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[Xen-changelog] [xen-unstable] [IA64] add volatile to p2m table pte entry

From: Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>

Date: Mon, 03 Jul 2006 10:20:16 +0000

Delivery-date: Mon, 03 Jul 2006 03:24:37 -0700

List-id: BK change log <xen-changelog.lists.xensource.com>

# HG changeset patch # User awilliam@xxxxxxxxxxx # Node ID f02d59f9b11fa193b2030278a0b11e1982c421d3 # Parent dcb50b04faecd151b08cbff212bc4c00fa78da20 [IA64] add volatile to p2m table pte entry add volatile pte entry of the p2m table. Since p2m table are shared by cpu. volatile is needed. fix the races in pte access of __assign_domain_page() and destroy_grant_host_mapping() Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx> --- xen/arch/ia64/xen/mm.c | 145 +++++++++++++++++++-------- xen/include/asm-ia64/linux-xen/asm/pgtable.h | 15 ++ 2 files changed, 117 insertions(+), 43 deletions(-) diff -r dcb50b04faec -r f02d59f9b11f xen/arch/ia64/xen/mm.c --- a/xen/arch/ia64/xen/mm.c Mon Jun 19 12:13:11 2006 -0600 +++ b/xen/arch/ia64/xen/mm.c Mon Jun 19 12:52:38 2006 -0600 @@ -338,10 +338,42 @@ unsigned long translate_domain_mpaddr(un } //XXX !xxx_present() should be used instread of !xxx_none()? +// __assign_new_domain_page(), assign_new_domain_page() and +// assign_new_domain0_page() are used only when domain creation. +// their accesses aren't racy so that returned pte_t doesn't need +// volatile qualifier +static pte_t* +__lookup_alloc_domain_pte(struct domain* d, unsigned long mpaddr) +{ + struct mm_struct *mm = &d->arch.mm; + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + + BUG_ON(mm->pgd == NULL); + pgd = pgd_offset(mm, mpaddr); + if (pgd_none(*pgd)) { + pgd_populate(mm, pgd, pud_alloc_one(mm,mpaddr)); + } + + pud = pud_offset(pgd, mpaddr); + if (pud_none(*pud)) { + pud_populate(mm, pud, pmd_alloc_one(mm,mpaddr)); + } + + pmd = pmd_offset(pud, mpaddr); + if (pmd_none(*pmd)) { + pmd_populate_kernel(mm, pmd, pte_alloc_one_kernel(mm, mpaddr)); + } + + return pte_offset_map(pmd, mpaddr); +} + +//XXX !xxx_present() should be used instread of !xxx_none()? // pud, pmd, pte page is zero cleared when they are allocated. // Their area must be visible before population so that // cmpxchg must have release semantics. -static pte_t* +static volatile pte_t* lookup_alloc_domain_pte(struct domain* d, unsigned long mpaddr) { struct mm_struct *mm = &d->arch.mm; @@ -384,11 +416,11 @@ lookup_alloc_domain_pte(struct domain* d } } - return pte_offset_map(pmd, mpaddr); + return (volatile pte_t*)pte_offset_map(pmd, mpaddr); } //XXX xxx_none() should be used instread of !xxx_present()? -static pte_t* +static volatile pte_t* lookup_noalloc_domain_pte(struct domain* d, unsigned long mpaddr) { struct mm_struct *mm = &d->arch.mm; @@ -409,11 +441,11 @@ lookup_noalloc_domain_pte(struct domain* if (unlikely(!pmd_present(*pmd))) return NULL; - return pte_offset_map(pmd, mpaddr); + return (volatile pte_t*)pte_offset_map(pmd, mpaddr); } #ifdef CONFIG_XEN_IA64_DOM0_VP -static pte_t* +static volatile pte_t* lookup_noalloc_domain_pte_none(struct domain* d, unsigned long mpaddr) { struct mm_struct *mm = &d->arch.mm; @@ -434,13 +466,13 @@ lookup_noalloc_domain_pte_none(struct do if (unlikely(pmd_none(*pmd))) return NULL; - return pte_offset_map(pmd, mpaddr); + return (volatile pte_t*)pte_offset_map(pmd, mpaddr); } unsigned long ____lookup_domain_mpa(struct domain *d, unsigned long mpaddr) { - pte_t *pte; + volatile pte_t *pte; pte = lookup_noalloc_domain_pte(d, mpaddr); if (pte == NULL) @@ -470,7 +502,7 @@ __lookup_domain_mpa(struct domain *d, un unsigned long lookup_domain_mpa(struct domain *d, unsigned long mpaddr) { - pte_t *pte; + volatile pte_t *pte; #ifdef CONFIG_DOMAIN0_CONTIGUOUS if (d == dom0) { @@ -486,9 +518,10 @@ unsigned long lookup_domain_mpa(struct d #endif pte = lookup_noalloc_domain_pte(d, mpaddr); if (pte != NULL) { - if (pte_present(*pte)) { + pte_t tmp_pte = *pte;// pte is volatile. copy the value. + if (pte_present(tmp_pte)) { //printk("lookup_domain_page: found mapping for %lx, pte=%lx\n",mpaddr,pte_val(*pte)); - return pte_val(*pte); + return pte_val(tmp_pte); } else if (VMX_DOMAIN(d->vcpu[0])) return GPFN_INV_MASK; } @@ -530,7 +563,7 @@ void *domain_mpa_to_imva(struct domain * /* Allocate a new page for domain and map it to the specified metaphysical address. */ -struct page_info * +static struct page_info * __assign_new_domain_page(struct domain *d, unsigned long mpaddr, pte_t* pte) { struct page_info *p = NULL; @@ -595,7 +628,7 @@ assign_new_domain_page(struct domain *d, struct page_info *p = NULL; pte_t *pte; - pte = lookup_alloc_domain_pte(d, mpaddr); + pte = __lookup_alloc_domain_pte(d, mpaddr); if (pte_none(*pte)) p = __assign_new_domain_page(d, mpaddr, pte); @@ -610,7 +643,7 @@ assign_new_domain0_page(struct domain *d pte_t *pte; BUG_ON(d != dom0); - pte = lookup_alloc_domain_pte(d, mpaddr); + pte = __lookup_alloc_domain_pte(d, mpaddr); if (pte_none(*pte)) { struct page_info *p = __assign_new_domain_page(d, mpaddr, pte); if (p == NULL) { @@ -622,21 +655,27 @@ assign_new_domain0_page(struct domain *d /* map a physical address to the specified metaphysical addr */ // flags: currently only ASSIGN_readonly +// This is called by assign_domain_mmio_page(). +// So accessing to pte is racy. void __assign_domain_page(struct domain *d, unsigned long mpaddr, unsigned long physaddr, unsigned long flags) { - pte_t *pte; + volatile pte_t *pte; + pte_t old_pte; + pte_t new_pte; + pte_t ret_pte; unsigned long arflags = (flags & ASSIGN_readonly)? _PAGE_AR_R: _PAGE_AR_RWX; pte = lookup_alloc_domain_pte(d, mpaddr); - if (pte_none(*pte)) { - set_pte_rel(pte, - pfn_pte(physaddr >> PAGE_SHIFT, - __pgprot(__DIRTY_BITS | _PAGE_PL_2 | arflags))); + + old_pte = __pte(0); + new_pte = pfn_pte(physaddr >> PAGE_SHIFT, + __pgprot(__DIRTY_BITS | _PAGE_PL_2 | arflags)); + ret_pte = ptep_cmpxchg_rel(&d->arch.mm, mpaddr, pte, old_pte, new_pte); + if (pte_val(ret_pte) == pte_val(old_pte)) smp_mb(); - } } /* get_page() and map a physical address to the specified metaphysical addr */ @@ -755,7 +794,7 @@ assign_domain_page_replace(struct domain unsigned long mfn, unsigned long flags) { struct mm_struct *mm = &d->arch.mm; - pte_t* pte; + volatile pte_t* pte; pte_t old_pte; pte_t npte; unsigned long arflags = (flags & ASSIGN_readonly)? _PAGE_AR_R: _PAGE_AR_RWX; @@ -798,7 +837,7 @@ assign_domain_page_cmpxchg_rel(struct do unsigned long flags) { struct mm_struct *mm = &d->arch.mm; - pte_t* pte; + volatile pte_t* pte; unsigned long old_mfn; unsigned long old_arflags; pte_t old_pte; @@ -810,9 +849,14 @@ assign_domain_page_cmpxchg_rel(struct do pte = lookup_alloc_domain_pte(d, mpaddr); again: - old_arflags = pte_val(*pte) & ~_PAGE_PPN_MASK;//XXX + old_arflags = pte_val(*pte) & ~_PAGE_PPN_MASK; old_mfn = page_to_mfn(old_page); old_pte = pfn_pte(old_mfn, __pgprot(old_arflags)); + if (!pte_present(old_pte)) { + DPRINTK("%s: old_pte 0x%lx old_arflags 0x%lx old_mfn 0x%lx\n", + __func__, pte_val(old_pte), old_arflags, old_mfn); + return -EINVAL; + } new_arflags = (flags & ASSIGN_readonly)? _PAGE_AR_R: _PAGE_AR_RWX; new_mfn = page_to_mfn(new_page); @@ -850,7 +894,7 @@ zap_domain_page_one(struct domain *d, un zap_domain_page_one(struct domain *d, unsigned long mpaddr) { struct mm_struct *mm = &d->arch.mm; - pte_t *pte; + volatile pte_t *pte; pte_t old_pte; unsigned long mfn; struct page_info *page; @@ -970,10 +1014,12 @@ destroy_grant_host_mapping(unsigned long unsigned long mfn, unsigned int flags) { struct domain* d = current->domain; - pte_t* pte; + volatile pte_t* pte; + unsigned long cur_arflags; + pte_t cur_pte; + pte_t new_pte; pte_t old_pte; - unsigned long old_mfn = INVALID_MFN; - struct page_info* old_page; + struct page_info* page; if (flags & (GNTMAP_application_map | GNTMAP_contains_pte)) { DPRINTK("%s: flags 0x%x\n", __func__, flags); @@ -981,21 +1027,42 @@ destroy_grant_host_mapping(unsigned long } pte = lookup_noalloc_domain_pte(d, gpaddr); - if (pte == NULL || !pte_present(*pte) || pte_pfn(*pte) != mfn) + if (pte == NULL) { + DPRINTK("%s: gpaddr 0x%lx mfn 0x%lx\n", __func__, gpaddr, mfn); return GNTST_general_error; - - // update pte - old_pte = ptep_get_and_clear(&d->arch.mm, gpaddr, pte); - if (pte_present(old_pte)) { - old_mfn = pte_pfn(old_pte); - } else { + } + + again: + cur_arflags = pte_val(*pte) & ~_PAGE_PPN_MASK; + cur_pte = pfn_pte(mfn, __pgprot(cur_arflags)); + if (!pte_present(cur_pte)) { + DPRINTK("%s: gpaddr 0x%lx mfn 0x%lx cur_pte 0x%lx\n", + __func__, gpaddr, mfn, pte_val(cur_pte)); return GNTST_general_error; } - domain_page_flush(d, gpaddr, old_mfn, INVALID_MFN); - - old_page = mfn_to_page(old_mfn); - BUG_ON(page_get_owner(old_page) == d);//try_to_clear_PGC_allocate(d, page) is not needed. - put_page(old_page); + new_pte = __pte(0); + + old_pte = ptep_cmpxchg_rel(&d->arch.mm, gpaddr, pte, cur_pte, new_pte); + if (unlikely(!pte_present(old_pte))) { + DPRINTK("%s: gpaddr 0x%lx mfn 0x%lx cur_pte 0x%lx old_pte 0x%lx\n", + __func__, gpaddr, mfn, pte_val(cur_pte), pte_val(old_pte)); + return GNTST_general_error; + } + if (unlikely(pte_val(cur_pte) != pte_val(old_pte))) { + if (pte_pfn(old_pte) == mfn) { + goto again; + } + DPRINTK("%s gpaddr 0x%lx mfn 0x%lx cur_pte 0x%lx old_pte 0x%lx\n", + __func__, gpaddr, mfn, pte_val(cur_pte), pte_val(old_pte)); + return GNTST_general_error; + } + BUG_ON(pte_pfn(old_pte) != mfn); + + domain_page_flush(d, gpaddr, mfn, INVALID_MFN); + + page = mfn_to_page(mfn); + BUG_ON(page_get_owner(page) == d);//try_to_clear_PGC_allocate(d, page) is not needed. + put_page(page); return GNTST_okay; } @@ -1141,7 +1208,7 @@ int int domain_page_mapped(struct domain* d, unsigned long mpaddr) { - pte_t * pte; + volatile pte_t * pte; pte = lookup_noalloc_domain_pte(d, mpaddr); if(pte != NULL && !pte_none(*pte)) diff -r dcb50b04faec -r f02d59f9b11f xen/include/asm-ia64/linux-xen/asm/pgtable.h --- a/xen/include/asm-ia64/linux-xen/asm/pgtable.h Mon Jun 19 12:13:11 2006 -0600 +++ b/xen/include/asm-ia64/linux-xen/asm/pgtable.h Mon Jun 19 12:52:38 2006 -0600 @@ -210,7 +210,7 @@ ia64_phys_addr_valid (unsigned long addr #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval) #ifdef XEN static inline void -set_pte_rel(pte_t* ptep, pte_t pteval) +set_pte_rel(volatile pte_t* ptep, pte_t pteval) { #if CONFIG_SMP asm volatile ("st8.rel [%0]=%1" :: @@ -402,8 +402,14 @@ ptep_test_and_clear_dirty (struct vm_are } #endif +#ifdef XEN +static inline pte_t +ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, + volatile pte_t *ptep) +#else static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) +#endif { #ifdef CONFIG_SMP return __pte(xchg((long *) ptep, 0)); @@ -416,7 +422,8 @@ ptep_get_and_clear(struct mm_struct *mm, #ifdef XEN static inline pte_t -ptep_xchg(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t npte) +ptep_xchg(struct mm_struct *mm, unsigned long addr, + volatile pte_t *ptep, pte_t npte) { #ifdef CONFIG_SMP return __pte(xchg((long *) ptep, pte_val(npte))); @@ -428,8 +435,8 @@ ptep_xchg(struct mm_struct *mm, unsigned } static inline pte_t -ptep_cmpxchg_rel(struct mm_struct *mm, unsigned long addr, pte_t *ptep, - pte_t old_pte, pte_t new_pte) +ptep_cmpxchg_rel(struct mm_struct *mm, unsigned long addr, + volatile pte_t *ptep, pte_t old_pte, pte_t new_pte) { #ifdef CONFIG_SMP return __pte(cmpxchg_rel(&pte_val(*ptep), _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-changelog

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