[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@valinux.co.jp>

diff --git a/xen/arch/ia64/xen/mm.c b/xen/arch/ia64/xen/mm.c
index 96c64dc5a3bcde0b484c08247a235926a385fdb0..ac70b9663b177950a0af968a523132ea03780c52 100644 (file)
--- a/xen/arch/ia64/xen/mm.c
+++ b/xen/arch/ia64/xen/mm.c
@@ -337,11 +337,43 @@ unsigned long translate_domain_mpaddr(unsigned long mpaddr)
        return ((pteval & _PAGE_PPN_MASK) | (mpaddr & ~PAGE_MASK));
 }
 
+//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, unsigned long mpaddr)
         }
     }
 
-    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* d, unsigned long mpaddr)
     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 domain* d, unsigned long mpaddr)
     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, unsigned long mpaddr)
 
 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 domain *d, unsigned long mpaddr)
 #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 *d, unsigned long mpaddr)
 
 /* 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, unsigned long mpaddr)
     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, unsigned long mpaddr)
     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, unsigned long mpaddr)
 
 /* 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 *d, unsigned long mpaddr,
                            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 domain* d, unsigned long mpaddr,
                                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 domain* d, unsigned long mpaddr,
     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 @@ static void
 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 gpaddr,
                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 gpaddr,
     }
 
     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);
+    new_pte = __pte(0);
 
-    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);
+    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 @@ domain_page_flush(struct domain* d, unsigned long mpaddr,
 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 --git a/xen/include/asm-ia64/linux-xen/asm/pgtable.h b/xen/include/asm-ia64/linux-xen/asm/pgtable.h
index 136076c4111f511aa4f1115a3daf2be42d235fcf..c0fd80652c9b1d9cf3d3154dc3f84fd3b814c0d1 100644 (file)
--- a/xen/include/asm-ia64/linux-xen/asm/pgtable.h
+++ b/xen/include/asm-ia64/linux-xen/asm/pgtable.h
@@ -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_area_struct *vma, unsigned long addr, pte_t
 }
 #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, unsigned long addr, pte_t *ptep)
 
 #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 long addr, pte_t *ptep, pte_t npte)
 }
 
 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),