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Subject[PATCHv7 14/19] x86/mm: Fold p4d page table layer at runtime
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This patch changes page table helpers to fold p4d at runtime.
The logic is the same as in <asm-generic/pgtable-nop4d.h>.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/include/asm/paravirt.h | 10 ++++++----
arch/x86/include/asm/pgalloc.h | 5 ++++-
arch/x86/include/asm/pgtable.h | 10 +++++++++-
3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 12deec722cf0..757fdac42a4a 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -569,14 +569,16 @@ static inline p4dval_t p4d_val(p4d_t p4d)

static inline void set_pgd(pgd_t *pgdp, pgd_t pgd)
{
- pgdval_t val = native_pgd_val(pgd);
-
- PVOP_VCALL2(pv_mmu_ops.set_pgd, pgdp, val);
+ if (pgtable_l5_enabled)
+ PVOP_VCALL2(pv_mmu_ops.set_pgd, pgdp, native_pgd_val(pgd));
+ else
+ set_p4d((p4d_t *)(pgdp), (p4d_t) { pgd.pgd });
}

static inline void pgd_clear(pgd_t *pgdp)
{
- set_pgd(pgdp, __pgd(0));
+ if (pgtable_l5_enabled)
+ set_pgd(pgdp, __pgd(0));
}

#endif /* CONFIG_PGTABLE_LEVELS == 5 */
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index b2d0cd8288aa..1ce12afcfb04 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -155,6 +155,8 @@ static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
#if CONFIG_PGTABLE_LEVELS > 4
static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, p4d_t *p4d)
{
+ if (!pgtable_l5_enabled)
+ return;
paravirt_alloc_p4d(mm, __pa(p4d) >> PAGE_SHIFT);
set_pgd(pgd, __pgd(_PAGE_TABLE | __pa(p4d)));
}
@@ -179,7 +181,8 @@ extern void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d);
static inline void __p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
unsigned long address)
{
- ___p4d_free_tlb(tlb, p4d);
+ if (pgtable_l5_enabled)
+ ___p4d_free_tlb(tlb, p4d);
}

#endif /* CONFIG_PGTABLE_LEVELS > 4 */
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index b714934512b3..51f37df28b7a 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -63,7 +63,7 @@ extern pmdval_t early_pmd_flags;

#ifndef __PAGETABLE_P4D_FOLDED
#define set_pgd(pgdp, pgd) native_set_pgd(pgdp, pgd)
-#define pgd_clear(pgd) native_pgd_clear(pgd)
+#define pgd_clear(pgd) (pgtable_l5_enabled ? native_pgd_clear(pgd) : 0)
#endif

#ifndef set_p4d
@@ -857,6 +857,8 @@ static inline unsigned long p4d_index(unsigned long address)
#if CONFIG_PGTABLE_LEVELS > 4
static inline int pgd_present(pgd_t pgd)
{
+ if (!pgtable_l5_enabled)
+ return 1;
return pgd_flags(pgd) & _PAGE_PRESENT;
}

@@ -874,16 +876,22 @@ static inline unsigned long pgd_page_vaddr(pgd_t pgd)
/* to find an entry in a page-table-directory. */
static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address)
{
+ if (!pgtable_l5_enabled)
+ return (p4d_t *)pgd;
return (p4d_t *)pgd_page_vaddr(*pgd) + p4d_index(address);
}

static inline int pgd_bad(pgd_t pgd)
{
+ if (!pgtable_l5_enabled)
+ return 0;
return (pgd_flags(pgd) & ~_PAGE_USER) != _KERNPG_TABLE;
}

static inline int pgd_none(pgd_t pgd)
{
+ if (!pgtable_l5_enabled)
+ return 0;
/*
* There is no need to do a workaround for the KNL stray
* A/D bit erratum here. PGDs only point to page tables
--
2.14.1
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