mm, x86: add support for PUD-sized transparent hugepages

The current transparent hugepage code only supports PMDs.  This patch
adds support for transparent use of PUDs with DAX.  It does not include
support for anonymous pages.  x86 support code also added.

Most of this patch simply parallels the work that was done for huge
PMDs.  The only major difference is how the new ->pud_entry method in
mm_walk works.  The ->pmd_entry method replaces the ->pte_entry method,
whereas the ->pud_entry method works along with either ->pmd_entry or
->pte_entry.  The pagewalk code takes care of locking the PUD before
calling ->pud_walk, so handlers do not need to worry whether the PUD is
stable.

[dave.jiang@intel.com: fix SMP x86 32bit build for native_pud_clear()]
  Link: http://lkml.kernel.org/r/148719066814.31111.3239231168815337012.stgit@djiang5-desk3.ch.intel.com
[dave.jiang@intel.com: native_pud_clear missing on i386 build]
  Link: http://lkml.kernel.org/r/148640375195.69754.3315433724330910314.stgit@djiang5-desk3.ch.intel.com
Link: http://lkml.kernel.org/r/148545059381.17912.8602162635537598445.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Alexander Kapshuk <alexander.kapshuk@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

9 files changed, 248 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 874c1238dffd..33007aa74111 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -109,6 +109,7 @@ config X86
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
+	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
 	select HAVE_ARCH_VMAP_STACK		if X86_64
 	select HAVE_ARCH_WITHIN_STACK_FRAMES
 	select HAVE_CC_STACKPROTECTOR
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index f75fbfe550f2..0489884fdc44 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -475,6 +475,17 @@ static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 			    native_pmd_val(pmd));
 }
 
+static inline void set_pud_at(struct mm_struct *mm, unsigned long addr,
+			      pud_t *pudp, pud_t pud)
+{
+	if (sizeof(pudval_t) > sizeof(long))
+		/* 5 arg words */
+		pv_mmu_ops.set_pud_at(mm, addr, pudp, pud);
+	else
+		PVOP_VCALL4(pv_mmu_ops.set_pud_at, mm, addr, pudp,
+			    native_pud_val(pud));
+}
+
 static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
 {
 	pmdval_t val = native_pmd_val(pmd);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index bb2de45a60f2..b060f962d581 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -249,6 +249,8 @@ struct pv_mmu_ops {
 	void (*set_pmd)(pmd_t *pmdp, pmd_t pmdval);
 	void (*set_pmd_at)(struct mm_struct *mm, unsigned long addr,
 			   pmd_t *pmdp, pmd_t pmdval);
+	void (*set_pud_at)(struct mm_struct *mm, unsigned long addr,
+			   pud_t *pudp, pud_t pudval);
 	void (*pte_update)(struct mm_struct *mm, unsigned long addr,
 			   pte_t *ptep);
 
diff --git a/arch/x86/include/asm/pgtable-2level.h b/arch/x86/include/asm/pgtable-2level.h
index fd74a11959de..a8b96e708c2b 100644
--- a/arch/x86/include/asm/pgtable-2level.h
+++ b/arch/x86/include/asm/pgtable-2level.h
@@ -21,6 +21,10 @@ static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
 	*pmdp = pmd;
 }
 
+static inline void native_set_pud(pud_t *pudp, pud_t pud)
+{
+}
+
 static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
 {
 	native_set_pte(ptep, pte);
@@ -31,6 +35,10 @@ static inline void native_pmd_clear(pmd_t *pmdp)
 	native_set_pmd(pmdp, __pmd(0));
 }
 
+static inline void native_pud_clear(pud_t *pudp)
+{
+}
+
 static inline void native_pte_clear(struct mm_struct *mm,
 				    unsigned long addr, pte_t *xp)
 {
@@ -55,6 +63,15 @@ static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
 #define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
 #endif
 
+#ifdef CONFIG_SMP
+static inline pud_t native_pudp_get_and_clear(pud_t *xp)
+{
+	return __pud(xchg((pudval_t *)xp, 0));
+}
+#else
+#define native_pudp_get_and_clear(xp) native_local_pudp_get_and_clear(xp)
+#endif
+
 /* Bit manipulation helper on pte/pgoff entry */
 static inline unsigned long pte_bitop(unsigned long value, unsigned int rightshift,
 				      unsigned long mask, unsigned int leftshift)
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index cdaa58c9b39e..8f50fb3f04e1 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -121,6 +121,12 @@ static inline void native_pmd_clear(pmd_t *pmd)
 	*(tmp + 1) = 0;
 }
 
+#ifndef CONFIG_SMP
+static inline void native_pud_clear(pud_t *pudp)
+{
+}
+#endif
+
 static inline void pud_clear(pud_t *pudp)
 {
 	set_pud(pudp, __pud(0));
@@ -176,6 +182,30 @@ static inline pmd_t native_pmdp_get_and_clear(pmd_t *pmdp)
 #define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
 #endif
 
+#ifdef CONFIG_SMP
+union split_pud {
+	struct {
+		u32 pud_low;
+		u32 pud_high;
+	};
+	pud_t pud;
+};
+
+static inline pud_t native_pudp_get_and_clear(pud_t *pudp)
+{
+	union split_pud res, *orig = (union split_pud *)pudp;
+
+	/* xchg acts as a barrier before setting of the high bits */
+	res.pud_low = xchg(&orig->pud_low, 0);
+	res.pud_high = orig->pud_high;
+	orig->pud_high = 0;
+
+	return res.pud;
+}
+#else
+#define native_pudp_get_and_clear(xp) native_local_pudp_get_and_clear(xp)
+#endif
+
 /* Encode and de-code a swap entry */
 #define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > 5)
 #define __swp_type(x)			(((x).val) & 0x1f)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 437feb436efa..1cfb36b8c024 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -46,6 +46,7 @@ extern struct mm_struct *pgd_page_get_mm(struct page *page);
 #define set_pte(ptep, pte)		native_set_pte(ptep, pte)
 #define set_pte_at(mm, addr, ptep, pte)	native_set_pte_at(mm, addr, ptep, pte)
 #define set_pmd_at(mm, addr, pmdp, pmd)	native_set_pmd_at(mm, addr, pmdp, pmd)
+#define set_pud_at(mm, addr, pudp, pud)	native_set_pud_at(mm, addr, pudp, pud)
 
 #define set_pte_atomic(ptep, pte)					\
 	native_set_pte_atomic(ptep, pte)
@@ -128,6 +129,16 @@ static inline int pmd_young(pmd_t pmd)
 	return pmd_flags(pmd) & _PAGE_ACCESSED;
 }
 
+static inline int pud_dirty(pud_t pud)
+{
+	return pud_flags(pud) & _PAGE_DIRTY;
+}
+
+static inline int pud_young(pud_t pud)
+{
+	return pud_flags(pud) & _PAGE_ACCESSED;
+}
+
 static inline int pte_write(pte_t pte)
 {
 	return pte_flags(pte) & _PAGE_RW;
@@ -181,6 +192,13 @@ static inline int pmd_trans_huge(pmd_t pmd)
 	return (pmd_val(pmd) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
 }
 
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static inline int pud_trans_huge(pud_t pud)
+{
+	return (pud_val(pud) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
+}
+#endif
+
 #define has_transparent_hugepage has_transparent_hugepage
 static inline int has_transparent_hugepage(void)
 {
@@ -192,6 +210,18 @@ static inline int pmd_devmap(pmd_t pmd)
 {
 	return !!(pmd_val(pmd) & _PAGE_DEVMAP);
 }
+
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static inline int pud_devmap(pud_t pud)
+{
+	return !!(pud_val(pud) & _PAGE_DEVMAP);
+}
+#else
+static inline int pud_devmap(pud_t pud)
+{
+	return 0;
+}
+#endif
 #endif
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
@@ -333,6 +363,65 @@ static inline pmd_t pmd_mknotpresent(pmd_t pmd)
 	return pmd_clear_flags(pmd, _PAGE_PRESENT | _PAGE_PROTNONE);
 }
 
+static inline pud_t pud_set_flags(pud_t pud, pudval_t set)
+{
+	pudval_t v = native_pud_val(pud);
+
+	return __pud(v | set);
+}
+
+static inline pud_t pud_clear_flags(pud_t pud, pudval_t clear)
+{
+	pudval_t v = native_pud_val(pud);
+
+	return __pud(v & ~clear);
+}
+
+static inline pud_t pud_mkold(pud_t pud)
+{
+	return pud_clear_flags(pud, _PAGE_ACCESSED);
+}
+
+static inline pud_t pud_mkclean(pud_t pud)
+{
+	return pud_clear_flags(pud, _PAGE_DIRTY);
+}
+
+static inline pud_t pud_wrprotect(pud_t pud)
+{
+	return pud_clear_flags(pud, _PAGE_RW);
+}
+
+static inline pud_t pud_mkdirty(pud_t pud)
+{
+	return pud_set_flags(pud, _PAGE_DIRTY | _PAGE_SOFT_DIRTY);
+}
+
+static inline pud_t pud_mkdevmap(pud_t pud)
+{
+	return pud_set_flags(pud, _PAGE_DEVMAP);
+}
+
+static inline pud_t pud_mkhuge(pud_t pud)
+{
+	return pud_set_flags(pud, _PAGE_PSE);
+}
+
+static inline pud_t pud_mkyoung(pud_t pud)
+{
+	return pud_set_flags(pud, _PAGE_ACCESSED);
+}
+
+static inline pud_t pud_mkwrite(pud_t pud)
+{
+	return pud_set_flags(pud, _PAGE_RW);
+}
+
+static inline pud_t pud_mknotpresent(pud_t pud)
+{
+	return pud_clear_flags(pud, _PAGE_PRESENT | _PAGE_PROTNONE);
+}
+
 #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
 static inline int pte_soft_dirty(pte_t pte)
 {
@@ -344,6 +433,11 @@ static inline int pmd_soft_dirty(pmd_t pmd)
 	return pmd_flags(pmd) & _PAGE_SOFT_DIRTY;
 }
 
+static inline int pud_soft_dirty(pud_t pud)
+{
+	return pud_flags(pud) & _PAGE_SOFT_DIRTY;
+}
+
 static inline pte_t pte_mksoft_dirty(pte_t pte)
 {
 	return pte_set_flags(pte, _PAGE_SOFT_DIRTY);
@@ -354,6 +448,11 @@ static inline pmd_t pmd_mksoft_dirty(pmd_t pmd)
 	return pmd_set_flags(pmd, _PAGE_SOFT_DIRTY);
 }
 
+static inline pud_t pud_mksoft_dirty(pud_t pud)
+{
+	return pud_set_flags(pud, _PAGE_SOFT_DIRTY);
+}
+
 static inline pte_t pte_clear_soft_dirty(pte_t pte)
 {
 	return pte_clear_flags(pte, _PAGE_SOFT_DIRTY);
@@ -364,6 +463,11 @@ static inline pmd_t pmd_clear_soft_dirty(pmd_t pmd)
 	return pmd_clear_flags(pmd, _PAGE_SOFT_DIRTY);
 }
 
+static inline pud_t pud_clear_soft_dirty(pud_t pud)
+{
+	return pud_clear_flags(pud, _PAGE_SOFT_DIRTY);
+}
+
 #endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */
 
 /*
@@ -392,6 +496,12 @@ static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
 		     massage_pgprot(pgprot));
 }
 
+static inline pud_t pfn_pud(unsigned long page_nr, pgprot_t pgprot)
+{
+	return __pud(((phys_addr_t)page_nr << PAGE_SHIFT) |
+		     massage_pgprot(pgprot));
+}
+
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
 	pteval_t val = pte_val(pte);
@@ -771,6 +881,14 @@ static inline pmd_t native_local_pmdp_get_and_clear(pmd_t *pmdp)
 	return res;
 }
 
+static inline pud_t native_local_pudp_get_and_clear(pud_t *pudp)
+{
+	pud_t res = *pudp;
+
+	native_pud_clear(pudp);
+	return res;
+}
+
 static inline void native_set_pte_at(struct mm_struct *mm, unsigned long addr,
 				     pte_t *ptep , pte_t pte)
 {
@@ -783,6 +901,12 @@ static inline void native_set_pmd_at(struct mm_struct *mm, unsigned long addr,
 	native_set_pmd(pmdp, pmd);
 }
 
+static inline void native_set_pud_at(struct mm_struct *mm, unsigned long addr,
+				     pud_t *pudp, pud_t pud)
+{
+	native_set_pud(pudp, pud);
+}
+
 #ifndef CONFIG_PARAVIRT
 /*
  * Rules for using pte_update - it must be called after any PTE update which
@@ -861,10 +985,15 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm,
 extern int pmdp_set_access_flags(struct vm_area_struct *vma,
 				 unsigned long address, pmd_t *pmdp,
 				 pmd_t entry, int dirty);
+extern int pudp_set_access_flags(struct vm_area_struct *vma,
+				 unsigned long address, pud_t *pudp,
+				 pud_t entry, int dirty);
 
 #define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
 extern int pmdp_test_and_clear_young(struct vm_area_struct *vma,
 				     unsigned long addr, pmd_t *pmdp);
+extern int pudp_test_and_clear_young(struct vm_area_struct *vma,
+				     unsigned long addr, pud_t *pudp);
 
 #define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
 extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
@@ -884,6 +1013,13 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm, unsigned long
 	return native_pmdp_get_and_clear(pmdp);
 }
 
+#define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR
+static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm,
+					unsigned long addr, pud_t *pudp)
+{
+	return native_pudp_get_and_clear(pudp);
+}
+
 #define __HAVE_ARCH_PMDP_SET_WRPROTECT
 static inline void pmdp_set_wrprotect(struct mm_struct *mm,
 				      unsigned long addr, pmd_t *pmdp)
@@ -932,6 +1068,10 @@ static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
 		unsigned long addr, pmd_t *pmd)
 {
 }
+static inline void update_mmu_cache_pud(struct vm_area_struct *vma,
+		unsigned long addr, pud_t *pud)
+{
+}
 
 #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
 static inline pte_t pte_swp_mksoft_dirty(pte_t pte)
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 62b775926045..73c7ccc38912 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -106,6 +106,21 @@ static inline void native_pud_clear(pud_t *pud)
 	native_set_pud(pud, native_make_pud(0));
 }
 
+static inline pud_t native_pudp_get_and_clear(pud_t *xp)
+{
+#ifdef CONFIG_SMP
+	return native_make_pud(xchg(&xp->pud, 0));
+#else
+	/* native_local_pudp_get_and_clear,
+	 * but duplicated because of cyclic dependency
+	 */
+	pud_t ret = *xp;
+
+	native_pud_clear(xp);
+	return ret;
+#endif
+}
+
 static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd)
 {
 	*pgdp = pgd;
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index a1bfba0f7234..4797e87b0fb6 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -425,6 +425,7 @@ struct pv_mmu_ops pv_mmu_ops __ro_after_init = {
 	.pmd_clear = native_pmd_clear,
 #endif
 	.set_pud = native_set_pud,
+	.set_pud_at = native_set_pud_at,
 
 	.pmd_val = PTE_IDENT,
 	.make_pmd = PTE_IDENT,
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 3feec5af4e67..6cbdff26bb96 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -445,6 +445,26 @@ int pmdp_set_access_flags(struct vm_area_struct *vma,
 
 	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 = !pud_same(*pudp, entry);
+
+	VM_BUG_ON(address & ~HPAGE_PUD_MASK);
+
+	if (changed && dirty) {
+		*pudp = entry;
+		/*
+		 * We had a write-protection fault here and changed the pud
+		 * to to more permissive. No need to flush the TLB for that,
+		 * #PF is architecturally guaranteed to do that and in the
+		 * worst-case we'll generate a spurious fault.
+		 */
+	}
+
+	return changed;
+}
 #endif
 
 int ptep_test_and_clear_young(struct vm_area_struct *vma,
@@ -474,6 +494,17 @@ int pmdp_test_and_clear_young(struct vm_area_struct *vma,
 
 	return ret;
 }
+int pudp_test_and_clear_young(struct vm_area_struct *vma,
+			      unsigned long addr, pud_t *pudp)
+{
+	int ret = 0;
+
+	if (pud_young(*pudp))
+		ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
+					 (unsigned long *)pudp);
+
+	return ret;
+}
 #endif
 
 int ptep_clear_flush_young(struct vm_area_struct *vma,