[PATCH 09/13] OvmfPkg/BaseMemEncryptSevLib: introduce MemEncryptSevClearMmioPageEncMask()

["Brijesh Singh" <brijesh.singh@amd.com>]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

The MemEncryptSevClearMmioPageEncMask() helper can be used for clearing
the memory encryption mask for the Mmio region.

The MemEncryptSevClearMmioPageEncMask() is a simplifies version of
MemEncryptSevClearPageEncMask() -- it does not flush the caches after
clearing the page encryption mask.

Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/Include/Library/MemEncryptSevLib.h    | 25 ++++++++++++++
 .../BaseMemEncryptSevLib/X64/VirtualMemory.h  | 23 +++++++++++++
 .../Ia32/MemEncryptSevLib.c                   | 31 +++++++++++++++++
 .../X64/MemEncryptSevLib.c                    | 33 +++++++++++++++++++
 .../X64/PeiDxeVirtualMemory.c                 | 33 +++++++++++++++++++
 5 files changed, 145 insertions(+)

diff --git a/OvmfPkg/Include/Library/MemEncryptSevLib.h b/OvmfPkg/Include/Library/MemEncryptSevLib.h
index 99f15a7d1271..b91490d5d44d 100644
--- a/OvmfPkg/Include/Library/MemEncryptSevLib.h
+++ b/OvmfPkg/Include/Library/MemEncryptSevLib.h
@@ -203,4 +203,29 @@ MemEncryptSevGetAddressRangeState (
   IN UINTN                    Length
   );
 
+/**
+  This function clears memory encryption bit for the MMIO region specified by
+  BaseAddress and NumPages.
+
+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use
+                                      current CR3)
+  @param[in]  BaseAddress             The physical address that is the start
+                                      address of a MMIO region.
+  @param[in]  NumPages                The number of pages from start memory
+                                      region.
+
+  @retval RETURN_SUCCESS              The attributes were cleared for the
+                                      memory region.
+  @retval RETURN_INVALID_PARAMETER    Number of pages is zero.
+  @retval RETURN_UNSUPPORTED          Clearing the memory encryption attribute
+                                      is not supported
+**/
+RETURN_STATUS
+EFIAPI
+MemEncryptSevClearMmioPageEncMask (
+  IN PHYSICAL_ADDRESS         Cr3BaseAddress,
+  IN PHYSICAL_ADDRESS         BaseAddress,
+  IN UINTN                    NumPages
+  );
+
 #endif // _MEM_ENCRYPT_SEV_LIB_H_
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.h b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.h
index fe2a0b2826cd..8dc39e647b90 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.h
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.h
@@ -126,4 +126,27 @@ InternalMemEncryptSevGetAddressRangeState (
   IN UINTN                    Length
   );
 
+/**
+  This function clears memory encryption bit for the MMIO region specified by
+  PhysicalAddress and Length.
+
+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use
+                                      current CR3)
+  @param[in]  PhysicalAddress         The physical address that is the start
+                                      address of a MMIO region.
+  @param[in]  Length                  The length of memory region
+
+  @retval RETURN_SUCCESS              The attributes were cleared for the
+                                      memory region.
+  @retval RETURN_INVALID_PARAMETER    Length is zero.
+  @retval RETURN_UNSUPPORTED          Clearing the memory encyrption attribute
+                                      is not supported
+**/
+RETURN_STATUS
+EFIAPI
+InternalMemEncryptSevClearMmioPageEncMask (
+  IN  PHYSICAL_ADDRESS        Cr3BaseAddress,
+  IN  PHYSICAL_ADDRESS        PhysicalAddress,
+  IN  UINTN                   Length
+  );
 #endif
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c b/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c
index 12a5bf495bd7..169d3118e44f 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c
@@ -111,3 +111,34 @@ MemEncryptSevGetAddressRangeState (
   //
   return MemEncryptSevAddressRangeEncrypted;
 }
+
+/**
+  This function clears memory encryption bit for the MMIO region specified by
+  BaseAddress and NumPages.
+
+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use
+                                      current CR3)
+  @param[in]  BaseAddress             The physical address that is the start
+                                      address of a MMIO region.
+  @param[in]  NumPages                The number of pages from start memory
+                                      region.
+
+  @retval RETURN_SUCCESS              The attributes were cleared for the
+                                      memory region.
+  @retval RETURN_INVALID_PARAMETER    Number of pages is zero.
+  @retval RETURN_UNSUPPORTED          Clearing the memory encryption attribute
+                                      is not supported
+**/
+RETURN_STATUS
+EFIAPI
+MemEncryptSevClearMmioPageEncMask (
+  IN PHYSICAL_ADDRESS         Cr3BaseAddress,
+  IN PHYSICAL_ADDRESS         BaseAddress,
+  IN UINTN                    NumPages
+  )
+{
+  //
+  // Memory encryption bit is not accessible in 32-bit mode
+  //
+  return RETURN_UNSUPPORTED;
+}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/MemEncryptSevLib.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/MemEncryptSevLib.c
index 4fea6a6be0ac..a2bf698bcde7 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/MemEncryptSevLib.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/MemEncryptSevLib.c
@@ -118,3 +118,36 @@ MemEncryptSevGetAddressRangeState (
            Length
            );
 }
+
+/**
+  This function clears memory encryption bit for the mmio region specified by
+  BaseAddress and NumPages.
+
+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use
+                                      current CR3)
+  @param[in]  BaseAddress             The physical address that is the start
+                                      address of a mmio region.
+  @param[in]  NumPages                The number of pages from start memory
+                                      region.
+
+  @retval RETURN_SUCCESS              The attributes were cleared for the
+                                      memory region.
+  @retval RETURN_INVALID_PARAMETER    Number of pages is zero.
+  @retval RETURN_UNSUPPORTED          Clearing the memory encryption attribute
+                                      is not supported
+**/
+RETURN_STATUS
+EFIAPI
+MemEncryptSevClearMmioPageEncMask (
+  IN PHYSICAL_ADDRESS         Cr3BaseAddress,
+  IN PHYSICAL_ADDRESS         BaseAddress,
+  IN UINTN                    NumPages
+  )
+{
+  return InternalMemEncryptSevClearMmioPageEncMask (
+           Cr3BaseAddress,
+           BaseAddress,
+           EFI_PAGES_TO_SIZE (NumPages)
+           );
+
+}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
index d3455e812bd1..a18d336a8789 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
@@ -891,3 +891,36 @@ InternalMemEncryptSevSetMemoryEncrypted (
            Flush
            );
 }
+
+/**
+  This function clears memory encryption bit for the MMIO region specified by
+  PhysicalAddress and Length.
+
+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use
+                                      current CR3)
+  @param[in]  PhysicalAddress         The physical address that is the start
+                                      address of a MMIO region.
+  @param[in]  Length                  The length of memory region
+
+  @retval RETURN_SUCCESS              The attributes were cleared for the
+                                      memory region.
+  @retval RETURN_INVALID_PARAMETER    Length is zero.
+  @retval RETURN_UNSUPPORTED          Clearing the memory encyrption attribute
+                                      is not supported
+**/
+RETURN_STATUS
+EFIAPI
+InternalMemEncryptSevClearMmioPageEncMask (
+  IN  PHYSICAL_ADDRESS        Cr3BaseAddress,
+  IN  PHYSICAL_ADDRESS        PhysicalAddress,
+  IN  UINTN                   Length
+  )
+{
+  return SetMemoryEncDec (
+           Cr3BaseAddress,
+           PhysicalAddress,
+           Length,
+           ClearCBit,
+           FALSE
+           );
+}
-- 
2.17.1