diff options
| author | David Vrabel <david.vrabel@citrix.com> | 2014-07-11 16:42:34 +0100 |
|---|---|---|
| committer | David Vrabel <david.vrabel@citrix.com> | 2014-07-30 14:22:47 +0100 |
| commit | b7dd0e350e0bd4c0fddcc9b8958342700b00b168 (patch) | |
| tree | f69ea88b9e9f5e234d5c5d2f3f0ceaa22d3049b8 /drivers/xen | |
| parent | fb9a0c443691ceaab3daba966bbbd9f5ff3aa26f (diff) | |
| download | lwn-b7dd0e350e0bd4c0fddcc9b8958342700b00b168.tar.gz lwn-b7dd0e350e0bd4c0fddcc9b8958342700b00b168.zip | |
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 (which ensures
that the required page tables are pre-allocated).
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/xen')
| -rw-r--r-- | drivers/xen/grant-table.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index 5d4de88fe5b8..eeba7544f0cd 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -1195,18 +1195,20 @@ static int gnttab_expand(unsigned int req_entries) int gnttab_init(void) { int i; + unsigned long max_nr_grant_frames; unsigned int max_nr_glist_frames, nr_glist_frames; unsigned int nr_init_grefs; int ret; gnttab_request_version(); + max_nr_grant_frames = gnttab_max_grant_frames(); nr_grant_frames = 1; /* Determine the maximum number of frames required for the * grant reference free list on the current hypervisor. */ BUG_ON(grefs_per_grant_frame == 0); - max_nr_glist_frames = (gnttab_max_grant_frames() * + max_nr_glist_frames = (max_nr_grant_frames * grefs_per_grant_frame / RPP); gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *), @@ -1223,6 +1225,11 @@ int gnttab_init(void) } } + ret = arch_gnttab_init(max_nr_grant_frames, + nr_status_frames(max_nr_grant_frames)); + if (ret < 0) + goto ini_nomem; + if (gnttab_setup() < 0) { ret = -ENODEV; goto ini_nomem; |