From bce93fa13f7ff778820e3ef511c4a117075cdd3b Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Wed, 7 Aug 2013 16:52:34 +0200 Subject: [PATCH] x86: don't use destroy_xen_mappings() for vunmap() Its attempt to tear down intermediate page table levels may race with map_pages_to_xen() establishing them, and now that map_domain_page_global() is backed by vmap() this teardown is also wasteful (as it's very likely to need the same address space populated again within foreseeable time). Signed-off-by: Jan Beulich Acked-by: Keir Fraser master commit: 68caac7f6f4687241a24e804a9fca19aa26fe183 master date: 2013-07-17 10:21:33 +0200 --- xen/common/vmap.c | 4 ++++ xen/include/asm-x86/page.h | 1 + 2 files changed, 5 insertions(+) diff --git a/xen/common/vmap.c b/xen/common/vmap.c index c2d8a8ce70..5f92be4f20 100644 --- a/xen/common/vmap.c +++ b/xen/common/vmap.c @@ -196,9 +196,13 @@ void *vmap(const unsigned long *mfn, unsigned int nr) void vunmap(const void *va) { +#ifndef _PAGE_NONE unsigned long addr = (unsigned long)va; destroy_xen_mappings(addr, addr + PAGE_SIZE * vm_size(va)); +#else /* Avoid tearing down intermediate page tables. */ + map_pages_to_xen((unsigned long)va, 0, vm_size(va), _PAGE_NONE); +#endif vm_free(va); } #endif diff --git a/xen/include/asm-x86/page.h b/xen/include/asm-x86/page.h index 998a0c79dd..2c3cc2dddf 100644 --- a/xen/include/asm-x86/page.h +++ b/xen/include/asm-x86/page.h @@ -288,6 +288,7 @@ extern l1_pgentry_t l1_identmap[L1_PAGETABLE_ENTRIES], void paging_init(void); #endif /* !defined(__ASSEMBLY__) */ +#define _PAGE_NONE _AC(0x000,U) #define _PAGE_PRESENT _AC(0x001,U) #define _PAGE_RW _AC(0x002,U) #define _PAGE_USER _AC(0x004,U) -- 2.39.5