mm/arm64: support large pfn mappings

Support huge pfnmaps by using bit 56 (PTE_SPECIAL) for "special" on
pmds/puds.  Provide the pmd/pud helpers to set/get special bit.

There's one more thing missing for arm64 which is the pxx_pgprot() for
pmd/pud.  Add them too, which is mostly the same as the pte version by
dropping the pfn field.  These helpers are essential to be used in the new
follow_pfnmap*() API to report valid pgprot_t results.

Note that arm64 doesn't yet support huge PUD yet, but it's still
straightforward to provide the pud helpers that we need altogether.  Only
PMD helpers will make an immediate benefit until arm64 will support huge
PUDs first in general (e.g.  in THPs).

Link: https://lkml.kernel.org/r/20240826204353.2228736-19-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gavin Shan <gshan@redhat.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6494848019a05972f139fc16d7225228e67da52c..6607ed8fdbb4e2381d28f66274fbbec623512752 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -99,6 +99,7 @@ config ARM64
        select ARCH_SUPPORTS_NUMA_BALANCING
        select ARCH_SUPPORTS_PAGE_TABLE_CHECK
        select ARCH_SUPPORTS_PER_VMA_LOCK
+       select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
        select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
        select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
        select ARCH_WANT_DEFAULT_BPF_JIT

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index b78cc4a6758b85715159099603397f0378ddb503..2faecc033a199d23863bde8317e8fd2100f3653c 100644 (file)
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -578,6 +578,14 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd)
        return pte_pmd(set_pte_bit(pmd_pte(pmd), __pgprot(PTE_DEVMAP)));
 }
 
+#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
+#define pmd_special(pte)       (!!((pmd_val(pte) & PTE_SPECIAL)))
+static inline pmd_t pmd_mkspecial(pmd_t pmd)
+{
+       return set_pmd_bit(pmd, __pgprot(PTE_SPECIAL));
+}
+#endif
+
 #define __pmd_to_phys(pmd)     __pte_to_phys(pmd_pte(pmd))
 #define __phys_to_pmd_val(phys)        __phys_to_pte_val(phys)
 #define pmd_pfn(pmd)           ((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT)
@@ -595,6 +603,27 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd)
 #define pud_pfn(pud)           ((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT)
 #define pfn_pud(pfn,prot)      __pud(__phys_to_pud_val((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
 
+#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
+#define pud_special(pte)       pte_special(pud_pte(pud))
+#define pud_mkspecial(pte)     pte_pud(pte_mkspecial(pud_pte(pud)))
+#endif
+
+#define pmd_pgprot pmd_pgprot
+static inline pgprot_t pmd_pgprot(pmd_t pmd)
+{
+       unsigned long pfn = pmd_pfn(pmd);
+
+       return __pgprot(pmd_val(pfn_pmd(pfn, __pgprot(0))) ^ pmd_val(pmd));
+}
+
+#define pud_pgprot pud_pgprot
+static inline pgprot_t pud_pgprot(pud_t pud)
+{
+       unsigned long pfn = pud_pfn(pud);
+
+       return __pgprot(pud_val(pfn_pud(pfn, __pgprot(0))) ^ pud_val(pud));
+}
+
 static inline void __set_pte_at(struct mm_struct *mm,
                                unsigned long __always_unused addr,
                                pte_t *ptep, pte_t pte, unsigned int nr)