powerpc/book3s64/mm: enable transparent pud hugepage

This is enabled only with radix translation and 1G hugepage size.  This
will be used with devdax device memory with a namespace alignment of 1G.

Anon transparent hugepage is not supported even though we do have helpers
checking pud_trans_huge().  We should never find that return true.  The
only expected pte bit combination is _PAGE_PTE | _PAGE_DEVMAP.

Some of the helpers are never expected to get called on hash translation
and hence is marked to call BUG() in such a case.

Link: https://lkml.kernel.org/r/20230724190759.483013-10-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 78 insertions, 0 deletions

diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 85c84e89e3ea..75b938268b04 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -64,11 +64,39 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
 	return changed;
 }
 
+int pudp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
+			  pud_t *pudp, pud_t entry, int dirty)
+{
+	int changed;
+#ifdef CONFIG_DEBUG_VM
+	WARN_ON(!pud_devmap(*pudp));
+	assert_spin_locked(pud_lockptr(vma->vm_mm, pudp));
+#endif
+	changed = !pud_same(*(pudp), entry);
+	if (changed) {
+		/*
+		 * We can use MMU_PAGE_1G here, because only radix
+		 * path look at the psize.
+		 */
+		__ptep_set_access_flags(vma, pudp_ptep(pudp),
+					pud_pte(entry), address, MMU_PAGE_1G);
+	}
+	return changed;
+}
+
+
 int pmdp_test_and_clear_young(struct vm_area_struct *vma,
 			      unsigned long address, pmd_t *pmdp)
 {
 	return __pmdp_test_and_clear_young(vma->vm_mm, address, pmdp);
 }
+
+int pudp_test_and_clear_young(struct vm_area_struct *vma,
+			      unsigned long address, pud_t *pudp)
+{
+	return __pudp_test_and_clear_young(vma->vm_mm, address, pudp);
+}
+
 /*
  * set a new huge pmd. We should not be called for updating
  * an existing pmd entry. That should go via pmd_hugepage_update.
@@ -90,6 +118,23 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 	return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
 }
 
+void set_pud_at(struct mm_struct *mm, unsigned long addr,
+		pud_t *pudp, pud_t pud)
+{
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * Make sure hardware valid bit is not set. We don't do
+	 * tlb flush for this update.
+	 */
+
+	WARN_ON(pte_hw_valid(pud_pte(*pudp)));
+	assert_spin_locked(pud_lockptr(mm, pudp));
+	WARN_ON(!(pud_large(pud)));
+#endif
+	trace_hugepage_set_pud(addr, pud_val(pud));
+	return set_pte_at(mm, addr, pudp_ptep(pudp), pud_pte(pud));
+}
+
 static void do_serialize(void *arg)
 {
 	/* We've taken the IPI, so try to trim the mask while here */
@@ -147,11 +192,35 @@ pmd_t pmdp_huge_get_and_clear_full(struct vm_area_struct *vma,
 	return pmd;
 }
 
+pud_t pudp_huge_get_and_clear_full(struct vm_area_struct *vma,
+				   unsigned long addr, pud_t *pudp, int full)
+{
+	pud_t pud;
+
+	VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
+	VM_BUG_ON((pud_present(*pudp) && !pud_devmap(*pudp)) ||
+		  !pud_present(*pudp));
+	pud = pudp_huge_get_and_clear(vma->vm_mm, addr, pudp);
+	/*
+	 * if it not a fullmm flush, then we can possibly end up converting
+	 * this PMD pte entry to a regular level 0 PTE by a parallel page fault.
+	 * Make sure we flush the tlb in this case.
+	 */
+	if (!full)
+		flush_pud_tlb_range(vma, addr, addr + HPAGE_PUD_SIZE);
+	return pud;
+}
+
 static pmd_t pmd_set_protbits(pmd_t pmd, pgprot_t pgprot)
 {
 	return __pmd(pmd_val(pmd) | pgprot_val(pgprot));
 }
 
+static pud_t pud_set_protbits(pud_t pud, pgprot_t pgprot)
+{
+	return __pud(pud_val(pud) | pgprot_val(pgprot));
+}
+
 /*
  * At some point we should be able to get rid of
  * pmd_mkhuge() and mk_huge_pmd() when we update all the
@@ -166,6 +235,15 @@ pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot)
 	return __pmd_mkhuge(pmd_set_protbits(__pmd(pmdv), pgprot));
 }
 
+pud_t pfn_pud(unsigned long pfn, pgprot_t pgprot)
+{
+	unsigned long pudv;
+
+	pudv = (pfn << PAGE_SHIFT) & PTE_RPN_MASK;
+
+	return __pud_mkhuge(pud_set_protbits(__pud(pudv), pgprot));
+}
+
 pmd_t mk_pmd(struct page *page, pgprot_t pgprot)
 {
 	return pfn_pmd(page_to_pfn(page), pgprot);