[PATCH edk2-platforms v2 1/2] Silicon/SynQuacerPlatformFlashAccessLib: relax FV address check

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

In commit 913fdda9f4b9 ("Silicon/SynQuacerPlatformFlashAccessLib: don't
dereference FVB header fields"), we dropped all accesses to FVB header
field, which was necessary because the flash partition may not in fact
contain such a header. Instead, only an exact match on the base address
of the FV compared to the base address of the capsule payload would
result in a match, making it difficult to create capsules that only
update a subset of the flash contents.

Given that the FVB protocol provides a GetBlockSize() method that also
returns the number of consecutive blocks of that size, and does not rely
on the FVB header contents, we can actually infer the size of the flash
partition, and use it to decide whether a capsule payload targets an
area that is covered by this partition entirely.

This optimization allows us to extend the FV description to include the
SCP firmware partition without requiring us to actually provide a
payload for that partition immediately, which is useful as a preparatory
step.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 Silicon/Socionext/SynQuacer/Library/SynQuacerPlatformFlashAccessLib/SynQuacerPlatformFlashAccessLib.c | 56 ++++++++++----------
 1 file changed, 27 insertions(+), 29 deletions(-)

diff --git a/Silicon/Socionext/SynQuacer/Library/SynQuacerPlatformFlashAccessLib/SynQuacerPlatformFlashAccessLib.c b/Silicon/Socionext/SynQuacer/Library/SynQuacerPlatformFlashAccessLib/SynQuacerPlatformFlashAccessLib.c
index 48d385993b38..51bf9f62457f 100644
--- a/Silicon/Socionext/SynQuacer/Library/SynQuacerPlatformFlashAccessLib/SynQuacerPlatformFlashAccessLib.c
+++ b/Silicon/Socionext/SynQuacer/Library/SynQuacerPlatformFlashAccessLib/SynQuacerPlatformFlashAccessLib.c
@@ -45,8 +45,10 @@ STATIC
 EFI_STATUS
 GetFvbByAddress (
   IN  EFI_PHYSICAL_ADDRESS                Address,
+  IN  UINTN                               Length,
   OUT EFI_FIRMWARE_VOLUME_BLOCK_PROTOCOL  **OutFvb,
-  OUT EFI_PHYSICAL_ADDRESS                *FvbBaseAddress
+  OUT EFI_LBA                             *Lba,
+  OUT UINTN                               *BlockSize
   )
 {
   EFI_STATUS                          Status;
@@ -55,6 +57,8 @@ GetFvbByAddress (
   UINTN                               Index;
   EFI_FIRMWARE_VOLUME_BLOCK_PROTOCOL  *Fvb;
   EFI_FVB_ATTRIBUTES_2                Attributes;
+  EFI_PHYSICAL_ADDRESS                FvbBaseAddress;
+  UINTN                               NumberOfBlocks;
 
   //
   // Locate all handles with Firmware Volume Block protocol
@@ -85,7 +89,7 @@ GetFvbByAddress (
     //
     // Checks if the address range of this handle contains parameter Address
     //
-    Status = Fvb->GetPhysicalAddress (Fvb, FvbBaseAddress);
+    Status = Fvb->GetPhysicalAddress (Fvb, &FvbBaseAddress);
     if (EFI_ERROR (Status)) {
       continue;
     }
@@ -103,9 +107,27 @@ GetFvbByAddress (
       continue;
     }
 
-    if (Address == *FvbBaseAddress) {
+    Status = Fvb->GetBlockSize (Fvb, 0, BlockSize, &NumberOfBlocks);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_INFO, "%a: failed to get FVB blocksize - %r, ignoring\n",
+        __FUNCTION__, Status));
+      continue;
+    }
+
+    if ((Length % *BlockSize) != 0) {
+      DEBUG ((DEBUG_INFO,
+        "%a: Length 0x%lx is not a multiple of the blocksize 0x%lx, ignoring\n",
+        __FUNCTION__, Length, *BlockSize));
+      Status = EFI_INVALID_PARAMETER;
+      continue;
+    }
+
+    if ((Address >= FvbBaseAddress) &&
+        ((Address + Length) <=
+         (FvbBaseAddress + (*BlockSize * NumberOfBlocks)))) {
       *OutFvb  = Fvb;
-      Status   = EFI_SUCCESS;
+      *Lba = (Address - FvbBaseAddress) / *BlockSize;
+      Status = EFI_SUCCESS;
       break;
     }
 
@@ -191,9 +213,7 @@ PerformFlashWriteWithProgress (
   EFI_FIRMWARE_VOLUME_BLOCK_PROTOCOL  *Fvb;
   EFI_STATUS                          Status;
   UINTN                               BlockSize;
-  UINTN                               NumberOfBlocks;
   EFI_LBA                             Lba;
-  EFI_PHYSICAL_ADDRESS                FvbBaseAddress;
   UINTN                               NumBytes;
   EFI_GRAPHICS_OUTPUT_BLT_PIXEL_UNION Black;
   EFI_GRAPHICS_OUTPUT_BLT_PIXEL_UNION White;
@@ -227,7 +247,7 @@ PerformFlashWriteWithProgress (
   // that covers the system firmware
   //
   Fvb = NULL;
-  Status = GetFvbByAddress (FlashAddress, &Fvb, &FvbBaseAddress);
+  Status = GetFvbByAddress (FlashAddress, Length, &Fvb, &Lba, &BlockSize);
   if (EFI_ERROR (Status)) {
     DEBUG ((DEBUG_ERROR,
       "%a: failed to locate FVB handle for address 0x%llx - %r\n",
@@ -235,28 +255,6 @@ PerformFlashWriteWithProgress (
     return Status;
   }
 
-  Status = Fvb->GetBlockSize(Fvb, 0, &BlockSize, &NumberOfBlocks);
-  if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_ERROR, "%a: failed to get FVB blocksize - %r\n",
-      __FUNCTION__, Status));
-    return Status;
-  }
-
-  if ((Length % BlockSize) != 0) {
-    DEBUG ((DEBUG_ERROR,
-      "%a: Length 0x%lx is not a multiple of the blocksize 0x%lx\n",
-      __FUNCTION__, Length, BlockSize));
-    return EFI_INVALID_PARAMETER;
-  }
-
-  Lba = (FlashAddress - FvbBaseAddress) / BlockSize;
-  if (Lba > NumberOfBlocks - 1) {
-    DEBUG ((DEBUG_ERROR,
-      "%a: flash device with non-uniform blocksize not supported\n",
-      __FUNCTION__));
-    return EFI_UNSUPPORTED;
-  }
-
   //
   // Remap the region as device rather than uncached.
   //
-- 
2.17.1