FAILED: patch "[PATCH] x86/tdx: Preserve shared bit on mprotect()" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x a0a8d15a798be4b8f20aca2ba91bf6b688c6a640
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024042908-modular-case-bbd4@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

a0a8d15a798b ("x86/tdx: Preserve shared bit on mprotect()") e45964771007 ("x86/coco: Define cc_vendor without CONFIG_ARCH_HAS_CC_PLATFORM")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a0a8d15a798be4b8f20aca2ba91bf6b688c6a640 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <[email protected]>
Date: Wed, 24 Apr 2024 11:20:35 +0300
Subject: [PATCH] x86/tdx: Preserve shared bit on mprotect()

The TDX guest platform takes one bit from the physical address to indicate if the page is shared (accessible by VMM). This bit is not part of the physical_mask and is not preserved during mprotect(). As a result, the 'shared' bit is lost during mprotect() on shared mappings.

_COMMON_PAGE_CHG_MASK specifies which PTE bits need to be preserved during modification. AMD includes 'sme_me_mask' in the define to preserve the 'encrypt' bit.

To cover both Intel and AMD cases, include 'cc_mask' in _COMMON_PAGE_CHG_MASK instead of 'sme_me_mask'.

index c086699b0d0c..aa6c8f8ca958 100644
@@ -25,6 +25,7 @@ u64 cc_mkdec(u64 val);
 void cc_random_init(void);
 #else
 #define cc_vendor (CC_VENDOR_NONE)
+static const u64 cc_mask = 0;
 
 static inline u64 cc_mkenc(u64 val)
 {

index 0b748ee16b3d..9abb8cc4cd47 100644
@@ -148,7 +148,7 @@
 #define _COMMON_PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |	\
 				 _PAGE_SPECIAL | _PAGE_ACCESSED |	\
 				 _PAGE_DIRTY_BITS | _PAGE_SOFT_DIRTY |	\
-				 _PAGE_DEVMAP | _PAGE_ENC | _PAGE_UFFD_WP)
+				 _PAGE_DEVMAP | _PAGE_CC | _PAGE_UFFD_WP)
 #define _PAGE_CHG_MASK	(_COMMON_PAGE_CHG_MASK | _PAGE_PAT)
 #define _HPAGE_CHG_MASK (_COMMON_PAGE_CHG_MASK | _PAGE_PSE | _PAGE_PAT_LARGE)
 

@@ -173,6 +173,7 @@ enum page_cache_mode {
 };
 #endif
 
+#define _PAGE_CC		(_AT(pteval_t, cc_mask))
 #define _PAGE_ENC		(_AT(pteval_t, sme_me_mask))
 
 #define _PAGE_CACHE_MASK	(_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)

The TDX guest platform takes one bit from the physical address to indicate if the page is shared (accessible by VMM). This bit is not part of the physical_mask and is not preserved during mprotect(). As a result, the 'shared' bit is lost during mprotect() on shared mappings.

_COMMON_PAGE_CHG_MASK specifies which PTE bits need to be preserved during modification. AMD includes 'sme_me_mask' in the define to preserve the 'encrypt' bit.

To cover both Intel and AMD cases, include 'cc_mask' in _COMMON_PAGE_CHG_MASK instead of 'sme_me_mask'.

---
 arch/x86/include/asm/coco.h          | 5 ++++-
 arch/x86/include/asm/pgtable_types.h | 3 ++-
 2 files changed, 6 insertions(+), 2 deletions(-)

index de03537a0182..c72b3553081c 100644
@@ -12,9 +12,10 @@ enum cc_vendor {
 };
 
 extern enum cc_vendor cc_vendor;
-extern u64 cc_mask;
 
 #ifdef CONFIG_ARCH_HAS_CC_PLATFORM
+extern u64 cc_mask;
+
 static inline void cc_set_mask(u64 mask)
 {
 	RIP_REL_REF(cc_mask) = mask;

@@ -24,6 +25,8 @@ u64 cc_mkenc(u64 val);
 u64 cc_mkdec(u64 val);
 void cc_random_init(void);
 #else
+static const u64 cc_mask = 0;
+
 static inline u64 cc_mkenc(u64 val)
 {
 	return val;

index 0b748ee16b3d..9abb8cc4cd47 100644
@@ -148,7 +148,7 @@
 #define _COMMON_PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |	\
 				 _PAGE_SPECIAL | _PAGE_ACCESSED |	\
 				 _PAGE_DIRTY_BITS | _PAGE_SOFT_DIRTY |	\
-				 _PAGE_DEVMAP | _PAGE_ENC | _PAGE_UFFD_WP)
+				 _PAGE_DEVMAP | _PAGE_CC | _PAGE_UFFD_WP)
 #define _PAGE_CHG_MASK	(_COMMON_PAGE_CHG_MASK | _PAGE_PAT)
 #define _HPAGE_CHG_MASK (_COMMON_PAGE_CHG_MASK | _PAGE_PSE | _PAGE_PAT_LARGE)
 

@@ -173,6 +173,7 @@ enum page_cache_mode {
 };
 #endif
 
+#define _PAGE_CC		(_AT(pteval_t, cc_mask))
 #define _PAGE_ENC		(_AT(pteval_t, sme_me_mask))
 
 #define _PAGE_CACHE_MASK	(_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)

2.43.0

Both backports now queued up, thanks.

greg k-h