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Date: Tue, 18 Jul 2017 16:24:06 +0200
From: Juergen Gross <jgross@...e.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>
Cc: Andi Kleen <ak@...ux.intel.com>,
Dave Hansen <dave.hansen@...el.com>,
Andy Lutomirski <luto@...capital.net>,
Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 08/10] x86/mm: Replace compile-time checks for 5-level
with runtime-time
On 18/07/17 16:15, Kirill A. Shutemov wrote:
> This patch converts the of CONFIG_X86_5LEVEL check to runtime checks for
> p4d folding.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
> arch/x86/mm/fault.c | 2 +-
> arch/x86/mm/ident_map.c | 2 +-
> arch/x86/mm/init_64.c | 30 ++++++++++++++++++------------
> arch/x86/mm/kasan_init_64.c | 8 ++++----
> arch/x86/mm/kaslr.c | 6 +++---
> arch/x86/platform/efi/efi_64.c | 2 +-
> arch/x86/power/hibernate_64.c | 6 +++---
> arch/x86/xen/mmu_pv.c | 2 +-
> 8 files changed, 32 insertions(+), 26 deletions(-)
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 2a1fa10c6a98..d3d8f10f0c10 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -459,7 +459,7 @@ static noinline int vmalloc_fault(unsigned long address)
> if (pgd_none(*pgd)) {
> set_pgd(pgd, *pgd_ref);
> arch_flush_lazy_mmu_mode();
> - } else if (CONFIG_PGTABLE_LEVELS > 4) {
> + } else if (!p4d_folded) {
> /*
> * With folded p4d, pgd_none() is always false, so the pgd may
> * point to an empty page table entry and pgd_page_vaddr()
> diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
> index adab1595f4bd..d2df33a2cbfb 100644
> --- a/arch/x86/mm/ident_map.c
> +++ b/arch/x86/mm/ident_map.c
> @@ -115,7 +115,7 @@ int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
> result = ident_p4d_init(info, p4d, addr, next);
> if (result)
> return result;
> - if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
> + if (!p4d_folded) {
> set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
> } else {
> /*
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 649b8df485ad..6b97f6c1bf77 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -88,12 +88,7 @@ static int __init nonx32_setup(char *str)
> }
> __setup("noexec32=", nonx32_setup);
>
> -/*
> - * When memory was added make sure all the processes MM have
> - * suitable PGD entries in the local PGD level page.
> - */
> -#ifdef CONFIG_X86_5LEVEL
> -void sync_global_pgds(unsigned long start, unsigned long end)
> +static void sync_global_pgds_57(unsigned long start, unsigned long end)
> {
> unsigned long addr;
>
> @@ -129,8 +124,8 @@ void sync_global_pgds(unsigned long start, unsigned long end)
> spin_unlock(&pgd_lock);
> }
> }
> -#else
> -void sync_global_pgds(unsigned long start, unsigned long end)
> +
> +static void sync_global_pgds_48(unsigned long start, unsigned long end)
> {
> unsigned long addr;
>
> @@ -173,7 +168,18 @@ void sync_global_pgds(unsigned long start, unsigned long end)
> spin_unlock(&pgd_lock);
> }
> }
> -#endif
> +
> +/*
> + * When memory was added make sure all the processes MM have
> + * suitable PGD entries in the local PGD level page.
> + */
> +void sync_global_pgds(unsigned long start, unsigned long end)
> +{
> + if (!p4d_folded)
> + sync_global_pgds_57(start, end);
> + else
> + sync_global_pgds_48(start, end);
> +}
>
> /*
> * NOTE: This function is marked __ref because it calls __init function
> @@ -632,7 +638,7 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end,
> unsigned long vaddr = (unsigned long)__va(paddr);
> int i = p4d_index(vaddr);
>
> - if (!IS_ENABLED(CONFIG_X86_5LEVEL))
> + if (p4d_folded)
> return phys_pud_init((pud_t *) p4d_page, paddr, paddr_end, page_size_mask);
>
> for (; i < PTRS_PER_P4D; i++, paddr = paddr_next) {
> @@ -712,7 +718,7 @@ kernel_physical_mapping_init(unsigned long paddr_start,
> page_size_mask);
>
> spin_lock(&init_mm.page_table_lock);
> - if (IS_ENABLED(CONFIG_X86_5LEVEL))
> + if (!p4d_folded)
> pgd_populate(&init_mm, pgd, p4d);
> else
> p4d_populate(&init_mm, p4d_offset(pgd, vaddr), (pud_t *) p4d);
> @@ -1078,7 +1084,7 @@ remove_p4d_table(p4d_t *p4d_start, unsigned long addr, unsigned long end,
> * 5-level case we should free them. This code will have to change
> * to adapt for boot-time switching between 4 and 5 level page tables.
> */
> - if (CONFIG_PGTABLE_LEVELS == 5)
> + if (!p4d_folded)
> free_pud_table(pud_base, p4d);
> }
>
> diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
> index cff8d85fef7b..ee12861e0609 100644
> --- a/arch/x86/mm/kasan_init_64.c
> +++ b/arch/x86/mm/kasan_init_64.c
> @@ -40,7 +40,7 @@ static void __init clear_pgds(unsigned long start,
> * With folded p4d, pgd_clear() is nop, use p4d_clear()
> * instead.
> */
> - if (CONFIG_PGTABLE_LEVELS < 5)
> + if (p4d_folded)
> p4d_clear(p4d_offset(pgd, start));
> else
> pgd_clear(pgd);
> @@ -55,7 +55,7 @@ static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
> {
> unsigned long p4d;
>
> - if (!IS_ENABLED(CONFIG_X86_5LEVEL))
> + if (p4d_folded)
> return (p4d_t *)pgd;
>
> p4d = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK;
> @@ -135,7 +135,7 @@ void __init kasan_early_init(void)
> for (i = 0; i < PTRS_PER_PUD; i++)
> kasan_zero_pud[i] = __pud(pud_val);
>
> - for (i = 0; IS_ENABLED(CONFIG_X86_5LEVEL) && i < PTRS_PER_P4D; i++)
> + for (i = 0; !p4d_folded && i < PTRS_PER_P4D; i++)
> kasan_zero_p4d[i] = __p4d(p4d_val);
>
> kasan_map_early_shadow(early_top_pgt);
> @@ -152,7 +152,7 @@ void __init kasan_init(void)
>
> memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
>
> - if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
> + if (!p4d_folded) {
> void *ptr;
>
> ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
> diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
> index 2f6ba5c72905..b70f86a2ce6a 100644
> --- a/arch/x86/mm/kaslr.c
> +++ b/arch/x86/mm/kaslr.c
> @@ -139,7 +139,7 @@ void __init kernel_randomize_memory(void)
> */
> entropy = remain_entropy / (ARRAY_SIZE(kaslr_regions) - i);
> prandom_bytes_state(&rand_state, &rand, sizeof(rand));
> - if (IS_ENABLED(CONFIG_X86_5LEVEL))
> + if (!p4d_folded)
> entropy = (rand % (entropy + 1)) & P4D_MASK;
> else
> entropy = (rand % (entropy + 1)) & PUD_MASK;
> @@ -151,7 +151,7 @@ void __init kernel_randomize_memory(void)
> * randomization alignment.
> */
> vaddr += get_padding(&kaslr_regions[i]);
> - if (IS_ENABLED(CONFIG_X86_5LEVEL))
> + if (!p4d_folded)
> vaddr = round_up(vaddr + 1, P4D_SIZE);
> else
> vaddr = round_up(vaddr + 1, PUD_SIZE);
> @@ -227,7 +227,7 @@ void __meminit init_trampoline(void)
> return;
> }
>
> - if (IS_ENABLED(CONFIG_X86_5LEVEL))
> + if (!p4d_folded)
> init_trampoline_p4d();
> else
> init_trampoline_pud();
> diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
> index 3cda4fd8ed2b..91d9076ee216 100644
> --- a/arch/x86/platform/efi/efi_64.c
> +++ b/arch/x86/platform/efi/efi_64.c
> @@ -219,7 +219,7 @@ int __init efi_alloc_page_tables(void)
>
> pud = pud_alloc(&init_mm, p4d, EFI_VA_END);
> if (!pud) {
> - if (CONFIG_PGTABLE_LEVELS > 4)
> + if (!p4d_folded)
> free_page((unsigned long) pgd_page_vaddr(*pgd));
> free_page((unsigned long)efi_pgd);
> return -ENOMEM;
> diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
> index f2598d81cd55..9b9bc2ef4321 100644
> --- a/arch/x86/power/hibernate_64.c
> +++ b/arch/x86/power/hibernate_64.c
> @@ -50,7 +50,7 @@ static int set_up_temporary_text_mapping(pgd_t *pgd)
> {
> pmd_t *pmd;
> pud_t *pud;
> - p4d_t *p4d;
> + p4d_t *p4d = NULL;
>
> /*
> * The new mapping only has to cover the page containing the image
> @@ -66,7 +66,7 @@ static int set_up_temporary_text_mapping(pgd_t *pgd)
> * tables used by the image kernel.
> */
>
> - if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
> + if (!p4d_folded) {
> p4d = (p4d_t *)get_safe_page(GFP_ATOMIC);
> if (!p4d)
> return -ENOMEM;
> @@ -84,7 +84,7 @@ static int set_up_temporary_text_mapping(pgd_t *pgd)
> __pmd((jump_address_phys & PMD_MASK) | __PAGE_KERNEL_LARGE_EXEC));
> set_pud(pud + pud_index(restore_jump_address),
> __pud(__pa(pmd) | _KERNPG_TABLE));
> - if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
> + if (p4d) {
> set_p4d(p4d + p4d_index(restore_jump_address), __p4d(__pa(pud) | _KERNPG_TABLE));
> set_pgd(pgd + pgd_index(restore_jump_address), __pgd(__pa(p4d) | _KERNPG_TABLE));
> } else {
> diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
> index cab28cf2cffb..b0530184c637 100644
> --- a/arch/x86/xen/mmu_pv.c
> +++ b/arch/x86/xen/mmu_pv.c
> @@ -1209,7 +1209,7 @@ static void __init xen_cleanmfnmap(unsigned long vaddr)
> continue;
> xen_cleanmfnmap_p4d(p4d + i, unpin);
> }
> - if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
> + if (!p4d_folded) {
> set_pgd(pgd, __pgd(0));
> xen_cleanmfnmap_free_pgtbl(p4d, unpin);
> }
Xen PV guests will never run with 5-level-paging enabled. So I guess you
can drop the complete if (IS_ENABLED(CONFIG_X86_5LEVEL)) {} block.
Juergen
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