• David Vrabel's avatar
    x86/xen: safely map and unmap grant frames when in atomic context · b7dd0e35
    David Vrabel authored
    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 (which ensures
    that the required page tables are pre-allocated).
    Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
    Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    b7dd0e35
grant_table.h 7.25 KB