Reviewed-by: Ray Ni <ray...@intel.com>
> -----Original Message-----
> From: Tan, Dun <dun....@intel.com>
> Sent: Tuesday, May 16, 2023 5:59 PM
> To: devel@edk2.groups.io
> Cc: Dong, Eric <eric.d...@intel.com>; Ni, Ray <ray...@intel.com>; Kumar, Rahul
> R <rahul.r.ku...@intel.com>; Gerd Hoffmann <kra...@redhat.com>
> Subject: [Patch V4 07/15] UefiCpuPkg/PiSmmCpuDxeSmm: Add 2 function to
> disable/enable CR0.WP
>
> Add two functions to disable/enable CR0.WP. These two unctions
> will also be used in later commits. This commit doesn't change any
> functionality.
>
> Signed-off-by: Dun Tan <dun....@intel.com>
> Cc: Eric Dong <eric.d...@intel.com>
> Cc: Ray Ni <ray...@intel.com>
> Cc: Rahul Kumar <rahul1.ku...@intel.com>
> Cc: Gerd Hoffmann <kra...@redhat.com>
> ---
> UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 24
> ++++++++++++++++++++++++
> UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 115
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> +-------------------------------------------------
> 2 files changed, 90 insertions(+), 49 deletions(-)
>
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> index ba341cadc6..e0c4ca76dc 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> @@ -1565,4 +1565,28 @@ SmmWaitForApArrival (
> VOID
> );
>
> +/**
> + Disable Write Protect on pages marked as read-only if Cr0.Bits.WP is 1.
> +
> + @param[out] WpEnabled If Cr0.WP is enabled.
> + @param[out] CetEnabled If CET is enabled.
> +**/
> +VOID
> +DisableReadOnlyPageWriteProtect (
> + OUT BOOLEAN *WpEnabled,
> + OUT BOOLEAN *CetEnabled
> + );
> +
> +/**
> + Enable Write Protect on pages marked as read-only.
> +
> + @param[out] WpEnabled If Cr0.WP should be enabled.
> + @param[out] CetEnabled If CET should be enabled.
> +**/
> +VOID
> +EnableReadOnlyPageWriteProtect (
> + BOOLEAN WpEnabled,
> + BOOLEAN CetEnabled
> + );
> +
> #endif
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
> index 2faee8f859..4b512edf68 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
> @@ -40,6 +40,64 @@ PAGE_TABLE_POOL *mPageTablePool = NULL;
> //
> BOOLEAN mIsReadOnlyPageTable = FALSE;
>
> +/**
> + Disable Write Protect on pages marked as read-only if Cr0.Bits.WP is 1.
> +
> + @param[out] WpEnabled If Cr0.WP is enabled.
> + @param[out] CetEnabled If CET is enabled.
> +**/
> +VOID
> +DisableReadOnlyPageWriteProtect (
> + OUT BOOLEAN *WpEnabled,
> + OUT BOOLEAN *CetEnabled
> + )
> +{
> + IA32_CR0 Cr0;
> +
> + *CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE;
> + Cr0.UintN = AsmReadCr0 ();
> + *WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE;
> + if (*WpEnabled) {
> + if (*CetEnabled) {
> + //
> + // CET must be disabled if WP is disabled. Disable CET before clearing
> CR0.WP.
> + //
> + DisableCet ();
> + }
> +
> + Cr0.Bits.WP = 0;
> + AsmWriteCr0 (Cr0.UintN);
> + }
> +}
> +
> +/**
> + Enable Write Protect on pages marked as read-only.
> +
> + @param[out] WpEnabled If Cr0.WP should be enabled.
> + @param[out] CetEnabled If CET should be enabled.
> +**/
> +VOID
> +EnableReadOnlyPageWriteProtect (
> + BOOLEAN WpEnabled,
> + BOOLEAN CetEnabled
> + )
> +{
> + IA32_CR0 Cr0;
> +
> + if (WpEnabled) {
> + Cr0.UintN = AsmReadCr0 ();
> + Cr0.Bits.WP = 1;
> + AsmWriteCr0 (Cr0.UintN);
> +
> + if (CetEnabled) {
> + //
> + // re-enable CET.
> + //
> + EnableCet ();
> + }
> + }
> +}
> +
> /**
> Initialize a buffer pool for page table use only.
>
> @@ -62,10 +120,9 @@ InitializePageTablePool (
> IN UINTN PoolPages
> )
> {
> - VOID *Buffer;
> - BOOLEAN CetEnabled;
> - BOOLEAN WpEnabled;
> - IA32_CR0 Cr0;
> + VOID *Buffer;
> + BOOLEAN WpEnabled;
> + BOOLEAN CetEnabled;
>
> //
> // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page
> for
> @@ -102,34 +159,9 @@ InitializePageTablePool (
> // If page table memory has been marked as RO, mark the new pool pages as
> read-only.
> //
> if (mIsReadOnlyPageTable) {
> - CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE;
> - Cr0.UintN = AsmReadCr0 ();
> - WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE;
> - if (WpEnabled) {
> - if (CetEnabled) {
> - //
> - // CET must be disabled if WP is disabled. Disable CET before
> clearing
> CR0.WP.
> - //
> - DisableCet ();
> - }
> -
> - Cr0.Bits.WP = 0;
> - AsmWriteCr0 (Cr0.UintN);
> - }
> -
> + DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
> SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer,
> EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO);
> - if (WpEnabled) {
> - Cr0.UintN = AsmReadCr0 ();
> - Cr0.Bits.WP = 1;
> - AsmWriteCr0 (Cr0.UintN);
> -
> - if (CetEnabled) {
> - //
> - // re-enable CET.
> - //
> - EnableCet ();
> - }
> - }
> + EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
> }
>
> return TRUE;
> @@ -1782,6 +1814,7 @@ SetPageTableAttributes (
> VOID
> )
> {
> + BOOLEAN WpEnabled;
> BOOLEAN CetEnabled;
>
> if (!IfReadOnlyPageTableNeeded ()) {
> @@ -1794,15 +1827,7 @@ SetPageTableAttributes (
> // Disable write protection, because we need mark page table to be write
> protected.
> // We need *write* page table memory, to mark itself to be *read only*.
> //
> - CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE;
> - if (CetEnabled) {
> - //
> - // CET must be disabled if WP is disabled.
> - //
> - DisableCet ();
> - }
> -
> - AsmWriteCr0 (AsmReadCr0 () & ~CR0_WP);
> + DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
>
> // Set memory used by page table as Read Only.
> DEBUG ((DEBUG_INFO, "Start...\n"));
> @@ -1811,20 +1836,12 @@ SetPageTableAttributes (
> //
> // Enable write protection, after page table attribute updated.
> //
> - AsmWriteCr0 (AsmReadCr0 () | CR0_WP);
> + EnableReadOnlyPageWriteProtect (TRUE, CetEnabled);
> mIsReadOnlyPageTable = TRUE;
>
> //
> // Flush TLB after mark all page table pool as read only.
> //
> FlushTlbForAll ();
> -
> - if (CetEnabled) {
> - //
> - // re-enable CET.
> - //
> - EnableCet ();
> - }
> -
> return;
> }
> --
> 2.31.1.windows.1
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