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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [IA64] page ref counter
# HG changeset patch
# User awilliam@xxxxxxxxxxx
# Node ID c644eb4049abedac4bbe83c0497b592b1f4bb531
# Parent 405f0f847c0f33381c69a04a168f34150a2bca7d
[IA64] page ref counter
Signed-off-by: Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>
Signed-off-by: Masaki Kanno <kanno.masaki@xxxxxxxxxxxxxx>
diff -r 405f0f847c0f -r c644eb4049ab xen/arch/ia64/xen/xenmisc.c
--- a/xen/arch/ia64/xen/xenmisc.c Thu Mar 9 23:24:31 2006
+++ b/xen/arch/ia64/xen/xenmisc.c Fri Mar 10 15:23:39 2006
@@ -147,12 +147,17 @@
//memset(percpu_info, 0, sizeof(percpu_info));
}
-#if 0
-void free_page_type(struct page_info *page, unsigned int type)
-{
- dummy();
-}
-#endif
+void free_page_type(struct page_info *page, u32 type)
+{
+// dummy();
+ return;
+}
+
+int alloc_page_type(struct page_info *page, u32 type)
+{
+// dummy();
+ return 1;
+}
///////////////////////////////
//// misc memory stuff
@@ -415,3 +420,203 @@
}
else printk("sync_split_caches ignored for CPU with no split cache\n");
}
+
+///////////////////////////////
+// from arch/x86/mm.c
+///////////////////////////////
+
+#ifdef VERBOSE
+#define MEM_LOG(_f, _a...) \
+ printk("DOM%u: (file=mm.c, line=%d) " _f "\n", \
+ current->domain->domain_id , __LINE__ , ## _a )
+#else
+#define MEM_LOG(_f, _a...) ((void)0)
+#endif
+
+void cleanup_writable_pagetable(struct domain *d)
+{
+ return;
+}
+
+void put_page_type(struct page_info *page)
+{
+ u32 nx, x, y = page->u.inuse.type_info;
+
+ again:
+ do {
+ x = y;
+ nx = x - 1;
+
+ ASSERT((x & PGT_count_mask) != 0);
+
+ /*
+ * The page should always be validated while a reference is held. The
+ * exception is during domain destruction, when we forcibly invalidate
+ * page-table pages if we detect a referential loop.
+ * See domain.c:relinquish_list().
+ */
+ ASSERT((x & PGT_validated) ||
+ test_bit(_DOMF_dying, &page_get_owner(page)->domain_flags));
+
+ if ( unlikely((nx & PGT_count_mask) == 0) )
+ {
+ /* Record TLB information for flush later. Races are harmless. */
+ page->tlbflush_timestamp = tlbflush_current_time();
+
+ if ( unlikely((nx & PGT_type_mask) <= PGT_l4_page_table) &&
+ likely(nx & PGT_validated) )
+ {
+ /*
+ * Page-table pages must be unvalidated when count is zero. The
+ * 'free' is safe because the refcnt is non-zero and validated
+ * bit is clear => other ops will spin or fail.
+ */
+ if ( unlikely((y = cmpxchg(&page->u.inuse.type_info, x,
+ x & ~PGT_validated)) != x) )
+ goto again;
+ /* We cleared the 'valid bit' so we do the clean up. */
+ free_page_type(page, x);
+ /* Carry on, but with the 'valid bit' now clear. */
+ x &= ~PGT_validated;
+ nx &= ~PGT_validated;
+ }
+ }
+ else if ( unlikely(((nx & (PGT_pinned | PGT_count_mask)) ==
+ (PGT_pinned | 1)) &&
+ ((nx & PGT_type_mask) != PGT_writable_page)) )
+ {
+ /* Page is now only pinned. Make the back pointer mutable again. */
+ nx |= PGT_va_mutable;
+ }
+ }
+ while ( unlikely((y = cmpxchg(&page->u.inuse.type_info, x, nx)) != x) );
+}
+
+
+int get_page_type(struct page_info *page, u32 type)
+{
+ u32 nx, x, y = page->u.inuse.type_info;
+
+ again:
+ do {
+ x = y;
+ nx = x + 1;
+ if ( unlikely((nx & PGT_count_mask) == 0) )
+ {
+ MEM_LOG("Type count overflow on pfn %lx", page_to_mfn(page));
+ return 0;
+ }
+ else if ( unlikely((x & PGT_count_mask) == 0) )
+ {
+ if ( (x & (PGT_type_mask|PGT_va_mask)) != type )
+ {
+ if ( (x & PGT_type_mask) != (type & PGT_type_mask) )
+ {
+ /*
+ * On type change we check to flush stale TLB
+ * entries. This may be unnecessary (e.g., page
+ * was GDT/LDT) but those circumstances should be
+ * very rare.
+ */
+ cpumask_t mask =
+ page_get_owner(page)->domain_dirty_cpumask;
+ tlbflush_filter(mask, page->tlbflush_timestamp);
+
+ if ( unlikely(!cpus_empty(mask)) )
+ {
+ perfc_incrc(need_flush_tlb_flush);
+ flush_tlb_mask(mask);
+ }
+ }
+
+ /* We lose existing type, back pointer, and validity. */
+ nx &= ~(PGT_type_mask | PGT_va_mask | PGT_validated);
+ nx |= type;
+
+ /* No special validation needed for writable pages. */
+ /* Page tables and GDT/LDT need to be scanned for validity. */
+ if ( type == PGT_writable_page )
+ nx |= PGT_validated;
+ }
+ }
+ else
+ {
+ if ( unlikely((x & (PGT_type_mask|PGT_va_mask)) != type) )
+ {
+ if ( unlikely((x & PGT_type_mask) != (type & PGT_type_mask) ) )
+ {
+ if ( current->domain == page_get_owner(page) )
+ {
+ /*
+ * This ensures functions like set_gdt() see up-to-date
+ * type info without needing to clean up writable p.t.
+ * state on the fast path.
+ */
+ LOCK_BIGLOCK(current->domain);
+ cleanup_writable_pagetable(current->domain);
+ y = page->u.inuse.type_info;
+ UNLOCK_BIGLOCK(current->domain);
+ /* Can we make progress now? */
+ if ( ((y & PGT_type_mask) == (type & PGT_type_mask)) ||
+ ((y & PGT_count_mask) == 0) )
+ goto again;
+ }
+ if ( ((x & PGT_type_mask) != PGT_l2_page_table) ||
+ ((type & PGT_type_mask) != PGT_l1_page_table) )
+ MEM_LOG("Bad type (saw %" PRtype_info
+ " != exp %" PRtype_info ") "
+ "for mfn %lx (pfn %lx)",
+ x, type, page_to_mfn(page),
+ get_gpfn_from_mfn(page_to_mfn(page)));
+ return 0;
+ }
+ else if ( (x & PGT_va_mask) == PGT_va_mutable )
+ {
+ /* The va backpointer is mutable, hence we update it. */
+ nx &= ~PGT_va_mask;
+ nx |= type; /* we know the actual type is correct */
+ }
+ else if ( ((type & PGT_va_mask) != PGT_va_mutable) &&
+ ((type & PGT_va_mask) != (x & PGT_va_mask)) )
+ {
+#ifdef CONFIG_X86_PAE
+ /* We use backptr as extra typing. Cannot be unknown. */
+ if ( (type & PGT_type_mask) == PGT_l2_page_table )
+ return 0;
+#endif
+ /* This table is possibly mapped at multiple locations. */
+ nx &= ~PGT_va_mask;
+ nx |= PGT_va_unknown;
+ }
+ }
+ if ( unlikely(!(x & PGT_validated)) )
+ {
+ /* Someone else is updating validation of this page. Wait... */
+ while ( (y = page->u.inuse.type_info) == x )
+ cpu_relax();
+ goto again;
+ }
+ }
+ }
+ while ( unlikely((y = cmpxchg(&page->u.inuse.type_info, x, nx)) != x) );
+
+ if ( unlikely(!(nx & PGT_validated)) )
+ {
+ /* Try to validate page type; drop the new reference on failure. */
+ if ( unlikely(!alloc_page_type(page, type)) )
+ {
+ MEM_LOG("Error while validating mfn %lx (pfn %lx) for type %"
+ PRtype_info ": caf=%08x taf=%" PRtype_info,
+ page_to_mfn(page), get_gpfn_from_mfn(page_to_mfn(page)),
+ type, page->count_info, page->u.inuse.type_info);
+ /* Noone else can get a reference. We hold the only ref. */
+ page->u.inuse.type_info = 0;
+ return 0;
+ }
+
+ /* Noone else is updating simultaneously. */
+ __set_bit(_PGT_validated, &page->u.inuse.type_info);
+ }
+
+ return 1;
+}
diff -r 405f0f847c0f -r c644eb4049ab xen/include/asm-ia64/mm.h
--- a/xen/include/asm-ia64/mm.h Thu Mar 9 23:24:31 2006
+++ b/xen/include/asm-ia64/mm.h Fri Mar 10 15:23:39 2006
@@ -41,32 +41,33 @@
/* Each frame can be threaded onto a doubly-linked list. */
struct list_head list;
+ /* Reference count and various PGC_xxx flags and fields. */
+ u32 count_info;
+
+ /* Context-dependent fields follow... */
+ union {
+
+ /* Page is in use: ((count_info & PGC_count_mask) != 0). */
+ struct {
+ /* Owner of this page (NULL if page is anonymous). */
+ u32 _domain; /* pickled format */
+ /* Type reference count and various PGT_xxx flags and fields. */
+ unsigned long type_info;
+ } __attribute__ ((packed)) inuse;
+
+ /* Page is on a free list: ((count_info & PGC_count_mask) == 0). */
+ struct {
+ /* Order-size of the free chunk this page is the head of. */
+ u32 order;
+ /* Mask of possibly-tainted TLBs. */
+ cpumask_t cpumask;
+ } __attribute__ ((packed)) free;
+
+ } u;
+
/* Timestamp from 'TLB clock', used to reduce need for safety flushes. */
u32 tlbflush_timestamp;
- /* Reference count and various PGC_xxx flags and fields. */
- u32 count_info;
-
- /* Context-dependent fields follow... */
- union {
-
- /* Page is in use by a domain. */
- struct {
- /* Owner of this page. */
- u32 _domain;
- /* Type reference count and various PGT_xxx flags and fields. */
- u32 type_info;
- } inuse;
-
- /* Page is on a free list. */
- struct {
- /* Mask of possibly-tainted TLBs. */
- cpumask_t cpumask;
- /* Order-size of the free chunk this page is the head of. */
- u8 order;
- } free;
-
- } u;
#if 0
// following added for Linux compiling
page_flags_t flags;
@@ -94,8 +95,15 @@
#define _PGT_pinned 27
#define PGT_pinned (1U<<_PGT_pinned)
-/* 27-bit count of uses of this frame as its current type. */
-#define PGT_count_mask ((1U<<27)-1)
+/* The 11 most significant bits of virt address if this is a page table. */
+#define PGT_va_shift 16
+#define PGT_va_mask (((1U<<11)-1)<<PGT_va_shift)
+/* Is the back pointer still mutable (i.e. not fixed yet)? */
+#define PGT_va_mutable (((1U<<11)-1)<<PGT_va_shift)
+/* Is the back pointer unknown (e.g., p.t. is mapped at multiple VAs)? */
+#define PGT_va_unknown (((1U<<11)-2)<<PGT_va_shift)
+/* 16-bit count of uses of this frame as its current type. */
+#define PGT_count_mask ((1U<<16)-1)
/* Cleared when the owning guest 'frees' this page. */
#define _PGC_allocated 31
@@ -138,7 +146,6 @@
static inline void put_page(struct page_info *page)
{
-#ifdef VALIDATE_VT // doesn't work with non-VTI in grant tables yet
u32 nx, x, y = page->count_info;
do {
@@ -149,14 +156,12 @@
if (unlikely((nx & PGC_count_mask) == 0))
free_domheap_page(page);
-#endif
}
/* count_info and ownership are checked atomically. */
static inline int get_page(struct page_info *page,
struct domain *domain)
{
-#ifdef VALIDATE_VT
u64 x, nx, y = *((u64*)&page->count_info);
u32 _domain = pickle_domptr(domain);
@@ -172,14 +177,13 @@
return 0;
}
}
- while(unlikely(y = cmpxchg(&page->count_info, x, nx)) != x);
-#endif
+ while(unlikely((y = cmpxchg((u64*)&page->count_info, x, nx)) != x));
return 1;
}
-/* No type info now */
-#define put_page_type(page)
-#define get_page_type(page, type) 1
+extern void put_page_type(struct page_info *page);
+extern int get_page_type(struct page_info *page, u32 type);
+
static inline void put_page_and_type(struct page_info *page)
{
put_page_type(page);
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