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Shutemov" , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@intel.com Cc: hpa@zytor.com, seanjc@google.com, elena.reshetova@intel.com, rick.p.edgecombe@intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, Tom Lendacky , Chris Oo , Dexuan Cui References: <20240412191247.369841-1-kirill.shutemov@linux.intel.com> Content-Language: en-US From: Kuppuswamy Sathyanarayanan In-Reply-To: <20240412191247.369841-1-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/12/24 12:12 PM, Kirill A. Shutemov wrote: > 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 support TDX guests") > Cc: Tom Lendacky > Cc: Chris Oo > Cc: Dexuan Cui > --- Looks good to me. Reviewed-by: Kuppuswamy Sathyanarayanan > arch/x86/include/asm/pgtable_types.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h > index 3f648ffdfbe5..7dd2fdfacff3 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_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) -- Sathyanarayanan Kuppuswamy Linux Kernel Developer