#include <Library/CpuLib.h>
#include <Library/MemEncryptSevLib.h>
#include <Register/Amd/Cpuid.h>
#include <Register/Cpuid.h>
#include "VirtualMemory.h"
#include "SnpPageStateChange.h"

Enumerations
enum	MAP_RANGE_MODE { SetCBit , ClearCBit }

Functions
UINT64 EFIAPI	InternalGetMemEncryptionAddressMask (VOID)

STATIC BOOLEAN	InitializePageTablePool (IN UINTN PoolPages)

STATIC VOID *EFIAPI	AllocatePageTableMemory (IN UINTN Pages)

STATIC VOID	Split2MPageTo4K (IN PHYSICAL_ADDRESS PhysicalAddress, IN OUT UINT64 *PageEntry2M, IN PHYSICAL_ADDRESS StackBase, IN UINTN StackSize)

STATIC VOID	SetPageTablePoolReadOnly (IN UINTN PageTableBase, IN EFI_PHYSICAL_ADDRESS Address, IN BOOLEAN Level4Paging)

STATIC VOID	EnablePageTableProtection (IN UINTN PageTableBase, IN BOOLEAN Level4Paging)

STATIC VOID	Split1GPageTo2M (IN PHYSICAL_ADDRESS PhysicalAddress, IN OUT UINT64 *PageEntry1G, IN PHYSICAL_ADDRESS StackBase, IN UINTN StackSize)

STATIC VOID	SetOrClearCBit (IN OUT UINT64 *PageTablePointer, IN MAP_RANGE_MODE Mode)

STATIC BOOLEAN	IsReadOnlyPageWriteProtected (VOID)

STATIC VOID	DisableReadOnlyPageWriteProtect (VOID)

STATIC VOID	EnableReadOnlyPageWriteProtect (VOID)

RETURN_STATUS EFIAPI	InternalMemEncryptSevCreateIdentityMap1G (IN PHYSICAL_ADDRESS Cr3BaseAddress, IN PHYSICAL_ADDRESS PhysicalAddress, IN UINTN Length)

STATIC RETURN_STATUS EFIAPI	SetMemoryEncDec (IN PHYSICAL_ADDRESS Cr3BaseAddress, IN PHYSICAL_ADDRESS PhysicalAddress, IN UINTN Length, IN MAP_RANGE_MODE Mode, IN BOOLEAN CacheFlush, IN BOOLEAN Mmio)

RETURN_STATUS EFIAPI	InternalMemEncryptSevSetMemoryDecrypted (IN PHYSICAL_ADDRESS Cr3BaseAddress, IN PHYSICAL_ADDRESS PhysicalAddress, IN UINTN Length)

RETURN_STATUS EFIAPI	InternalMemEncryptSevSetMemoryEncrypted (IN PHYSICAL_ADDRESS Cr3BaseAddress, IN PHYSICAL_ADDRESS PhysicalAddress, IN UINTN Length)

RETURN_STATUS EFIAPI	InternalMemEncryptSevClearMmioPageEncMask (IN PHYSICAL_ADDRESS Cr3BaseAddress, IN PHYSICAL_ADDRESS PhysicalAddress, IN UINTN Length)

Variables
STATIC BOOLEAN	mAddressEncMaskChecked = FALSE

STATIC UINT64	mAddressEncMask

STATIC PAGE_TABLE_POOL *	mPageTablePool = NULL

STATIC VOID *	mPscBuffer = NULL

Detailed Description

Virtual Memory Management Services to set or clear the memory encryption bit

SPDX-License-Identifier: BSD-2-Clause-Patent

Code is derived from MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c

Definition in file PeiDxeVirtualMemory.c.

Enumeration Type Documentation

◆ MAP_RANGE_MODE

enum MAP_RANGE_MODE

Definition at line 28 of file PeiDxeVirtualMemory.c.

Function Documentation

◆ AllocatePageTableMemory()

STATIC VOID *EFIAPI AllocatePageTableMemory ( IN UINTN Pages )

This API provides a way to allocate memory for page table.

This API can be called more than once to allocate memory for page tables.

Allocates the number of 4KB pages and returns a pointer to the allocated buffer. The buffer returned is aligned on a 4KB boundary.

If Pages is 0, then NULL is returned. If there is not enough memory remaining to satisfy the request, then NULL is returned.

Parameters

Pages The number of 4 KB pages to allocate.

Returns: A pointer to the allocated buffer or NULL if allocation fails.

Definition at line 139 of file PeiDxeVirtualMemory.c.

◆ DisableReadOnlyPageWriteProtect()

STATIC VOID DisableReadOnlyPageWriteProtect ( VOID )

Disable Write Protect on pages marked as read-only.

Definition at line 534 of file PeiDxeVirtualMemory.c.

◆ EnablePageTableProtection()

STATIC VOID EnablePageTableProtection	(	IN UINTN	PageTableBase,
		IN BOOLEAN	Level4Paging
	)

Prevent the memory pages used for page table from been overwritten.

Parameters

[in]	PageTableBase	Base address of page table (CR3).
[in]	Level4Paging	Level 4 paging flag.

Definition at line 382 of file PeiDxeVirtualMemory.c.

◆ EnableReadOnlyPageWriteProtect()

STATIC VOID EnableReadOnlyPageWriteProtect ( VOID )

Enable Write Protect on pages marked as read-only.

Definition at line 546 of file PeiDxeVirtualMemory.c.

◆ InitializePageTablePool()

STATIC BOOLEAN InitializePageTablePool ( IN UINTN PoolPages )

Initialize a buffer pool for page table use only.

To reduce the potential split operation on page table, the pages reserved for page table should be allocated in the times of PAGE_TABLE_POOL_UNIT_PAGES and at the boundary of PAGE_TABLE_POOL_ALIGNMENT. So the page pool is always initialized with number of pages greater than or equal to the given PoolPages.

Once the pages in the pool are used up, this method should be called again to reserve at least another PAGE_TABLE_POOL_UNIT_PAGES. Usually this won't happen often in practice.

Parameters

[in] PoolPages The least page number of the pool to be created.

Return values

TRUE	The pool is initialized successfully.
FALSE	The memory is out of resource.

Definition at line 79 of file PeiDxeVirtualMemory.c.

◆ InternalGetMemEncryptionAddressMask()

UINT64 EFIAPI InternalGetMemEncryptionAddressMask ( VOID )

Return the pagetable memory encryption mask.

Returns: The pagetable memory encryption mask.

Definition at line 41 of file PeiDxeVirtualMemory.c.

◆ InternalMemEncryptSevClearMmioPageEncMask()

RETURN_STATUS EFIAPI InternalMemEncryptSevClearMmioPageEncMask	(	IN PHYSICAL_ADDRESS	Cr3BaseAddress,
		IN PHYSICAL_ADDRESS	PhysicalAddress,
		IN UINTN	Length
	)

This function clears memory encryption bit for the MMIO region specified by PhysicalAddress and Length.

Parameters

[in]	Cr3BaseAddress	Cr3 Base Address (if zero then use current CR3)
[in]	PhysicalAddress	The physical address that is the start address of a MMIO region.
[in]	Length	The length of memory region

Return values

RETURN_SUCCESS	The attributes were cleared for the memory region.
RETURN_INVALID_PARAMETER	Length is zero.
RETURN_UNSUPPORTED	Clearing the memory encyrption attribute is not supported

Definition at line 1104 of file PeiDxeVirtualMemory.c.

◆ InternalMemEncryptSevCreateIdentityMap1G()

RETURN_STATUS EFIAPI InternalMemEncryptSevCreateIdentityMap1G	(	IN PHYSICAL_ADDRESS	Cr3BaseAddress,
		IN PHYSICAL_ADDRESS	PhysicalAddress,
		IN UINTN	Length
	)

Create 1GB identity mapping for the specified virtual address range.

The function is preliminary used by the SEV-SNP page state change APIs to build the page table required before issuing the PVALIDATE instruction. The function must be removed after the EDK2 core is enhanced to do the lazy validation.

Parameters

[in]	Cr3BaseAddress	Cr3 Base Address (if zero then use current CR3)
[in]	VirtualAddress	Virtual address
[in]	Length	Length of virtual address range

Return values

RETURN_INVALID_PARAMETER Number of pages is zero.

Definition at line 555 of file PeiDxeVirtualMemory.c.

◆ InternalMemEncryptSevSetMemoryDecrypted()

RETURN_STATUS EFIAPI InternalMemEncryptSevSetMemoryDecrypted	(	IN PHYSICAL_ADDRESS	Cr3BaseAddress,
		IN PHYSICAL_ADDRESS	PhysicalAddress,
		IN UINTN	Length
	)

This function clears memory encryption bit for the memory region specified by PhysicalAddress and Length from the current page table context.

Parameters

[in]	Cr3BaseAddress	Cr3 Base Address (if zero then use current CR3)
[in]	PhysicalAddress	The physical address that is the start address of a memory region.
[in]	Length	The length of memory region

Return values

RETURN_SUCCESS	The attributes were cleared for the memory region.
RETURN_INVALID_PARAMETER	Number of pages is zero.
RETURN_UNSUPPORTED	Clearing the memory encyrption attribute is not supported

Definition at line 1036 of file PeiDxeVirtualMemory.c.

◆ InternalMemEncryptSevSetMemoryEncrypted()

RETURN_STATUS EFIAPI InternalMemEncryptSevSetMemoryEncrypted	(	IN PHYSICAL_ADDRESS	Cr3BaseAddress,
		IN PHYSICAL_ADDRESS	PhysicalAddress,
		IN UINTN	Length
	)

This function sets memory encryption bit for the memory region specified by PhysicalAddress and Length from the current page table context.

Parameters

[in]	Cr3BaseAddress	Cr3 Base Address (if zero then use current CR3)
[in]	PhysicalAddress	The physical address that is the start address of a memory region.
[in]	Length	The length of memory region

Return values

RETURN_SUCCESS	The attributes were set for the memory region.
RETURN_INVALID_PARAMETER	Number of pages is zero.
RETURN_UNSUPPORTED	Setting the memory encyrption attribute is not supported

Definition at line 1070 of file PeiDxeVirtualMemory.c.

◆ IsReadOnlyPageWriteProtected()

STATIC BOOLEAN IsReadOnlyPageWriteProtected ( VOID )

Check the WP status in CR0 register. This bit is used to lock or unlock write access to pages marked as read-only.

Return values

TRUE	Write protection is enabled.
FALSE	Write protection is disabled.

Definition at line 522 of file PeiDxeVirtualMemory.c.

◆ SetMemoryEncDec()

STATIC RETURN_STATUS EFIAPI SetMemoryEncDec	(	IN PHYSICAL_ADDRESS	Cr3BaseAddress,
		IN PHYSICAL_ADDRESS	PhysicalAddress,
		IN UINTN	Length,
		IN MAP_RANGE_MODE	Mode,
		IN BOOLEAN	CacheFlush,
		IN BOOLEAN	Mmio
	)

This function either sets or clears memory encryption bit for the memory region specified by PhysicalAddress and Length from the current page table context.

The function iterates through the PhysicalAddress one page at a time, and set or clears the memory encryption mask in the page table. If it encounters that a given physical address range is part of large page then it attempts to change the attribute at one go (based on size), otherwise it splits the large pages into smaller (e.g 2M page into 4K pages) and then try to set or clear the encryption bit on the smallest page size.

Parameters

[in]	Cr3BaseAddress	Cr3 Base Address (if zero then use current CR3)
[in]	PhysicalAddress	The physical address that is the start address of a memory region.
[in]	Length	The length of memory region
[in]	Mode	Set or Clear mode
[in]	CacheFlush	Flush the caches before applying the encryption mask
[in]	Mmio	The physical address specified is Mmio

Return values

RETURN_SUCCESS	The attributes were cleared for the memory region.
RETURN_INVALID_PARAMETER	Number of pages is zero.
RETURN_UNSUPPORTED	Setting the memory encyrption attribute is not supported

Definition at line 711 of file PeiDxeVirtualMemory.c.

◆ SetOrClearCBit()

STATIC VOID SetOrClearCBit	(	IN OUT UINT64 *	PageTablePointer,
		IN MAP_RANGE_MODE	Mode
	)

Set or Clear the memory encryption bit

Parameters

[in,out]	PageTablePointer	Page table entry pointer (PTE).
[in]	Mode	Set or Clear encryption bit

Definition at line 497 of file PeiDxeVirtualMemory.c.

◆ SetPageTablePoolReadOnly()

STATIC VOID SetPageTablePoolReadOnly	(	IN UINTN	PageTableBase,
		IN EFI_PHYSICAL_ADDRESS	Address,
		IN BOOLEAN	Level4Paging
	)

Set one page of page table pool memory to be read-only.

Parameters

[in]	PageTableBase	Base address of page table (CR3).
[in]	Address	Start address of a page to be set as read-only.
[in]	Level4Paging	Level 4 paging flag.

Definition at line 257 of file PeiDxeVirtualMemory.c.

◆ Split1GPageTo2M()

STATIC VOID Split1GPageTo2M	(	IN PHYSICAL_ADDRESS	PhysicalAddress,
		IN OUT UINT64 *	PageEntry1G,
		IN PHYSICAL_ADDRESS	StackBase,
		IN UINTN	StackSize
	)

Split 1G page to 2M.

Parameters

[in]	PhysicalAddress	Start physical address the 1G page covered.
[in,out]	PageEntry1G	Pointer to 1G page entry.
[in]	StackBase	Stack base address.
[in]	StackSize	Stack size.

Definition at line 433 of file PeiDxeVirtualMemory.c.

◆ Split2MPageTo4K()

STATIC VOID Split2MPageTo4K	(	IN PHYSICAL_ADDRESS	PhysicalAddress,
		IN OUT UINT64 *	PageEntry2M,
		IN PHYSICAL_ADDRESS	StackBase,
		IN UINTN	StackSize
	)

Split 2M page to 4K.

Parameters

[in]	PhysicalAddress	Start physical address the 2M page covered.
[in,out]	PageEntry2M	Pointer to 2M page entry.
[in]	StackBase	Stack base address.
[in]	StackSize	Stack size.

Definition at line 189 of file PeiDxeVirtualMemory.c.

Variable Documentation

◆ mAddressEncMask

STATIC UINT64 mAddressEncMask

Definition at line 23 of file PeiDxeVirtualMemory.c.

◆ mAddressEncMaskChecked

STATIC BOOLEAN mAddressEncMaskChecked = FALSE

Definition at line 22 of file PeiDxeVirtualMemory.c.

◆ mPageTablePool

STATIC PAGE_TABLE_POOL* mPageTablePool = NULL

Definition at line 24 of file PeiDxeVirtualMemory.c.

◆ mPscBuffer

STATIC VOID* mPscBuffer = NULL

Definition at line 26 of file PeiDxeVirtualMemory.c.

Enumerations

Functions

Variables

Detailed Description

Enumeration Type Documentation

◆ MAP_RANGE_MODE

Function Documentation

◆ AllocatePageTableMemory()

◆ DisableReadOnlyPageWriteProtect()

◆ EnablePageTableProtection()

◆ EnableReadOnlyPageWriteProtect()

◆ InitializePageTablePool()

◆ InternalGetMemEncryptionAddressMask()

◆ InternalMemEncryptSevClearMmioPageEncMask()

◆ InternalMemEncryptSevCreateIdentityMap1G()

◆ InternalMemEncryptSevSetMemoryDecrypted()

◆ InternalMemEncryptSevSetMemoryEncrypted()

◆ IsReadOnlyPageWriteProtected()

◆ SetMemoryEncDec()

◆ SetOrClearCBit()

◆ SetPageTablePoolReadOnly()

◆ Split1GPageTo2M()

◆ Split2MPageTo4K()

Variable Documentation

◆ mAddressEncMask

◆ mAddressEncMaskChecked

◆ mPageTablePool

◆ mPscBuffer