Re: [PATCH v2] MdeModulePkg/EmmcDxe: Make sure no extra data is erased by EraseBlocks

["Zeng, Star" <star.zeng@intel.com>]

Two minor comments, others are good to me.

1. Could the code use (LastLba + 1 - EndGroupLba) instead of (LastLba - EndGroupLba + 1)?

2. Could the code have the debug message "DEBUG ((EFI_D_ERROR, "EmmcEraseBlocks(): Lba 0x%x BlkNo 0x%x Event %p with %r\n", Lba, BlockNum, Token->Event, Status))" for the new return paths the patch added? And the debug level should be DEBUG_INFO instead of EFI_D_ERROR?


Thanks,
Star
-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Hao Wu
Sent: Thursday, August 10, 2017 9:21 AM
To: edk2-devel@lists.01.org
Cc: Wu, Hao A <hao.a.wu@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>; Zeng, Star <star.zeng@intel.com>
Subject: [edk2] [PATCH v2] MdeModulePkg/EmmcDxe: Make sure no extra data is erased by EraseBlocks

V2 changes:

The Trim command is not supported on all eMMC devices. For those devices that do not support such command, add codes to handle the scenario.

Commit message:

The current implementation of the Erase Block Protocol service
EraseBlocks() uses the erase command. According to spec eMMC Electrical Standard 5.1, Section 6.6.9:

The erasable unit of the eMMC is the "Erase Group"; Erase group is measured in write blocks that are the basic writable units of the Device.
...
When the Erase is executed it will apply to all write blocks within an erase group.

However, code logic in function EmmcEraseBlocks() does not check whether the blocks to be erased form complete erase groups. Missing such checks will lead to erasing extra data on the device.

This commit will:
a. If the device support the Trim command, use the Trim command to perform the erase operations for eMMC devices.

According to the spec:
Unlike the Erase command, the Trim function applies the erase operation to write blocks instead of erase groups.

b. If the device does not support the Trim command, use the Erase command to erase the data in the erase groups. And write zeros to those blocks that cannot form a complete erase group.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
---
 MdeModulePkg/Bus/Sd/EmmcDxe/EmmcBlockIo.c | 127 +++++++++++++++++++++++++++++-
 1 file changed, 125 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Bus/Sd/EmmcDxe/EmmcBlockIo.c b/MdeModulePkg/Bus/Sd/EmmcDxe/EmmcBlockIo.c
index c432d26801..916f15d429 100644
--- a/MdeModulePkg/Bus/Sd/EmmcDxe/EmmcBlockIo.c
+++ b/MdeModulePkg/Bus/Sd/EmmcDxe/EmmcBlockIo.c
@@ -1851,6 +1851,14 @@ EmmcEraseBlock (
   EraseBlock->SdMmcCmdBlk.CommandIndex = EMMC_ERASE;
   EraseBlock->SdMmcCmdBlk.CommandType  = SdMmcCommandTypeAc;
   EraseBlock->SdMmcCmdBlk.ResponseType = SdMmcResponseTypeR1b;
+  if ((Device->ExtCsd.SecFeatureSupport & BIT4) != 0) {
+    //
+    // Perform a Trim operation which applies the erase operation to write blocks
+    // instead of erase groups. (Spec JESD84-B51, eMMC Electrical Standard 5.1,
+    // Section 6.6.10 and 6.10.4)
+    //
+    EraseBlock->SdMmcCmdBlk.CommandArgument = 1;  }
 
   EraseBlock->IsEnd = IsEnd;
   EraseBlock->Token = Token;
@@ -1903,6 +1911,43 @@ Error:
 }
 
 /**
+  Write zeros to specified blocks.
+
+  @param[in]  Partition         A pointer to the EMMC_PARTITION instance.
+  @param[in]  StartLba          The starting logical block address to write zeros.
+  @param[in]  Size              The size in bytes to fill with zeros. This must be a multiple of
+                                the physical block size of the device.
+
+  @retval EFI_SUCCESS           The request is executed successfully.
+  @retval EFI_OUT_OF_RESOURCES  The request could not be executed due to a lack of resources.
+  @retval Others                The request could not be executed successfully.
+
+**/
+EFI_STATUS
+EmmcWriteZeros (
+  IN  EMMC_PARTITION            *Partition,
+  IN  EFI_LBA                   StartLba,
+  IN  UINTN                     Size
+  )
+{
+  EFI_STATUS                           Status;
+  UINT8                                *Buffer;
+  UINT32                               MediaId;
+
+  Buffer = AllocateZeroPool (Size);
+  if (Buffer == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  MediaId = Partition->BlockMedia.MediaId;
+
+  Status = EmmcReadWrite (Partition, MediaId, StartLba, Buffer, Size, 
+ FALSE, NULL);  FreePool (Buffer);
+
+  return Status;
+}
+
+/**
   Erase a specified number of device blocks.
 
   @param[in]       This           Indicates a pointer to the calling context.
@@ -1943,7 +1988,13 @@ EmmcEraseBlocks (
   EFI_BLOCK_IO_MEDIA                    *Media;
   UINTN                                 BlockSize;
   UINTN                                 BlockNum;
+  EFI_LBA                               FirstLba;
   EFI_LBA                               LastLba;
+  EFI_LBA                               StartGroupLba;
+  EFI_LBA                               EndGroupLba;
+  UINT32                                EraseGroupSize;
+  UINT32                                Remainder;
+  UINTN                                 WriteZeroSize;
   UINT8                                 PartitionConfig;
   EMMC_PARTITION                        *Partition;
   EMMC_DEVICE                           *Device;
@@ -1978,7 +2029,8 @@ EmmcEraseBlocks (
     Token->TransactionStatus = EFI_SUCCESS;
   }
 
-  LastLba = Lba + BlockNum - 1;
+  FirstLba = Lba;
+  LastLba  = Lba + BlockNum - 1;
 
   //
   // Check if needs to switch partition access.
@@ -1994,7 +2046,78 @@ EmmcEraseBlocks (
     Device->ExtCsd.PartitionConfig = PartitionConfig;
   }
 
-  Status = EmmcEraseBlockStart (Partition, Lba, (EFI_BLOCK_IO2_TOKEN*)Token, FALSE);
+  if ((Device->ExtCsd.SecFeatureSupport & BIT4) == 0) {
+    //
+    // If the Trim operation is not supported by the device, handle the erase
+    // of blocks that do not form a complete erase group separately.
+    //
+    EraseGroupSize = This->EraseLengthGranularity;
+
+    DivU64x32Remainder (FirstLba, EraseGroupSize, &Remainder);
+    StartGroupLba = (Remainder == 0) ? FirstLba : (FirstLba + 
+ EraseGroupSize - Remainder);
+
+    DivU64x32Remainder (LastLba + 1, EraseGroupSize, &Remainder);
+    EndGroupLba = LastLba + 1 - Remainder;
+
+    //
+    // If the size to erase is smaller than the erase group size, the whole
+    // erase operation is performed by writting zeros.
+    //
+    if (BlockNum < EraseGroupSize) {
+      Status = EmmcWriteZeros (Partition, FirstLba, Size);
+      if (EFI_ERROR (Status)) {
+        return Status;
+      }
+
+      if ((Token != NULL) && (Token->Event != NULL)) {
+        Token->TransactionStatus = EFI_SUCCESS;
+        gBS->SignalEvent (Token->Event);
+      }
+      return EFI_SUCCESS;
+    }
+
+    //
+    // If the starting LBA to erase is not aligned with the start of an erase
+    // group, write zeros to erase the data from starting LBA to the end of the
+    // current erase group.
+    //
+    if (StartGroupLba > FirstLba) {
+      WriteZeroSize = (UINTN)(StartGroupLba - FirstLba) * BlockSize;
+      Status = EmmcWriteZeros (Partition, FirstLba, WriteZeroSize);
+      if (EFI_ERROR (Status)) {
+        return Status;
+      }
+    }
+
+    //
+    // If the ending LBA to erase is not aligned with the end of an erase
+    // group, write zeros to erase the data from the start of the erase group
+    // to the ending LBA.
+    //
+    if (EndGroupLba <= LastLba) {
+      WriteZeroSize = (UINTN)(LastLba - EndGroupLba + 1) * BlockSize;
+      Status = EmmcWriteZeros (Partition, EndGroupLba, WriteZeroSize);
+      if (EFI_ERROR (Status)) {
+        return Status;
+      }
+    }
+
+    //
+    // Check whether there is erase group to erase.
+    //
+    if (EndGroupLba <= StartGroupLba) {
+      if ((Token != NULL) && (Token->Event != NULL)) {
+        Token->TransactionStatus = EFI_SUCCESS;
+        gBS->SignalEvent (Token->Event);
+      }
+      return EFI_SUCCESS;
+    }
+
+    FirstLba = StartGroupLba;
+    LastLba  = EndGroupLba - 1;
+  }
+
+  Status = EmmcEraseBlockStart (Partition, FirstLba, 
+ (EFI_BLOCK_IO2_TOKEN*)Token, FALSE);
   if (EFI_ERROR (Status)) {
     return Status;
   }
--
2.12.0.windows.1

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