From c119ecce894120790903ef535dac3e105f3d6cde Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Tue, 13 Feb 2007 13:26:21 +0100 Subject: [PATCH] [PATCH] MM: page allocation hooks for VMI backend The VMI backend uses explicit page type notification to track shadow page tables. The allocation of page table roots is especially tricky. We need to clone the root for non-PAE mode while it is protected under the pgd lock to correctly copy the shadow. We don't need to allocate pgds in PAE mode, (PDPs in Intel terminology) as they only have 4 entries, and are cached entirely by the processor, which makes shadowing them rather simple. For base page table level allocation, pmd_populate provides the exact hook point we need. Also, we need to allocate pages when splitting a large page, and we must release pages before returning the page to any free pool. Despite being required with these slightly odd semantics for VMI, Xen also uses these hooks to determine the exact moment when page tables are created or released. AK: All nops for other architectures Signed-off-by: Zachary Amsden Signed-off-by: Andi Kleen Cc: Andi Kleen Cc: Jeremy Fitzhardinge Cc: Rusty Russell Cc: Chris Wright Signed-off-by: Andrew Morton --- arch/i386/kernel/paravirt.c | 6 ++++++ arch/i386/mm/init.c | 4 ++++ arch/i386/mm/pageattr.c | 2 ++ arch/i386/mm/pgtable.c | 24 ++++++++++++++++++++---- include/asm-i386/paravirt.h | 14 ++++++++++++++ include/asm-i386/pgalloc.h | 30 ++++++++++++++++++++++++++---- 6 files changed, 72 insertions(+), 8 deletions(-) diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c index e55fd05da0..7329ec9fcc 100644 --- a/arch/i386/kernel/paravirt.c +++ b/arch/i386/kernel/paravirt.c @@ -550,6 +550,12 @@ struct paravirt_ops paravirt_ops = { .flush_tlb_kernel = native_flush_tlb_global, .flush_tlb_single = native_flush_tlb_single, + .alloc_pt = (void *)native_nop, + .alloc_pd = (void *)native_nop, + .alloc_pd_clone = (void *)native_nop, + .release_pt = (void *)native_nop, + .release_pd = (void *)native_nop, + .set_pte = native_set_pte, .set_pte_at = native_set_pte_at, .set_pmd = native_set_pmd, diff --git a/arch/i386/mm/init.c b/arch/i386/mm/init.c index c5c5ea700c..ae436882af 100644 --- a/arch/i386/mm/init.c +++ b/arch/i386/mm/init.c @@ -62,6 +62,7 @@ static pmd_t * __init one_md_table_init(pgd_t *pgd) #ifdef CONFIG_X86_PAE pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE); + paravirt_alloc_pd(__pa(pmd_table) >> PAGE_SHIFT); set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT)); pud = pud_offset(pgd, 0); if (pmd_table != pmd_offset(pud, 0)) @@ -82,6 +83,7 @@ static pte_t * __init one_page_table_init(pmd_t *pmd) { if (pmd_none(*pmd)) { pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE); + paravirt_alloc_pt(__pa(page_table) >> PAGE_SHIFT); set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE)); if (page_table != pte_offset_kernel(pmd, 0)) BUG(); @@ -345,6 +347,8 @@ static void __init pagetable_init (void) /* Init entries of the first-level page table to the zero page */ for (i = 0; i < PTRS_PER_PGD; i++) set_pgd(pgd_base + i, __pgd(__pa(empty_zero_page) | _PAGE_PRESENT)); +#else + paravirt_alloc_pd(__pa(swapper_pg_dir) >> PAGE_SHIFT); #endif /* Enable PSE if available */ diff --git a/arch/i386/mm/pageattr.c b/arch/i386/mm/pageattr.c index e223b1d498..412ebbd8ad 100644 --- a/arch/i386/mm/pageattr.c +++ b/arch/i386/mm/pageattr.c @@ -60,6 +60,7 @@ static struct page *split_large_page(unsigned long address, pgprot_t prot, address = __pa(address); addr = address & LARGE_PAGE_MASK; pbase = (pte_t *)page_address(base); + paravirt_alloc_pt(page_to_pfn(base)); for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) { set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, addr == address ? prot : ref_prot)); @@ -172,6 +173,7 @@ __change_page_attr(struct page *page, pgprot_t prot) if (!PageReserved(kpte_page)) { if (cpu_has_pse && (page_private(kpte_page) == 0)) { ClearPagePrivate(kpte_page); + paravirt_release_pt(page_to_pfn(kpte_page)); list_add(&kpte_page->lru, &df_list); revert_page(kpte_page, address); } diff --git a/arch/i386/mm/pgtable.c b/arch/i386/mm/pgtable.c index f349eaf450..b5f538f522 100644 --- a/arch/i386/mm/pgtable.c +++ b/arch/i386/mm/pgtable.c @@ -248,9 +248,15 @@ void pgd_ctor(void *pgd, struct kmem_cache *cache, unsigned long unused) clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD, swapper_pg_dir + USER_PTRS_PER_PGD, KERNEL_PGD_PTRS); + if (PTRS_PER_PMD > 1) return; + /* must happen under lock */ + paravirt_alloc_pd_clone(__pa(pgd) >> PAGE_SHIFT, + __pa(swapper_pg_dir) >> PAGE_SHIFT, + USER_PTRS_PER_PGD, PTRS_PER_PGD - USER_PTRS_PER_PGD); + pgd_list_add(pgd); spin_unlock_irqrestore(&pgd_lock, flags); } @@ -260,6 +266,7 @@ void pgd_dtor(void *pgd, struct kmem_cache *cache, unsigned long unused) { unsigned long flags; /* can be called from interrupt context */ + paravirt_release_pd(__pa(pgd) >> PAGE_SHIFT); spin_lock_irqsave(&pgd_lock, flags); pgd_list_del(pgd); spin_unlock_irqrestore(&pgd_lock, flags); @@ -277,13 +284,18 @@ pgd_t *pgd_alloc(struct mm_struct *mm) pmd_t *pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL); if (!pmd) goto out_oom; + paravirt_alloc_pd(__pa(pmd) >> PAGE_SHIFT); set_pgd(&pgd[i], __pgd(1 + __pa(pmd))); } return pgd; out_oom: - for (i--; i >= 0; i--) - kmem_cache_free(pmd_cache, (void *)__va(pgd_val(pgd[i])-1)); + for (i--; i >= 0; i--) { + pgd_t pgdent = pgd[i]; + void* pmd = (void *)__va(pgd_val(pgdent)-1); + paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT); + kmem_cache_free(pmd_cache, pmd); + } kmem_cache_free(pgd_cache, pgd); return NULL; } @@ -294,8 +306,12 @@ void pgd_free(pgd_t *pgd) /* in the PAE case user pgd entries are overwritten before usage */ if (PTRS_PER_PMD > 1) - for (i = 0; i < USER_PTRS_PER_PGD; ++i) - kmem_cache_free(pmd_cache, (void *)__va(pgd_val(pgd[i])-1)); + for (i = 0; i < USER_PTRS_PER_PGD; ++i) { + pgd_t pgdent = pgd[i]; + void* pmd = (void *)__va(pgd_val(pgdent)-1); + paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT); + kmem_cache_free(pmd_cache, pmd); + } /* in the non-PAE case, free_pgtables() clears user pgd entries */ kmem_cache_free(pgd_cache, pgd); } diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h index 9f06265065..53da276a2e 100644 --- a/include/asm-i386/paravirt.h +++ b/include/asm-i386/paravirt.h @@ -127,6 +127,12 @@ struct paravirt_ops void (fastcall *flush_tlb_kernel)(void); void (fastcall *flush_tlb_single)(u32 addr); + void (fastcall *alloc_pt)(u32 pfn); + void (fastcall *alloc_pd)(u32 pfn); + void (fastcall *alloc_pd_clone)(u32 pfn, u32 clonepfn, u32 start, u32 count); + void (fastcall *release_pt)(u32 pfn); + void (fastcall *release_pd)(u32 pfn); + void (fastcall *set_pte)(pte_t *ptep, pte_t pteval); void (fastcall *set_pte_at)(struct mm_struct *mm, u32 addr, pte_t *ptep, pte_t pteval); void (fastcall *set_pmd)(pmd_t *pmdp, pmd_t pmdval); @@ -320,6 +326,14 @@ static inline unsigned long apic_read(unsigned long reg) #define __flush_tlb_global() paravirt_ops.flush_tlb_kernel() #define __flush_tlb_single(addr) paravirt_ops.flush_tlb_single(addr) +#define paravirt_alloc_pt(pfn) paravirt_ops.alloc_pt(pfn) +#define paravirt_release_pt(pfn) paravirt_ops.release_pt(pfn) + +#define paravirt_alloc_pd(pfn) paravirt_ops.alloc_pd(pfn) +#define paravirt_alloc_pd_clone(pfn, clonepfn, start, count) \ + paravirt_ops.alloc_pd_clone(pfn, clonepfn, start, count) +#define paravirt_release_pd(pfn) paravirt_ops.release_pd(pfn) + static inline void set_pte(pte_t *ptep, pte_t pteval) { paravirt_ops.set_pte(ptep, pteval); diff --git a/include/asm-i386/pgalloc.h b/include/asm-i386/pgalloc.h index 4b1e61359f..c8dc2d0141 100644 --- a/include/asm-i386/pgalloc.h +++ b/include/asm-i386/pgalloc.h @@ -5,13 +5,31 @@ #include #include /* for struct page */ -#define pmd_populate_kernel(mm, pmd, pte) \ - set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte))) +#ifdef CONFIG_PARAVIRT +#include +#else +#define paravirt_alloc_pt(pfn) do { } while (0) +#define paravirt_alloc_pd(pfn) do { } while (0) +#define paravirt_alloc_pd(pfn) do { } while (0) +#define paravirt_alloc_pd_clone(pfn, clonepfn, start, count) do { } while (0) +#define paravirt_release_pt(pfn) do { } while (0) +#define paravirt_release_pd(pfn) do { } while (0) +#endif + +#define pmd_populate_kernel(mm, pmd, pte) \ +do { \ + paravirt_alloc_pt(__pa(pte) >> PAGE_SHIFT); \ + set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte))); \ +} while (0) #define pmd_populate(mm, pmd, pte) \ +do { \ + paravirt_alloc_pt(page_to_pfn(pte)); \ set_pmd(pmd, __pmd(_PAGE_TABLE + \ ((unsigned long long)page_to_pfn(pte) << \ - (unsigned long long) PAGE_SHIFT))) + (unsigned long long) PAGE_SHIFT))); \ +} while (0) + /* * Allocate and free page tables. */ @@ -32,7 +50,11 @@ static inline void pte_free(struct page *pte) } -#define __pte_free_tlb(tlb,pte) tlb_remove_page((tlb),(pte)) +#define __pte_free_tlb(tlb,pte) \ +do { \ + paravirt_release_pt(page_to_pfn(pte)); \ + tlb_remove_page((tlb),(pte)); \ +} while (0) #ifdef CONFIG_X86_PAE /* -- 2.39.5