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Shutemov" To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@intel.com Cc: sathyanarayanan.kuppuswamy@linux.intel.com, hpa@zytor.com, seanjc@google.com, elena.reshetova@intel.com, rick.p.edgecombe@intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Chris Oo , Tom Lendacky , Dexuan Cui Subject: [PATCHv2] x86/tdx: Preserve shared bit on mprotect() Date: Fri, 19 Apr 2024 23:13:53 +0300 Message-ID: <20240419201353.3937135-1-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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'. Signed-off-by: Kirill A. Shutemov Fixes: 41394e33f3a0 ("x86/tdx: Extend the confidential computing API to sup= port TDX guests") Reported-and-tested-by: Chris Oo Reviewed-by: Rick Edgecombe Reviewed-by: Kuppuswamy Sathyanarayanan Cc: Tom Lendacky Cc: Dexuan Cui Reviewed-by: Tom Lendacky --- v2: - Fix build for !CONFIG_ARCH_HAS_CC_PLATFORM --- arch/x86/include/asm/coco.h | 1 + arch/x86/include/asm/pgtable_types.h | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/coco.h b/arch/x86/include/asm/coco.h index c086699b0d0c..ac8cd4447d48 100644 --- a/arch/x86/include/asm/coco.h +++ b/arch/x86/include/asm/coco.h @@ -25,6 +25,7 @@ u64 cc_mkdec(u64 val); void cc_random_init(void); #else #define cc_vendor (CC_VENDOR_NONE) +#define cc_mask 0 =20 static inline u64 cc_mkenc(u64 val) { diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pg= table_types.h index 8857d811fb5d..2f321137736c 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -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_LAR= GE) =20 @@ -173,6 +173,7 @@ enum page_cache_mode { }; #endif =20 +#define _PAGE_CC (_AT(pteval_t, cc_mask)) #define _PAGE_ENC (_AT(pteval_t, sme_me_mask)) =20 #define _PAGE_CACHE_MASK (_PAGE_PWT | _PAGE_PCD | _PAGE_PAT) --=20 2.43.0