The VMI backend uses explicit page type notification to track shadow page tables. The allocation of page table roots is especially tricky. We want to clone the root for non-PAE mode while it is protected under the pgd lock. Signed-off-by: Zachary Amsden <zach@vmware.com> ==================================================================--- a/arch/i386/kernel/paravirt.c +++ b/arch/i386/kernel/paravirt.c @@ -545,6 +545,12 @@ 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, ==================================================================--- a/arch/i386/mm/init.c +++ b/arch/i386/mm/init.c @@ -62,6 +62,7 @@ static pmd_t * __init one_md_table_init( #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_ini { 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(); @@ -347,6 +349,8 @@ 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 */ ==================================================================--- a/arch/i386/mm/pageattr.c +++ b/arch/i386/mm/pageattr.c @@ -60,6 +60,7 @@ static struct page *split_large_page(uns 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)); @@ -166,6 +167,7 @@ __change_page_attr(struct page *page, pg 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); } ==================================================================--- a/arch/i386/mm/pgtable.c +++ b/arch/i386/mm/pgtable.c @@ -245,8 +245,14 @@ void pgd_ctor(void *pgd, kmem_cache_t *c 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); @@ -257,6 +263,7 @@ void pgd_dtor(void *pgd, kmem_cache_t *c { 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); @@ -274,13 +281,18 @@ 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; } @@ -291,8 +303,12 @@ 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); } ==================================================================--- a/include/asm-i386/paravirt.h +++ b/include/asm-i386/paravirt.h @@ -126,6 +126,12 @@ struct paravirt_ops void (fastcall *flush_tlb_user)(void); 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); @@ -325,6 +331,14 @@ static __inline unsigned long apic_read( #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); ==================================================================--- a/include/asm-i386/pgalloc.h +++ b/include/asm-i386/pgalloc.h @@ -5,13 +5,31 @@ #include <linux/threads.h> #include <linux/mm.h> /* for struct page */ -#define pmd_populate_kernel(mm, pmd, pte) \ - set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte))) +#ifdef CONFIG_PARAVIRT +#include <asm/paravirt.h> +#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 } -#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 /*