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authorStefano Stabellini <stefano.stabellini@eu.citrix.com>2013-07-23 17:23:54 +0000
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2013-08-20 10:25:35 -0400
commitee0726407feaf504dff304fb603652fb2d778b42 (patch)
tree408473642b805ba2e56b94766f877fcb8518f24b /arch/x86/xen/p2m.c
parent072b2064b88f709c53a83c6ec1f1cb17bf7c0abf (diff)
downloadlinux-ee0726407feaf504dff304fb603652fb2d778b42.tar.bz2
xen/m2p: use GNTTABOP_unmap_and_replace to reinstate the original mapping
GNTTABOP_unmap_grant_ref unmaps a grant and replaces it with a 0 mapping instead of reinstating the original mapping. Doing so separately would be racy. To unmap a grant and reinstate the original mapping atomically we use GNTTABOP_unmap_and_replace. GNTTABOP_unmap_and_replace doesn't work with GNTMAP_contains_pte, so don't use it for kmaps. GNTTABOP_unmap_and_replace zeroes the mapping passed in new_addr so we have to reinstate it, however that is a per-cpu mapping only used for balloon scratch pages, so we can be sure that it's not going to be accessed while the mapping is not valid. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Reviewed-by: David Vrabel <david.vrabel@citrix.com> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> CC: alex@alex.org.uk CC: dcrisan@flexiant.com [v1: Konrad fixed up the conflicts] Conflicts: arch/x86/xen/p2m.c
Diffstat (limited to 'arch/x86/xen/p2m.c')
-rw-r--r--arch/x86/xen/p2m.c21
1 files changed, 15 insertions, 6 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 74672eeac881..0d4ec35895d4 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -161,6 +161,7 @@
#include <asm/xen/page.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
+#include <xen/balloon.h>
#include <xen/grant_table.h>
#include "multicalls.h"
@@ -967,7 +968,10 @@ int m2p_remove_override(struct page *page,
if (kmap_op != NULL) {
if (!PageHighMem(page)) {
struct multicall_space mcs;
- struct gnttab_unmap_grant_ref *unmap_op;
+ struct gnttab_unmap_and_replace *unmap_op;
+ struct page *scratch_page = get_balloon_scratch_page();
+ unsigned long scratch_page_address = (unsigned long)
+ __va(page_to_pfn(scratch_page) << PAGE_SHIFT);
/*
* It might be that we queued all the m2p grant table
@@ -990,20 +994,25 @@ int m2p_remove_override(struct page *page,
}
mcs = xen_mc_entry(
- sizeof(struct gnttab_unmap_grant_ref));
+ sizeof(struct gnttab_unmap_and_replace));
unmap_op = mcs.args;
unmap_op->host_addr = kmap_op->host_addr;
+ unmap_op->new_addr = scratch_page_address;
unmap_op->handle = kmap_op->handle;
- unmap_op->dev_bus_addr = 0;
MULTI_grant_table_op(mcs.mc,
- GNTTABOP_unmap_grant_ref, unmap_op, 1);
+ GNTTABOP_unmap_and_replace, unmap_op, 1);
xen_mc_issue(PARAVIRT_LAZY_MMU);
- set_pte_at(&init_mm, address, ptep,
- pfn_pte(pfn, PAGE_KERNEL));
+ mcs = __xen_mc_entry(0);
+ MULTI_update_va_mapping(mcs.mc, scratch_page_address,
+ pfn_pte(page_to_pfn(get_balloon_scratch_page()),
+ PAGE_KERNEL_RO), 0);
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
kmap_op->host_addr = 0;
+ put_balloon_scratch_page();
}
}