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author | David Vrabel <david.vrabel@citrix.com> | 2014-07-11 17:42:34 +0200 |
---|---|---|
committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2014-07-14 21:28:02 +0200 |
commit | 162e371712768248a38646eefa71af38b6e0f8ce (patch) | |
tree | 899b44d49c7b6cce18e831bb32deb4496d0e016e /drivers/xen/grant-table.c | |
parent | MAINTAINERS: Make me the Xen block subsystem (front and back) maintainer (diff) | |
download | linux-162e371712768248a38646eefa71af38b6e0f8ce.tar.xz linux-162e371712768248a38646eefa71af38b6e0f8ce.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.
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 'drivers/xen/grant-table.c')
-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; |