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authorDavid Vrabel <david.vrabel@citrix.com>2014-07-11 19:42:34 +0400
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2014-07-14 23:28:02 +0400
commit162e371712768248a38646eefa71af38b6e0f8ce (patch)
tree899b44d49c7b6cce18e831bb32deb4496d0e016e /include/xen
parenta2c5ae65addb122270cf4115c92039c5b8bf15b9 (diff)
downloadlinux-162e371712768248a38646eefa71af38b6e0f8ce.tar.xz
x86/xen: safely map and unmap grant frames when in atomic context
arch_gnttab_map_frames() and arch_gnttab_unmap_frames() are called in atomic context but were calling alloc_vm_area() which might sleep. Also, if a driver attempts to allocate a grant ref from an interrupt and the table needs expanding, then the CPU may already by in lazy MMU mode and apply_to_page_range() will BUG when it tries to re-enable lazy MMU mode. These two functions are only used in PV guests. Introduce arch_gnttab_init() to allocates the virtual address space in advance. Avoid the use of apply_to_page_range() by using saving and using the array of PTE addresses from the alloc_vm_area() call. N.B. 'alloc_vm_area' pre-allocates the pagetable so there is no need to worry about having to do a PGD/PUD/PMD walk (like apply_to_page_range does) and we can instead do set_pte. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> ---- [v2: Add comment about alloc_vm_area] [v3: Fix compile error found by 0-day bot]
Diffstat (limited to 'include/xen')
-rw-r--r--include/xen/grant_table.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index a5af2a26d94f..5c1aba154b64 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -170,6 +170,7 @@ gnttab_set_unmap_op(struct gnttab_unmap_grant_ref *unmap, phys_addr_t addr,
unmap->dev_bus_addr = 0;
}
+int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status);
int arch_gnttab_map_shared(xen_pfn_t *frames, unsigned long nr_gframes,
unsigned long max_nr_gframes,
void **__shared);