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x86/mm: Validate kernel_physical_mapping_init() PTE population
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The usage of __flush_tlb_all() in the kernel_physical_mapping_init()
path is not necessary. In general flushing the TLB is not required when
updating an entry from the !present state. However, to give confidence
in the future removal of TLB flushing in this path, use the new
set_pte_safe() family of helpers to assert that the !present assumption
is true in this path.

[ mingo: Minor readability edits. ]

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/154395944177.32119.8524957429632012270.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Dan Williams authored and Ingo Molnar committed Dec 5, 2018
1 parent 4369dea commit 0a9fe8c
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Showing 6 changed files with 43 additions and 12 deletions.
27 changes: 27 additions & 0 deletions arch/x86/include/asm/pgalloc.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,13 @@ static inline void pmd_populate_kernel(struct mm_struct *mm,
set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
}

static inline void pmd_populate_kernel_safe(struct mm_struct *mm,
pmd_t *pmd, pte_t *pte)
{
paravirt_alloc_pte(mm, __pa(pte) >> PAGE_SHIFT);
set_pmd_safe(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
}

static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
struct page *pte)
{
Expand Down Expand Up @@ -132,6 +139,12 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT);
set_pud(pud, __pud(_PAGE_TABLE | __pa(pmd)));
}

static inline void pud_populate_safe(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
{
paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT);
set_pud_safe(pud, __pud(_PAGE_TABLE | __pa(pmd)));
}
#endif /* CONFIG_X86_PAE */

#if CONFIG_PGTABLE_LEVELS > 3
Expand All @@ -141,6 +154,12 @@ static inline void p4d_populate(struct mm_struct *mm, p4d_t *p4d, pud_t *pud)
set_p4d(p4d, __p4d(_PAGE_TABLE | __pa(pud)));
}

static inline void p4d_populate_safe(struct mm_struct *mm, p4d_t *p4d, pud_t *pud)
{
paravirt_alloc_pud(mm, __pa(pud) >> PAGE_SHIFT);
set_p4d_safe(p4d, __p4d(_PAGE_TABLE | __pa(pud)));
}

static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
{
gfp_t gfp = GFP_KERNEL_ACCOUNT;
Expand Down Expand Up @@ -173,6 +192,14 @@ static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, p4d_t *p4d)
set_pgd(pgd, __pgd(_PAGE_TABLE | __pa(p4d)));
}

static inline void pgd_populate_safe(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_safe(pgd, __pgd(_PAGE_TABLE | __pa(p4d)));
}

static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr)
{
gfp_t gfp = GFP_KERNEL_ACCOUNT;
Expand Down
24 changes: 12 additions & 12 deletions arch/x86/mm/init_64.c
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Original file line number Diff line number Diff line change
Expand Up @@ -432,7 +432,7 @@ phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
E820_TYPE_RAM) &&
!e820__mapped_any(paddr & PAGE_MASK, paddr_next,
E820_TYPE_RESERVED_KERN))
set_pte(pte, __pte(0));
set_pte_safe(pte, __pte(0));
continue;
}

Expand All @@ -452,7 +452,7 @@ phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
pr_info(" pte=%p addr=%lx pte=%016lx\n", pte, paddr,
pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL).pte);
pages++;
set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
set_pte_safe(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
paddr_last = (paddr & PAGE_MASK) + PAGE_SIZE;
}

Expand Down Expand Up @@ -487,7 +487,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
E820_TYPE_RAM) &&
!e820__mapped_any(paddr & PMD_MASK, paddr_next,
E820_TYPE_RESERVED_KERN))
set_pmd(pmd, __pmd(0));
set_pmd_safe(pmd, __pmd(0));
continue;
}

Expand Down Expand Up @@ -524,7 +524,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
if (page_size_mask & (1<<PG_LEVEL_2M)) {
pages++;
spin_lock(&init_mm.page_table_lock);
set_pte((pte_t *)pmd,
set_pte_safe((pte_t *)pmd,
pfn_pte((paddr & PMD_MASK) >> PAGE_SHIFT,
__pgprot(pgprot_val(prot) | _PAGE_PSE)));
spin_unlock(&init_mm.page_table_lock);
Expand All @@ -536,7 +536,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
paddr_last = phys_pte_init(pte, paddr, paddr_end, new_prot);

spin_lock(&init_mm.page_table_lock);
pmd_populate_kernel(&init_mm, pmd, pte);
pmd_populate_kernel_safe(&init_mm, pmd, pte);
spin_unlock(&init_mm.page_table_lock);
}
update_page_count(PG_LEVEL_2M, pages);
Expand Down Expand Up @@ -573,7 +573,7 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
E820_TYPE_RAM) &&
!e820__mapped_any(paddr & PUD_MASK, paddr_next,
E820_TYPE_RESERVED_KERN))
set_pud(pud, __pud(0));
set_pud_safe(pud, __pud(0));
continue;
}

Expand Down Expand Up @@ -611,7 +611,7 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
if (page_size_mask & (1<<PG_LEVEL_1G)) {
pages++;
spin_lock(&init_mm.page_table_lock);
set_pte((pte_t *)pud,
set_pte_safe((pte_t *)pud,
pfn_pte((paddr & PUD_MASK) >> PAGE_SHIFT,
PAGE_KERNEL_LARGE));
spin_unlock(&init_mm.page_table_lock);
Expand All @@ -624,7 +624,7 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
page_size_mask, prot);

spin_lock(&init_mm.page_table_lock);
pud_populate(&init_mm, pud, pmd);
pud_populate_safe(&init_mm, pud, pmd);
spin_unlock(&init_mm.page_table_lock);
}
__flush_tlb_all();
Expand Down Expand Up @@ -659,7 +659,7 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end,
E820_TYPE_RAM) &&
!e820__mapped_any(paddr & P4D_MASK, paddr_next,
E820_TYPE_RESERVED_KERN))
set_p4d(p4d, __p4d(0));
set_p4d_safe(p4d, __p4d(0));
continue;
}

Expand All @@ -677,7 +677,7 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end,
page_size_mask);

spin_lock(&init_mm.page_table_lock);
p4d_populate(&init_mm, p4d, pud);
p4d_populate_safe(&init_mm, p4d, pud);
spin_unlock(&init_mm.page_table_lock);
}
__flush_tlb_all();
Expand Down Expand Up @@ -723,9 +723,9 @@ kernel_physical_mapping_init(unsigned long paddr_start,

spin_lock(&init_mm.page_table_lock);
if (pgtable_l5_enabled())
pgd_populate(&init_mm, pgd, p4d);
pgd_populate_safe(&init_mm, pgd, p4d);
else
p4d_populate(&init_mm, p4d_offset(pgd, vaddr), (pud_t *) p4d);
p4d_populate_safe(&init_mm, p4d_offset(pgd, vaddr), (pud_t *) p4d);
spin_unlock(&init_mm.page_table_lock);
pgd_changed = true;
}
Expand Down
1 change: 1 addition & 0 deletions include/asm-generic/5level-fixup.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#define p4d_clear(p4d) pgd_clear(p4d)
#define p4d_val(p4d) pgd_val(p4d)
#define p4d_populate(mm, p4d, pud) pgd_populate(mm, p4d, pud)
#define p4d_populate_safe(mm, p4d, pud) pgd_populate(mm, p4d, pud)
#define p4d_page(p4d) pgd_page(p4d)
#define p4d_page_vaddr(p4d) pgd_page_vaddr(p4d)

Expand Down
1 change: 1 addition & 0 deletions include/asm-generic/pgtable-nop4d-hack.h
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ static inline void pgd_clear(pgd_t *pgd) { }
#define pud_ERROR(pud) (pgd_ERROR((pud).pgd))

#define pgd_populate(mm, pgd, pud) do { } while (0)
#define pgd_populate_safe(mm, pgd, pud) do { } while (0)
/*
* (puds are folded into pgds so this doesn't get actually called,
* but the define is needed for a generic inline function.)
Expand Down
1 change: 1 addition & 0 deletions include/asm-generic/pgtable-nop4d.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@ static inline void pgd_clear(pgd_t *pgd) { }
#define p4d_ERROR(p4d) (pgd_ERROR((p4d).pgd))

#define pgd_populate(mm, pgd, p4d) do { } while (0)
#define pgd_populate_safe(mm, pgd, p4d) do { } while (0)
/*
* (p4ds are folded into pgds so this doesn't get actually called,
* but the define is needed for a generic inline function.)
Expand Down
1 change: 1 addition & 0 deletions include/asm-generic/pgtable-nopud.h
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ static inline void p4d_clear(p4d_t *p4d) { }
#define pud_ERROR(pud) (p4d_ERROR((pud).p4d))

#define p4d_populate(mm, p4d, pud) do { } while (0)
#define p4d_populate_safe(mm, p4d, pud) do { } while (0)
/*
* (puds are folded into p4ds so this doesn't get actually called,
* but the define is needed for a generic inline function.)
Expand Down

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