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xen/p2m: Don't call get_balloon_scratch_page() twice, keep interrupts disabled for multicalls 

m2p_remove_override() calls get_balloon_scratch_page() in
MULTI_update_va_mapping() even though it already has pointer to this page from
the earlier call (in scratch_page). This second call doesn't have a matching
put_balloon_scratch_page() thus not restoring preempt count back. (Also, there
is no put_balloon_scratch_page() in the error path.)

In addition, the second multicall uses __xen_mc_entry() which does not disable
interrupts. Rearrange xen_mc_* calls to keep interrupts off while performing
multicalls.

This commit fixes a regression introduced by:

commit ee0726407f
Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Date:   Tue Jul 23 17:23:54 2013 +0000

    xen/m2p: use GNTTABOP_unmap_and_replace to reinstate the original mapping

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
This commit is contained in:
Boris Ostrovsky 2013-09-09 10:44:26 +00:00 committed by Stefano Stabellini
parent 9dd4b2944c
commit d7f8f48d1e
1 changed files with 6 additions and 4 deletions
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10
arch/x86/xen/p2m.c
View File

@ -990,10 +990,13 @@ int m2p_remove_override(struct page *page,
printk(KERN_WARNING "m2p_remove_override: " printk(KERN_WARNING "m2p_remove_override: "
"pfn %lx mfn %lx, failed to modify kernel mappings", "pfn %lx mfn %lx, failed to modify kernel mappings",
pfn, mfn); pfn, mfn);
put_balloon_scratch_page();
return -1; return -1;
} }
mcs = xen_mc_entry( xen_mc_batch();
mcs = __xen_mc_entry(
sizeof(struct gnttab_unmap_and_replace)); sizeof(struct gnttab_unmap_and_replace));
unmap_op = mcs.args; unmap_op = mcs.args;
unmap_op->host_addr = kmap_op->host_addr; unmap_op->host_addr = kmap_op->host_addr;
@ -1003,12 +1006,11 @@ int m2p_remove_override(struct page *page,
MULTI_grant_table_op(mcs.mc, MULTI_grant_table_op(mcs.mc,
GNTTABOP_unmap_and_replace, unmap_op, 1); GNTTABOP_unmap_and_replace, unmap_op, 1);
xen_mc_issue(PARAVIRT_LAZY_MMU);
mcs = __xen_mc_entry(0); mcs = __xen_mc_entry(0);
MULTI_update_va_mapping(mcs.mc, scratch_page_address, MULTI_update_va_mapping(mcs.mc, scratch_page_address,
pfn_pte(page_to_pfn(get_balloon_scratch_page()), pfn_pte(page_to_pfn(scratch_page),
PAGE_KERNEL_RO), 0); PAGE_KERNEL_RO), 0);
xen_mc_issue(PARAVIRT_LAZY_MMU); xen_mc_issue(PARAVIRT_LAZY_MMU);
kmap_op->host_addr = 0; kmap_op->host_addr = 0;