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Shutemov" To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "Rafael J. Wysocki" , Peter Zijlstra , Adrian Hunter , Kuppuswamy Sathyanarayanan , Elena Reshetova , Jun Nakajima , Rick Edgecombe , Tom Lendacky , "Kalra, Ashish" , Sean Christopherson , "Huang, Kai" , Ard Biesheuvel , Baoquan He , "H. Peter Anvin" , "Kirill A. Shutemov" , "K. Y. Srinivasan" , Haiyang Zhang , kexec@lists.infradead.org, linux-hyperv@vger.kernel.org, linux-acpi@vger.kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, Dave Hansen , Tao Liu Subject: [PATCHv11 08/19] x86/mm: Return correct level from lookup_address() if pte is none Date: Tue, 28 May 2024 12:55:11 +0300 Message-ID: <20240528095522.509667-9-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240528095522.509667-1-kirill.shutemov@linux.intel.com> References: <20240528095522.509667-1-kirill.shutemov@linux.intel.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Currently, lookup_address() returns two things: 1. A "pte_t" (which might be a p[g4um]d_t) 2. The 'level' of the page tables where the "pte_t" was found (returned via a pointer) If no pte_t is found, 'level' is essentially garbage. Always fill out the level. For NULL "pte_t"s, fill in the level where the p*d_none() entry was found mirroring the "found" behavior. Always filling out the level allows using lookup_address() to precisely skip over holes when walking kernel page tables. Add one more entry into enum pg_level to indicate the size of the VA covered by one PGD entry in 5-level paging mode. Update comments for lookup_address() and lookup_address_in_pgd() to reflect changes in the interface. Signed-off-by: Kirill A. Shutemov Reviewed-by: Rick Edgecombe Reviewed-by: Baoquan He Reviewed-by: Dave Hansen Tested-by: Tao Liu --- arch/x86/include/asm/pgtable_types.h | 1 + arch/x86/mm/pat/set_memory.c | 21 ++++++++++----------- 2 files changed, 11 insertions(+), 11 deletions(-) diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index b78644962626..2f321137736c 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -549,6 +549,7 @@ enum pg_level { PG_LEVEL_2M, PG_LEVEL_1G, PG_LEVEL_512G, + PG_LEVEL_256T, PG_LEVEL_NUM }; diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 498812f067cd..a7a7a6c6a3fb 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -662,8 +662,9 @@ static inline pgprot_t verify_rwx(pgprot_t old, pgprot_t new, unsigned long star /* * Lookup the page table entry for a virtual address in a specific pgd. - * Return a pointer to the entry, the level of the mapping, and the effective - * NX and RW bits of all page table levels. + * Return a pointer to the entry (or NULL if the entry does not exist), + * the level of the entry, and the effective NX and RW bits of all + * page table levels. */ pte_t *lookup_address_in_pgd_attr(pgd_t *pgd, unsigned long address, unsigned int *level, bool *nx, bool *rw) @@ -672,13 +673,14 @@ pte_t *lookup_address_in_pgd_attr(pgd_t *pgd, unsigned long address, pud_t *pud; pmd_t *pmd; - *level = PG_LEVEL_NONE; + *level = PG_LEVEL_256T; *nx = false; *rw = true; if (pgd_none(*pgd)) return NULL; + *level = PG_LEVEL_512G; *nx |= pgd_flags(*pgd) & _PAGE_NX; *rw &= pgd_flags(*pgd) & _PAGE_RW; @@ -686,10 +688,10 @@ pte_t *lookup_address_in_pgd_attr(pgd_t *pgd, unsigned long address, if (p4d_none(*p4d)) return NULL; - *level = PG_LEVEL_512G; if (p4d_leaf(*p4d) || !p4d_present(*p4d)) return (pte_t *)p4d; + *level = PG_LEVEL_1G; *nx |= p4d_flags(*p4d) & _PAGE_NX; *rw &= p4d_flags(*p4d) & _PAGE_RW; @@ -697,10 +699,10 @@ pte_t *lookup_address_in_pgd_attr(pgd_t *pgd, unsigned long address, if (pud_none(*pud)) return NULL; - *level = PG_LEVEL_1G; if (pud_leaf(*pud) || !pud_present(*pud)) return (pte_t *)pud; + *level = PG_LEVEL_2M; *nx |= pud_flags(*pud) & _PAGE_NX; *rw &= pud_flags(*pud) & _PAGE_RW; @@ -708,15 +710,13 @@ pte_t *lookup_address_in_pgd_attr(pgd_t *pgd, unsigned long address, if (pmd_none(*pmd)) return NULL; - *level = PG_LEVEL_2M; if (pmd_leaf(*pmd) || !pmd_present(*pmd)) return (pte_t *)pmd; + *level = PG_LEVEL_4K; *nx |= pmd_flags(*pmd) & _PAGE_NX; *rw &= pmd_flags(*pmd) & _PAGE_RW; - *level = PG_LEVEL_4K; - return pte_offset_kernel(pmd, address); } @@ -736,9 +736,8 @@ pte_t *lookup_address_in_pgd(pgd_t *pgd, unsigned long address, * Lookup the page table entry for a virtual address. Return a pointer * to the entry and the level of the mapping. * - * Note: We return pud and pmd either when the entry is marked large - * or when the present bit is not set. Otherwise we would return a - * pointer to a nonexisting mapping. + * Note: the function returns p4d, pud or pmd either when the entry is marked + * large or when the present bit is not set. Otherwise it returns NULL. */ pte_t *lookup_address(unsigned long address, unsigned int *level) { -- 2.43.0