From 6a2b20ff97e4256970644a07f74a4c5655bf5072 Mon Sep 17 00:00:00 2001
From: "Jeff Brasen via groups.io" <jbrasen=nvidia.com@groups.io>
Date: Mon, 14 Feb 2022 18:45:31 +0000
Subject: [PATCH] MdeModulePkg/NonDiscoverablePciDeviceDxe: Allow partial
 FreeBuffer

Add support for partial free of non cached buffers.
If a request for less than the full size is requested new allocations
for the remaining head and tail of the buffer are added to the list.
Added verification that Buffer is EFI_PAGE_SIZE aligned.
The XHCI driver does this if the page size for the controller is >4KB.

Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>
Acked-by: Liming Gao <gaoliming@byosoft.com.cn>
---
 .../NonDiscoverablePciDeviceIo.c              | 64 ++++++++++++++++++-
 1 file changed, 62 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c
index c1c5c6267c..2fb78d8f96 100644
--- a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c
+++ b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c
@@ -960,13 +960,25 @@ NonCoherentPciIoFreeBuffer (
   LIST_ENTRY                                   *Entry;
   EFI_STATUS                                   Status;
   NON_DISCOVERABLE_DEVICE_UNCACHED_ALLOCATION  *Alloc;
+  NON_DISCOVERABLE_DEVICE_UNCACHED_ALLOCATION  *AllocHead;
+  NON_DISCOVERABLE_DEVICE_UNCACHED_ALLOCATION  *AllocTail;
   BOOLEAN                                      Found;
+  UINTN                                        StartPages;
+  UINTN                                        EndPages;
+
+  if (HostAddress != ALIGN_POINTER (HostAddress, EFI_PAGE_SIZE)) {
+    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
+    return EFI_INVALID_PARAMETER;
+  }
 
   Dev = NON_DISCOVERABLE_PCI_DEVICE_FROM_PCI_IO (This);
 
   Found = FALSE;
   Alloc = NULL;
 
+  AllocHead = NULL;
+  AllocTail = NULL;
+
   //
   // Find the uncached allocation list entry associated
   // with this allocation
@@ -976,9 +988,19 @@ NonCoherentPciIoFreeBuffer (
        Entry = Entry->ForwardLink)
   {
     Alloc = BASE_CR (Entry, NON_DISCOVERABLE_DEVICE_UNCACHED_ALLOCATION, List);
-    if ((Alloc->HostAddress == HostAddress) && (Alloc->NumPages == Pages)) {
+
+    StartPages = 0;
+    if (Alloc->HostAddress < HostAddress) {
+      StartPages = EFI_SIZE_TO_PAGES (
+                     (UINTN)HostAddress - (UINTN)Alloc->HostAddress
+                     );
+    }
+
+    if ((Alloc->HostAddress <= HostAddress) &&
+        (Alloc->NumPages >= (Pages + StartPages)))
+    {
       //
-      // We are freeing the exact allocation we were given
+      // We are freeing at least part of what we were given
       // before by AllocateBuffer()
       //
       Found = TRUE;
@@ -991,7 +1013,45 @@ NonCoherentPciIoFreeBuffer (
     return EFI_NOT_FOUND;
   }
 
+  EndPages = Alloc->NumPages - (Pages + StartPages);
+
+  if (StartPages != 0) {
+    AllocHead = AllocatePool (sizeof *AllocHead);
+    if (AllocHead == NULL) {
+      return EFI_OUT_OF_RESOURCES;
+    }
+
+    AllocHead->HostAddress = Alloc->HostAddress;
+
+    AllocHead->NumPages   = StartPages;
+    AllocHead->Attributes = Alloc->Attributes;
+  }
+
+  if (EndPages != 0) {
+    AllocTail = AllocatePool (sizeof *AllocTail);
+    if (AllocTail == NULL) {
+      return EFI_OUT_OF_RESOURCES;
+    }
+
+    AllocTail->HostAddress = (UINT8 *)Alloc->HostAddress +
+                             EFI_PAGES_TO_SIZE (Pages + StartPages);
+
+    AllocTail->NumPages   = EndPages;
+    AllocTail->Attributes = Alloc->Attributes;
+  }
+
   RemoveEntryList (&Alloc->List);
+  //
+  // Record this new sub allocations in the linked list, so we
+  // can restore the memory space attributes later
+  //
+  if (AllocHead != NULL) {
+    InsertHeadList (&Dev->UncachedAllocationList, &AllocHead->List);
+  }
+
+  if (AllocTail != NULL) {
+    InsertHeadList (&Dev->UncachedAllocationList, &AllocTail->List);
+  }
 
   Status = gDS->SetMemorySpaceAttributes (
                   (EFI_PHYSICAL_ADDRESS)(UINTN)HostAddress,
-- 
2.39.2