Ensure offlined buddy head pages are annotated as order-0 pages.
When a buddy containing pages marked for offlining is processed,
reserve_offlined_page() rebuilds any surviving healthy buddies
and moves the offlined subpages onto the offlined lists.
If the buddy head itself is offlined it was previously left
annotated with the original buddy order even though it has
been split into a single page.
This has no functional impact as the order of an offlined
page is not used for any decision making and onlining, but
it is misleading when inspecting the page's metadata.
Set PFN_ORDER(cur_head) to 0 for all pages moved to the
lists of offlined and broken pages so the page's stored
order reflects its actual size.
Signed-off-by: Bernhard Kaindl <bernhard.kaindl@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Anthony reported a boot-time assertion in init_xen_time() via efi_get_time()
-> efi_rs_enter() in vcpu_save_fpu() on a Broadwell-D system:
Assertion '!is_idle_vcpu(v)' failed at arch/x86/i387.c:195
This became fragile after the lazy-FPU removal cleanup series:
In 1792bb9a99 ("x86: Cleanup cr0.TS flag handling"),
efi_rs_enter() was changed from save_fpu_enable() to vcpu_save_fpu(curr),
which unconditionally asserts !is_idle_vcpu(v)
so an EFI runtime call in idle context now asserts.
Likewise, in dba44e0512 ("x86: Remove fully_eager_fpu"),
efi_rs_leave() was changed to call vcpu_restore_fpu(curr),
which has the same assertion and can fail for the same reason.
Guard both EFI runtime FPU calls with !is_idle_vcpu() to skip save/restore
for idle vCPUs, which don't have an FPU context to save/restore,
much like the calls are guarded in __context_switch(),
where save/restore is done only for non-idle vCPUs.
Fixes: 1792bb9a99 ("x86: Cleanup cr0.TS flag handling")
Fixes: dba44e0512 ("x86: Remove fully_eager_fpu")
Reported-by: Anthony PERARD <anthony.perard@vates.tech>
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Bernhard Kaindl <bernhard.kaindl@citrix.com>
Tested-by: Anthony PERARD <anthony.perard@vates.tech>
Acked-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
reserve_offlined_page() reserves pages marked for offlining and
returns free buddies from the remaining healthy tail pages back
to the free list.
Consider an order-2 buddy (4 pages) with the following layout:
+---------------+---------------+---------------+---------------+
| head page tail page 1, tail page 2 tail page 3 |
| PFN_ORDER(pg) marked as to |
| == 2 be offlined |
+---------------+---------------+---------------+---------------+
The expected result after removing tail page 1 and returning the
remaining healthy pages to the free list would be:
+---------------+ +---------------+---------------+
| single page | offlined page | head page tail page |
| PFN_ORDER(pg) | not returned | PFN_ORDER(pg) |
| == 0 | to the heap | == 1 |
+---------------+ +---------------+---------------+
A trivial off-by-one error in the growth loop stops the growth loop
early before the tail end of the original buddy and we end up with:
+---------------+ +---------------+---------------+
| single page | offlined page | single page | single page |
| PFN_ORDER(pg) | not returned | PFN_ORDER(pg) | PFN_ORDER(pg) |
| == 0 | to the heap | == 0 | == 0 |
+---------------+ +---------------+---------------+
If the offlined page was in a much larger buddy, this would lead
to much more memory not available for higher order allocations
requiring the full tail end of the original buddy for allocation.
Fix the growth loop to correctly grow the buddy to the tail end
to make the full allocation unit available for future allocation.
Fixes: e4865c2315 ('Page offline support in Xen side')
Signed-off-by: Bernhard Kaindl <bernhard.kaindl@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
reserve_offlined_page() fails to verify alignment when growing
buddies around offlined pages. Consequently, misaligned buddies
may be constructed from non-offlined page ranges and returned to
the free lists.
After a particular sequence of allocations and frees, pages
from such a misaligned buddy may be allocated more than once,
eventually triggering a Xen BUG() in alloc_heap_pages().
Fixes: e4865c2315 ('Page offline support in Xen side')
Signed-off-by: Bernhard Kaindl <bernhard.kaindl@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
The current use of long for total_avail_pages and outstanding_claims
creates an unnecessary mix of signed and unsigned types during page
allocation calculations. This necessitates awkward constructs
like '+ 0UL' to satisfy type matching in macros such as min().
Address this by normalizing `total_avail_pages` and `outstanding_claims`
from `long` to `unsigned long`.
As a direct consequence of making `total_avail_pages` unsigned, the
post-decrement assertions checking for `>= 0` are no longer logically
sound. Adjust those assertions to pre-decrement checks.
No functional change intended.
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Bernhard Kaindl <bernhard.kaindl@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Fixes for Py3:
* class Delayed(): file not defined; also an error for pylint -E. Inherit
object instead for Py2 compatibility. Fix DomainInfo() too.
* Inconsistent use of tabs and spaces for indentation (in one block)
Signed-off-by: Bernhard Kaindl <bernhard.kaindl@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Bernhard Kaindl