42 lines
1.3 KiB
Diff
42 lines
1.3 KiB
Diff
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# Commit 68caac7f6f4687241a24e804a9fca19aa26fe183
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# Date 2013-07-17 10:21:33 +0200
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# Author Jan Beulich <jbeulich@suse.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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x86: don't use destroy_xen_mappings() for vunmap()
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Its attempt to tear down intermediate page table levels may race with
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map_pages_to_xen() establishing them, and now that
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map_domain_page_global() is backed by vmap() this teardown is also
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wasteful (as it's very likely to need the same address space populated
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again within foreseeable time).
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Acked-by: Keir Fraser <keir@xen.org>
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--- a/xen/common/vmap.c
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+++ b/xen/common/vmap.c
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@@ -196,9 +196,13 @@ void *vmap(const unsigned long *mfn, uns
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void vunmap(const void *va)
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{
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+#ifndef _PAGE_NONE
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unsigned long addr = (unsigned long)va;
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destroy_xen_mappings(addr, addr + PAGE_SIZE * vm_size(va));
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+#else /* Avoid tearing down intermediate page tables. */
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+ map_pages_to_xen((unsigned long)va, 0, vm_size(va), _PAGE_NONE);
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+#endif
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vm_free(va);
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}
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#endif
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--- a/xen/include/asm-x86/page.h
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+++ b/xen/include/asm-x86/page.h
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@@ -288,6 +288,7 @@ extern l1_pgentry_t l1_identmap[L1_PAGET
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void paging_init(void);
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#endif /* !defined(__ASSEMBLY__) */
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+#define _PAGE_NONE _AC(0x000,U)
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#define _PAGE_PRESENT _AC(0x001,U)
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#define _PAGE_RW _AC(0x002,U)
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#define _PAGE_USER _AC(0x004,U)
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