Commit a0a8d15a authored by Kiryl Shutsemau's avatar Kiryl Shutsemau Committed by Dave Hansen
Browse files

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'.

Reported-and-tested-by: default avatarChris Oo <cho@microsoft.com>

Fixes: 41394e33 ("x86/tdx: Extend the confidential computing API to support TDX guests")
Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: default avatarKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240424082035.4092071-1-kirill.shutemov%40linux.intel.com
parent b53c6bd5

arch/x86/include/asm/coco.h

+1 −0
Original line number Diff line number Diff line
@@ -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)

{

arch/x86/include/asm/pgtable_types.h

+2 −1
Original line number Diff line number Diff line
@@ -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)