCount - 1;
+
+  if ((PortNumber < MinPortIndex) || (PortNumber > MaxPortIndex)) {
+    return 0;
+  }
+
   for (Count = 0; Count < PortId.Data.Psic; Count++) {
     Reg.Dword = XhcReadExtCapReg (Xhc, ExtCapOffset + XHC_SUPPORTED_PROTOCOL_PSI_OFFSET + (Count << 2));
     if (Reg.Data.Psiv == PortSpeed) {
@@ -676,8 +697,9 @@ XhciPsivGetPsid (
 /**
   Find PortSpeed value match case in XHCI Supported Protocol Capability
 
-  @param  Xhc        The XHCI Instance.
-  @param  PortSpeed  The Port Speed Field in USB PortSc register
+  @param  Xhc         The XHCI Instance.
+  @param  PortSpeed   The Port Speed Field in USB PortSc register
+  @param  PortNumber  The Port Number (0-indexed)
 
   @return The USB Port Speed.
 
@@ -685,7 +707,8 @@ XhciPsivGetPsid (
 UINT16
 XhcCheckUsbPortSpeedUsedPsic (
   IN USB_XHCI_INSTANCE  *Xhc,
-  IN UINT8              PortSpeed
+  IN UINT8              PortSpeed,
+  IN UINT8              PortNumber
   )
 {
   XHC_SUPPORTED_PROTOCOL_PROTOCOL_SPEED_ID  SpField;
@@ -703,7 +726,7 @@ XhcCheckUsbPortSpeedUsedPsic (
   // PortSpeed definition when the Major Revision is 03h.
   //
   if (Xhc->Usb3SupOffset != 0xFFFFFFFF) {
-    SpField.Dword = XhciPsivGetPsid (Xhc, Xhc->Usb3SupOffset, PortSpeed);
+    SpField.Dword = XhciPsivGetPsid (Xhc, Xhc->Usb3SupOffset, PortSpeed, PortNumber);
     if (SpField.Dword != 0) {
       //
       // Found the corresponding PORTSC value in PSIV field of USB3 offset.
@@ -717,7 +740,7 @@ XhcCheckUsbPortSpeedUsedPsic (
   // PortSpeed definition when the Major Revision is 02h.
   //
   if ((UsbSpeedIdMap == 0) && (Xhc->Usb2SupOffset != 0xFFFFFFFF)) {
-    SpField.Dword = XhciPsivGetPsid (Xhc, Xhc->Usb2SupOffset, PortSpeed);
+    SpField.Dword = XhciPsivGetPsid (Xhc, Xhc->Usb2SupOffset, PortSpeed, PortNumber);
     if (SpField.Dword != 0) {
       //
       // Found the corresponding PORTSC value in PSIV field of USB2 offset.
diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.h b/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.h
index 5fe2ba4f0e..2e4f95f8ac 100644
--- a/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.h
+++ b/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.h
@@ -623,8 +623,9 @@ XhcGetSupportedProtocolCapabilityAddr (
 /**
   Find SpeedField value match with Port Speed ID value.
 
-  @param  Xhc    The XHCI Instance.
-  @param  Speed  The Port Speed filed in USB PortSc register
+  @param  Xhc         The XHCI Instance.
+  @param  Speed       The Port Speed filed in USB PortSc register
+  @param  PortNumber  The Port Number (0-indexed)
 
   @return The USB Port Speed.
 
@@ -632,7 +633,8 @@ XhcGetSupportedProtocolCapabilityAddr (
 UINT16
 XhcCheckUsbPortSpeedUsedPsic (
   IN USB_XHCI_INSTANCE  *Xhc,
-  IN UINT8              Speed
+  IN UINT8              Speed,
+  IN UINT8              PortNumber
   );
 
 #endif
-- 
2.37.2