From 162e371712768248a38646eefa71af38b6e0f8ce Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Fri, 11 Jul 2014 16:42:34 +0100 Subject: 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 Signed-off-by: Konrad Rzeszutek Wilk ---- [v2: Add comment about alloc_vm_area] [v3: Fix compile error found by 0-day bot] --- arch/arm/xen/grant-table.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/arm') diff --git a/arch/arm/xen/grant-table.c b/arch/arm/xen/grant-table.c index 859a9bb..91cf08b 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; +} -- cgit v1.1