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authorDavid Vrabel <david.vrabel@citrix.com>2014-07-11 16:42:34 +0100
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2014-07-14 15:28:02 -0400
commit162e371712768248a38646eefa71af38b6e0f8ce (patch)
tree899b44d49c7b6cce18e831bb32deb4496d0e016e /arch/arm/xen
parenta2c5ae65addb122270cf4115c92039c5b8bf15b9 (diff)
downloadlinux-162e371712768248a38646eefa71af38b6e0f8ce.tar.bz2
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 'arch/arm/xen')
-rw-r--r--arch/arm/xen/grant-table.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm/xen/grant-table.c b/arch/arm/xen/grant-table.c
index 859a9bb002d5..91cf08ba1e95 100644
--- a/arch/arm/xen/grant-table.c
+++ b/arch/arm/xen/grant-table.c
@@ -51,3 +51,8 @@ int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
{
return -ENOSYS;
}
+
+int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
+{
+ return 0;
+}