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UefiCpuPkg/PiSmmCpuDxeSmm:Fix PF issue caused by smm page table code

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When setting new page table pool to RO, only disable/enable WP when
Cr0.WP has been set to 1 to fix potential PF caused by b822be1a20
(UefiCpuPkg/PiSmmCpuDxeSmm: Introduce page table pool mechanism).
With previous code, if someone want to modify the page table and
Cr0.WP has been cleared before modify page table, Cr0.WP may be set
to 1 again since new pool may be generated during this process
Then PF fault may happens.

Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
This commit is contained in:
Tan, Dun 2023-01-03 13:56:17 +08:00 committed by mergify[bot]
parent bbd30066e1
commit b670700ddf
1 changed files with 27 additions and 14 deletions
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19
UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
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@ -69,6 +69,8 @@ InitializePageTablePool (
{ {
VOID *Buffer; VOID *Buffer;
BOOLEAN CetEnabled; BOOLEAN CetEnabled;
BOOLEAN WpEnabled;
IA32_CR0 Cr0;
// //
// Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for
@ -106,16 +108,26 @@ InitializePageTablePool (
// //
if (mIsReadOnlyPageTable) { if (mIsReadOnlyPageTable) {
CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE; CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE;
Cr0.UintN = AsmReadCr0 ();
WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE;
if (WpEnabled) {
if (CetEnabled) { if (CetEnabled) {
// //
// CET must be disabled if WP is disabled. // CET must be disabled if WP is disabled. Disable CET before clearing CR0.WP.
// //
DisableCet (); DisableCet ();
} }
AsmWriteCr0 (AsmReadCr0 () & ~CR0_WP); Cr0.Bits.WP = 0;
AsmWriteCr0 (Cr0.UintN);
}
SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO); SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO);
AsmWriteCr0 (AsmReadCr0 () | CR0_WP); if (WpEnabled) {
Cr0.UintN = AsmReadCr0 ();
Cr0.Bits.WP = 1;
AsmWriteCr0 (Cr0.UintN);
if (CetEnabled) { if (CetEnabled) {
// //
// re-enable CET. // re-enable CET.
@ -123,6 +135,7 @@ InitializePageTablePool (
EnableCet (); EnableCet ();
} }
} }
}
return TRUE; return TRUE;
} }