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Date: Wed, 17 Oct 2018 13:51:53 +0200
From: Christophe LEROY <christophe.leroy@....fr>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>,
aneesh.kumar@...ux.vnet.ibm.com
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 21/22] powerpc/nohash32: allow setting GUARDED
attribute in the PMD directly
Le 25/09/2018 à 18:51, Christophe Leroy a écrit :
> On the 8xx, the GUARDED attribute of the pages is managed in the
> L1 entry, therefore to avoid having to copy it into L1 entry
> at each TLB miss, we have to set it in the PMD
>
> In order to allow this, this patch splits the VM alloc space in two
> parts, one for VM alloc and non Guarded IO, and one for Guarded IO.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
I'm not too happy with this part, I think I'll drop it for now and
rework it in a future serie to something more generic using mm slices.
Christophe
> ---
> arch/powerpc/include/asm/book3s/32/pgalloc.h | 2 +-
> arch/powerpc/include/asm/book3s/32/pgtable.h | 2 ++
> arch/powerpc/include/asm/nohash/32/pgalloc.h | 19 ++++++++--
> arch/powerpc/include/asm/nohash/32/pgtable.h | 19 ++++++++--
> arch/powerpc/mm/dump_linuxpagetables.c | 21 +++++++++--
> arch/powerpc/mm/mem.c | 7 ++++
> arch/powerpc/mm/pgtable_32.c | 52 +++++++++++++++++++++++++---
> arch/powerpc/platforms/Kconfig.cputype | 2 ++
> 8 files changed, 112 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/32/pgalloc.h b/arch/powerpc/include/asm/book3s/32/pgalloc.h
> index 711a8b84e3ee..9097cfd4ce43 100644
> --- a/arch/powerpc/include/asm/book3s/32/pgalloc.h
> +++ b/arch/powerpc/include/asm/book3s/32/pgalloc.h
> @@ -139,7 +139,7 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t table,
> pgtable_free_tlb(tlb, page_address(table), 0);
> }
>
> -static inline pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
> +static inline pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va, bool is_g)
> {
> if (!pmd_present(*pmdp)) {
> pte_t *ptep = __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
> diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
> index 7a8a590f6b4c..28001d5eaa89 100644
> --- a/arch/powerpc/include/asm/book3s/32/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
> @@ -156,6 +156,8 @@ static inline bool pte_user(pte_t pte)
> #define IOREMAP_TOP KVIRT_TOP
> #endif
>
> +#define IOREMAP_BASE VMALLOC_START
> +
> /*
> * Just any arbitrary offset to the start of the vmalloc VM area: the
> * current 16MB value just means that there will be a 64MB "hole" after the
> diff --git a/arch/powerpc/include/asm/nohash/32/pgalloc.h b/arch/powerpc/include/asm/nohash/32/pgalloc.h
> index 77c09bef3122..bfb26c385dac 100644
> --- a/arch/powerpc/include/asm/nohash/32/pgalloc.h
> +++ b/arch/powerpc/include/asm/nohash/32/pgalloc.h
> @@ -60,6 +60,14 @@ static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp,
> *pmdp = __pmd(__pa(pte) | _PMD_PRESENT);
> }
>
> +#ifdef CONFIG_PPC_PMD_GUARDED
> +static inline void pmd_populate_kernel_g(struct mm_struct *mm, pmd_t *pmdp,
> + pte_t *pte)
> +{
> + *pmdp = __pmd(__pa(pte) | _PMD_PRESENT | _PMD_GUARDED);
> +}
> +#endif
> +
> static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmdp,
> pgtable_t pte_page)
> {
> @@ -84,6 +92,10 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmdp,
> #define pmd_pgtable(pmd) ((pgtable_t)pmd_page_vaddr(pmd))
> #endif
>
> +#ifndef CONFIG_PPC_PMD_GUARDED
> +#define pmd_populate_kernel_g pmd_populate_kernel
> +#endif
> +
> static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
> unsigned long address)
> {
> @@ -151,7 +163,7 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t table,
> pgtable_free_tlb(tlb, table, 0);
> }
>
> -static inline pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
> +static inline pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va, bool is_g)
> {
> if (!pmd_present(*pmdp)) {
> pte_t *ptep = __va(memblock_alloc(PTE_FRAG_SIZE, PTE_FRAG_SIZE));
> @@ -164,7 +176,10 @@ static inline pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
> else
> memset(ptep, 0, PTE_FRAG_SIZE);
>
> - pmd_populate_kernel(&init_mm, pmdp, ptep);
> + if (is_g)
> + pmd_populate_kernel_g(&init_mm, pmdp, ptep);
> + else
> + pmd_populate_kernel(&init_mm, pmdp, ptep);
> }
> return pte_offset_kernel(pmdp, va);
> }
> diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
> index dc82c10383d5..fccc5620a988 100644
> --- a/arch/powerpc/include/asm/nohash/32/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
> @@ -84,9 +84,14 @@ extern int icache_44x_need_flush;
> * virtual space that goes below PKMAP and FIXMAP
> */
> #ifdef CONFIG_HIGHMEM
> -#define KVIRT_TOP PKMAP_BASE
> +#define _KVIRT_TOP PKMAP_BASE
> #else
> -#define KVIRT_TOP (0xfe000000UL) /* for now, could be FIXMAP_BASE ? */
> +#define _KVIRT_TOP (0xfe000000UL) /* for now, could be FIXMAP_BASE ? */
> +#endif
> +#ifdef CONFIG_PPC_PMD_GUARDED
> +#define KVIRT_TOP _ALIGN_DOWN(_KVIRT_TOP, PGDIR_SIZE)
> +#else
> +#define KVIRT_TOP _KVIRT_TOP
> #endif
>
> /*
> @@ -99,6 +104,12 @@ extern int icache_44x_need_flush;
> #else
> #define IOREMAP_TOP KVIRT_TOP
> #endif
> +#ifdef CONFIG_PPC_PMD_GUARDED
> +#define IOREMAP_BASE _ALIGN_UP(VMALLOC_START + (IOREMAP_TOP - VMALLOC_START) / 2, \
> + PGDIR_SIZE)
> +#else
> +#define IOREMAP_BASE VMALLOC_START
> +#endif
>
> /*
> * Just any arbitrary offset to the start of the vmalloc VM area: the
> @@ -123,7 +134,11 @@ extern int icache_44x_need_flush;
> #else
> #define VMALLOC_START ((((long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
> #endif
> +#ifdef CONFIG_PPC_PMD_GUARDED
> +#define VMALLOC_END IOREMAP_BASE
> +#else
> #define VMALLOC_END ioremap_bot
> +#endif
>
> /*
> * Bits in a linux-style PTE. These match the bits in the
> diff --git a/arch/powerpc/mm/dump_linuxpagetables.c b/arch/powerpc/mm/dump_linuxpagetables.c
> index e60aa6d7456d..105d0118f735 100644
> --- a/arch/powerpc/mm/dump_linuxpagetables.c
> +++ b/arch/powerpc/mm/dump_linuxpagetables.c
> @@ -76,9 +76,9 @@ struct addr_marker {
>
> static struct addr_marker address_markers[] = {
> { 0, "Start of kernel VM" },
> +#ifdef CONFIG_PPC64
> { 0, "vmalloc() Area" },
> { 0, "vmalloc() End" },
> -#ifdef CONFIG_PPC64
> { 0, "isa I/O start" },
> { 0, "isa I/O end" },
> { 0, "phb I/O start" },
> @@ -87,8 +87,19 @@ static struct addr_marker address_markers[] = {
> { 0, "I/O remap end" },
> { 0, "vmemmap start" },
> #else
> +#ifdef CONFIG_PPC_PMD_GUARDED
> + { 0, "vmalloc() Area" },
> + { 0, "vmalloc() End" },
> + { 0, "Early I/O remap start" },
> + { 0, "Early I/O remap end" },
> + { 0, "I/O remap start" },
> + { 0, "I/O remap end" },
> +#else
> { 0, "Early I/O remap start" },
> { 0, "Early I/O remap end" },
> + { 0, "vmalloc() I/O remap start" },
> + { 0, "vmalloc() I/O remap end" },
> +#endif
> #ifdef CONFIG_NOT_COHERENT_CACHE
> { 0, "Consistent mem start" },
> { 0, "Consistent mem end" },
> @@ -286,9 +297,9 @@ static void populate_markers(void)
> int i = 0;
>
> address_markers[i++].start_address = PAGE_OFFSET;
> +#ifdef CONFIG_PPC64
> address_markers[i++].start_address = VMALLOC_START;
> address_markers[i++].start_address = VMALLOC_END;
> -#ifdef CONFIG_PPC64
> address_markers[i++].start_address = ISA_IO_BASE;
> address_markers[i++].start_address = ISA_IO_END;
> address_markers[i++].start_address = PHB_IO_BASE;
> @@ -301,6 +312,12 @@ static void populate_markers(void)
> address_markers[i++].start_address = VMEMMAP_BASE;
> #endif
> #else /* !CONFIG_PPC64 */
> +#ifdef CONFIG_PPC_PMD_GUARDED
> + address_markers[i++].start_address = VMALLOC_START;
> + address_markers[i++].start_address = VMALLOC_END;
> +#endif
> + address_markers[i++].start_address = IOREMAP_BASE;
> + address_markers[i++].start_address = ioremap_bot;
> address_markers[i++].start_address = ioremap_bot;
> address_markers[i++].start_address = IOREMAP_TOP;
> #ifdef CONFIG_NOT_COHERENT_CACHE
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index dd949d6649a2..1a4a20a95eaf 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -388,8 +388,15 @@ void __init mem_init(void)
> #endif /* CONFIG_NOT_COHERENT_CACHE */
> pr_info(" * 0x%08lx..0x%08lx : early ioremap\n",
> ioremap_bot, IOREMAP_TOP);
> +#ifdef CONFIG_PPC_PMD_GUARDED
> + pr_info(" * 0x%08lx..0x%08lx : ioremap\n",
> + IOREMAP_BASE, ioremap_bot);
> + pr_info(" * 0x%08lx..0x%08lx : vmalloc\n",
> + VMALLOC_START, VMALLOC_END);
> +#else
> pr_info(" * 0x%08lx..0x%08lx : vmalloc & ioremap\n",
> VMALLOC_START, VMALLOC_END);
> +#endif
> #endif /* CONFIG_PPC32 */
> }
>
> diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
> index 745f2f30d4e9..ce78c06db660 100644
> --- a/arch/powerpc/mm/pgtable_32.c
> +++ b/arch/powerpc/mm/pgtable_32.c
> @@ -151,7 +151,14 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *call
>
> if (slab_is_available()) {
> struct vm_struct *area;
> - area = get_vm_area_caller(size, VM_IOREMAP, caller);
> + bool is_g = pgprot_val(prot) & _PAGE_GUARDED;
> +
> + if (IS_ENABLED(CONFIG_PPC_PMD_GUARDED) && is_g)
> + area = __get_vm_area_caller(size, VM_IOREMAP, IOREMAP_BASE,
> + ioremap_bot, caller);
> + else
> + area = get_vm_area_caller(size, VM_IOREMAP, caller);
> +
> if (area == 0)
> return NULL;
> area->phys_addr = p;
> @@ -192,19 +199,54 @@ void iounmap(volatile void __iomem *addr)
> }
> EXPORT_SYMBOL(iounmap);
>
> +#ifdef CONFIG_PPC_PMD_GUARDED
> +static int __pte_alloc_kernel_g(pmd_t *pmd, unsigned long address)
> +{
> + pte_t *new = pte_alloc_one_kernel(&init_mm, address);
> + if (!new)
> + return -ENOMEM;
> +
> + smp_wmb(); /* See comment in __pte_alloc */
> +
> + spin_lock(&init_mm.page_table_lock);
> + if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
> + pmd_populate_kernel_g(&init_mm, pmd, new);
> + new = NULL;
> + }
> + spin_unlock(&init_mm.page_table_lock);
> + if (new)
> + pte_free_kernel(&init_mm, new);
> + return 0;
> +}
> +
> +static pte_t *pte_alloc_kernel_g(pmd_t *pmd, unsigned long address)
> +{
> + if (unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel_g(pmd, address))
> + return NULL;
> + return pte_offset_kernel(pmd, address);
> +}
> +#else
> +#define pte_alloc_kernel_g(pmd, address) pte_alloc_kernel(pmd, address)
> +#endif
> +
> __ref int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
> {
> pmd_t *pd;
> pte_t *pg;
> int err = -ENOMEM;
> + bool is_g = pgprot_val(prot) & _PAGE_GUARDED;
>
> /* Use upper 10 bits of VA to index the first level map */
> pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
> /* Use middle 10 bits of VA to index the second-level map */
> - if (slab_is_available())
> - pg = pte_alloc_kernel(pd, va);
> - else
> - pg = early_pte_alloc_kernel(pd, va);
> + if (slab_is_available()) {
> + if (is_g)
> + pg = pte_alloc_kernel_g(pd, va);
> + else
> + pg = pte_alloc_kernel(pd, va);
> + } else {
> + pg = early_pte_alloc_kernel(pd, va, is_g);
> + }
> if (pg != 0) {
> err = 0;
> /* The PTE should never be already set nor present in the
> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
> index 6c6a7c72cae4..d0984546fbec 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -355,6 +355,8 @@ config ARCH_ENABLE_HUGEPAGE_MIGRATION
> def_bool y
> depends on PPC_BOOK3S_64 && HUGETLB_PAGE && MIGRATION
>
> +config PPC_PMD_GUARDED
> + bool
>
> config PPC_MMU_NOHASH
> def_bool y
>
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