Jan Beulich
2009-May-20 13:33 UTC
[Xen-devel] [PATCH] x86-64: also handle virtual aliases of Xen imiage pages
With the unification of the heaps, the pages freed from the Xen boot
image now can also end up being allocated to a domain, and hence the
respective aliases need handling when such pages get their cacheability
attributes changed.
Rather than establishing multiple mappings with non-WB attributes
(which temporarily still can cause aliasing issues), simply unmap those
pages from the Xen virtual space, and re-map them (to allow re-
establishing of eventual large page mappings) when the cachability
attribute for them gets restored to normal (WB).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
--- 2009-05-19.orig/xen/arch/x86/mm.c 2009-05-20 12:56:01.000000000 +0200
+++ 2009-05-19/xen/arch/x86/mm.c 2009-05-20 14:10:20.000000000 +0200
@@ -709,6 +709,23 @@ int is_iomem_page(unsigned long mfn)
return (page_get_owner(page) == dom_io);
}
+static void update_xen_mappings(unsigned long mfn, unsigned long cacheattr)
+{
+#ifdef __x86_64__
+ bool_t alias = mfn >= PFN_DOWN(xen_phys_start) &&
+ mfn < PFN_UP(xen_phys_start + (unsigned long)_end -
XEN_VIRT_START);
+ unsigned long xen_va + XEN_VIRT_START + ((mfn -
PFN_DOWN(xen_phys_start)) << PAGE_SHIFT);
+
+ if ( unlikely(alias) && cacheattr )
+ map_pages_to_xen(xen_va, mfn, 1, 0);
+ map_pages_to_xen((unsigned long)mfn_to_virt(mfn), mfn, 1,
+ PAGE_HYPERVISOR | cacheattr_to_pte_flags(cacheattr));
+ if ( unlikely(alias) && !cacheattr )
+ map_pages_to_xen(xen_va, mfn, 1, PAGE_HYPERVISOR);
+#endif
+}
+
int
get_page_from_l1e(
@@ -796,10 +813,7 @@ get_page_from_l1e(
y = cmpxchg(&page->count_info, x, nx);
}
-#ifdef __x86_64__
- map_pages_to_xen((unsigned long)mfn_to_virt(mfn), mfn, 1,
- PAGE_HYPERVISOR | cacheattr_to_pte_flags(cacheattr));
-#endif
+ update_xen_mappings(mfn, cacheattr);
}
return 1;
@@ -857,12 +871,6 @@ get_page_from_l2e(
return -EINVAL;
}
} while ( m++ < (mfn + (L1_PAGETABLE_ENTRIES-1)) );
-
-#ifdef __x86_64__
- map_pages_to_xen(
- (unsigned long)mfn_to_virt(mfn), mfn, L1_PAGETABLE_ENTRIES,
- PAGE_HYPERVISOR | l2e_get_flags(l2e));
-#endif
}
return rc;
@@ -2405,10 +2413,7 @@ void cleanup_page_cacheattr(struct page_
BUG_ON(is_xen_heap_page(page));
-#ifdef __x86_64__
- map_pages_to_xen((unsigned long)page_to_virt(page), page_to_mfn(page),
- 1, PAGE_HYPERVISOR);
-#endif
+ update_xen_mappings(page_to_mfn(page), 0);
}
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