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| author | David Vrabel <david.vrabel@citrix.com> | 2013-09-11 17:45:44 +0000 |
|---|---|---|
| committer | Stefano Stabellini <stefano.stabellini@eu.citrix.com> | 2013-09-11 17:52:58 +0000 |
| commit | 2bad07ce28a0f61c1e776f99aa05f85e4e689e24 (patch) | |
| tree | b13abf74f1f22eaf3d71e5c399c599f72fd77c82 /drivers/xen | |
| parent | c3b7cb1fd8c1513be99fb3cfb7f39c5116d80dac (diff) | |
| download | linux-2bad07ce28a0f61c1e776f99aa05f85e4e689e24.tar.gz linux-2bad07ce28a0f61c1e776f99aa05f85e4e689e24.tar.bz2 linux-2bad07ce28a0f61c1e776f99aa05f85e4e689e24.zip | |
xen/balloon: ensure preemption is disabled when using a scratch page
In decrease_reservation(), if the kernel is preempted between updating
the mapping and updating the p2m then they may end up using different
scratch pages.
Use get_balloon_scratch_page() and put_balloon_scratch_page() which use
get_cpu_var() and put_cpu_var() to correctly disable preemption.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
Diffstat (limited to 'drivers/xen')
| -rw-r--r-- | drivers/xen/balloon.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 3101cf6daf56..4a43bc31ed3c 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -380,6 +380,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) enum bp_state state = BP_DONE; unsigned long pfn, i; struct page *page; + struct page *scratch_page; int ret; struct xen_memory_reservation reservation = { .address_bits = 0, @@ -399,6 +400,8 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) if (nr_pages > ARRAY_SIZE(frame_list)) nr_pages = ARRAY_SIZE(frame_list); + scratch_page = get_balloon_scratch_page(); + for (i = 0; i < nr_pages; i++) { page = alloc_page(gfp); if (page == NULL) { @@ -416,7 +419,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) if (xen_pv_domain() && !PageHighMem(page)) { ret = HYPERVISOR_update_va_mapping( (unsigned long)__va(pfn << PAGE_SHIFT), - pfn_pte(page_to_pfn(__get_cpu_var(balloon_scratch_page)), + pfn_pte(page_to_pfn(scratch_page), PAGE_KERNEL_RO), 0); BUG_ON(ret); } @@ -432,14 +435,14 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) pfn = mfn_to_pfn(frame_list[i]); if (!xen_feature(XENFEAT_auto_translated_physmap)) { unsigned long p; - struct page *pg; - pg = __get_cpu_var(balloon_scratch_page); - p = page_to_pfn(pg); + p = page_to_pfn(scratch_page); __set_phys_to_machine(pfn, pfn_to_mfn(p)); } balloon_append(pfn_to_page(pfn)); } + put_balloon_scratch_page(); + set_xen_guest_handle(reservation.extent_start, frame_list); reservation.nr_extents = nr_pages; ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); |