xen-devel
Re: [Xen-devel] [RESEND] Question about recursive mappings
Keir Fraser wrote:
On 24 May 2006, at 21:12, Mathieu Ropert wrote:
Ok, i've done a little patch which seems to resolve the issue on my
test setup. Basically, i've modified get_linear_pagetable(), added a
level parameter and call it for each level but level 1.
I need to do a little more test before i post the patch. As tomorrow
is a national day, it should be ready friday.
Can you try creating some mutually recursive pagetables (i.e., one
linearly maps the other, and vice versa) and then try 'xm destroy'ing
the domain?
-- Keir
Here's the patch that solves my issue. I've only tested it for x86_64,
so any feedback on x86/PAE would be appreciated.
Tried to make mutually recursive tables and destroy the domain as you
suggested, no problem encountered.
Note that the union i used may seem a bit overkill, but i didn't saw any
other way to make it generic (even if brutal casting should work on any
x86/x86_64 arch).
Applies to cset 10166.
Mathieu
Signed-off-by: Mathieu Ropert <mro@xxxxxxxxxx>
diff -u -r a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c 2006年05月26日 11:05:08.000000000 +0200
+++ b/xen/arch/x86/mm.c 2006年05月26日 11:14:33.000000000 +0200
@@ -415,7 +415,7 @@
*/
static int
get_linear_pagetable(
- root_pgentry_t re, unsigned long re_pfn, struct domain *d)
+ pgentry_t re, unsigned long re_pfn, struct domain *d, int level)
{
unsigned long x, y;
struct page_info *page;
@@ -423,13 +423,13 @@
ASSERT( !shadow_mode_refcounts(d) );
- if ( (root_get_flags(re) & _PAGE_RW) )
+ if ( (pgentry_get_flags(re, level) & _PAGE_RW) )
{
MEM_LOG("Attempt to create linear p.t. with write perms");
return 0;
}
- if ( (pfn = root_get_pfn(re)) != re_pfn )
+ if ( (pfn = pgentry_get_pfn(re, level)) != re_pfn )
{
/* Make sure the mapped frame belongs to the correct domain. */
if ( unlikely(!get_page_from_pagenr(pfn, d)) )
@@ -444,8 +444,7 @@
do {
x = y;
if ( unlikely((x & PGT_count_mask) == PGT_count_mask) ||
- unlikely((x & (PGT_type_mask|PGT_validated)) !=
- (PGT_root_page_table|PGT_validated)) )
+ unlikely(!(x & PGT_validated) || !is_ptp(x)))
{
put_page(page);
return 0;
@@ -532,9 +531,12 @@
vaddr <<= PGT_va_shift;
rc = get_page_and_type_from_pagenr(
l2e_get_pfn(l2e), PGT_l1_page_table | vaddr, d);
-#if CONFIG_PAGING_LEVELS == 2
- if ( unlikely(!rc) )
- rc = get_linear_pagetable(l2e, pfn, d);
+#if CONFIG_PAGING_LEVELS >= 2
+ if ( unlikely(!rc) ) {
+ pgentry_t re;
+ re.l2.l2 = l2e.l2;
+ rc = get_linear_pagetable(re, pfn, d, 2);
+ }
#endif
return rc;
}
@@ -564,9 +566,12 @@
rc = get_page_and_type_from_pagenr(
l3e_get_pfn(l3e),
PGT_l2_page_table | vaddr, d);
-#if CONFIG_PAGING_LEVELS == 3
- if ( unlikely(!rc) )
- rc = get_linear_pagetable(l3e, pfn, d);
+#if CONFIG_PAGING_LEVELS >= 3
+ if ( unlikely(!rc) ) {
+ pgentry_t re;
+ re.l3.l3 = l3e.l3;
+ rc = get_linear_pagetable(re, pfn, d, 3);
+ }
#endif
return rc;
}
@@ -597,8 +602,11 @@
l4e_get_pfn(l4e),
PGT_l3_page_table | vaddr, d);
- if ( unlikely(!rc) )
- rc = get_linear_pagetable(l4e, pfn, d);
+ if ( unlikely(!rc) ) {
+ pgentry_t re;
+ re.l4.l4 = l4e.l4;
+ rc = get_linear_pagetable(re, pfn, d, 4);
+ }
return rc;
}
diff -u -r a/xen/include/asm-x86/page.h b/xen/include/asm-x86/page.h
--- a/xen/include/asm-x86/page.h 2006年05月26日 11:05:09.000000000 +0200
+++ b/xen/include/asm-x86/page.h 2006年05月24日 12:49:42.000000000 +0200
@@ -176,6 +176,67 @@
#define pagetable_get_pfn(x) ((x).pfn)
#define mk_pagetable(pa) \
({ pagetable_t __p; __p.pfn = (pa) >> PAGE_SHIFT; __p; })
+
+typedef union {
+ l1_pgentry_t l1;
+#if CONFIG_PAGING_LEVELS >= 2
+ l2_pgentry_t l2;
+#if CONFIG_PAGING_LEVELS >= 3
+ l3_pgentry_t l3;
+#if CONFIG_PAGING_LEVELS == 4
+ l4_pgentry_t l4;
+#endif /* LEVELS == 4 */
+#endif /* LEVELS >= 3 */
+#endif /* LEVELS >= 2 */
+} pgentry_t;
+
+static inline intpte_t pgentry_get_flags(pgentry_t p, int level)
+{
+ switch (level)
+ {
+ case 1:
+ return l1e_get_flags(p.l1);
+#if CONFIG_PAGING_LEVELS >= 2
+ case 2:
+ return l2e_get_flags(p.l2);
+#if CONFIG_PAGING_LEVELS >= 3
+ case 3:
+ return l3e_get_flags(p.l3);
+#if CONFIG_PAGING_LEVELS == 4
+ case 4:
+ return l4e_get_flags(p.l4);
+#endif /* LEVELS == 4 */
+#endif /* LEVELS >= 3 */
+#endif /* LEVELS >= 2 */
+ default:
+ /* should not happen */
+ return 0;
+ }
+}
+
+static inline intpte_t pgentry_get_pfn(pgentry_t p, int level)
+{
+ switch (level)
+ {
+ case 1:
+ return l1e_get_pfn(p.l1);
+#if CONFIG_PAGING_LEVELS >= 2
+ case 2:
+ return l2e_get_pfn(p.l2);
+#if CONFIG_PAGING_LEVELS >= 3
+ case 3:
+ return l3e_get_pfn(p.l3);
+#if CONFIG_PAGING_LEVELS == 4
+ case 4:
+ return l4e_get_pfn(p.l4);
+#endif /* LEVELS == 4 */
+#endif /* LEVELS >= 3 */
+#endif /* LEVELS >= 2 */
+ default:
+ /* should not happen */
+ return 0;
+ }
+}
#endif
#define clear_page(_p) memset((void *)(_p), 0, PAGE_SIZE)
diff -u -r a/xen/include/asm-x86/x86_32/page-2level.h
b/xen/include/asm-x86/x86_32/page-2level.h
--- a/xen/include/asm-x86/x86_32/page-2level.h 2006年05月26日 11:05:09.000000000
+0200
+++ b/xen/include/asm-x86/x86_32/page-2level.h 2006年05月26日 11:09:56.000000000
+0200
@@ -28,6 +28,11 @@
#endif /* !__ASSEMBLY__ */
+/* Check if page type is page table (any level) */
+#define is_ptp(x) \
+ ((x & PGT_type_mask) == PGT_l1_page_table \
+ || (x & PGT_type_mask) == PGT_l2_page_table)
+
/* root table */
#define root_get_pfn l2e_get_pfn
#define root_get_flags l2e_get_flags
diff -u -r a/xen/include/asm-x86/x86_32/page-3level.h
b/xen/include/asm-x86/x86_32/page-3level.h
--- a/xen/include/asm-x86/x86_32/page-3level.h 2006年05月26日 11:05:09.000000000
+0200
+++ b/xen/include/asm-x86/x86_32/page-3level.h 2006年05月26日 11:10:47.000000000
+0200
@@ -38,6 +38,12 @@
#endif /* !__ASSEMBLY__ */
+/* Check if page type is page table (any level) */
+#define is_ptp(x) \
+ ((x & PGT_type_mask) == PGT_l1_page_table \
+ || (x & PGT_type_mask) == PGT_l2_page_table \
+ || (x & PGT_type_mask) == PGT_l3_page_table)
+
/* root table */
#define root_get_pfn l3e_get_pfn
#define root_get_flags l3e_get_flags
diff -u -r a/xen/include/asm-x86/x86_64/page.h
b/xen/include/asm-x86/x86_64/page.h
--- a/xen/include/asm-x86/x86_64/page.h 2006年05月26日 11:05:09.000000000 +0200
+++ b/xen/include/asm-x86/x86_64/page.h 2006年05月26日 11:07:46.000000000 +0200
@@ -41,6 +41,13 @@
#endif /* !__ASSEMBLY__ */
+/* Check if page type is page table (any level) */
+#define is_ptp(x) \
+ ((x & PGT_type_mask) == PGT_l1_page_table \
+ || (x & PGT_type_mask) == PGT_l2_page_table \
+ || (x & PGT_type_mask) == PGT_l3_page_table \
+ || (x & PGT_type_mask) == PGT_l4_page_table)
+
/* Given a virtual address, get an entry offset into a linear page table. */
#define l1_linear_offset(_a) (((_a) & VADDR_MASK) >> L1_PAGETABLE_SHIFT)
#define l2_linear_offset(_a) (((_a) & VADDR_MASK) >> L2_PAGETABLE_SHIFT)
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